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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Suggested Citation:"Tropospheric Ozone." National Academy of Engineering. 1993. Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation. Washington, DC: The National Academies Press. doi: 10.17226/2127.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Keeping Pace with Science and Engineering. 1993. Pp. 39-90. Washington, DC: National Academy Press. Tropospheric Ozone Philip M. Roth, Stephen D. Ziman, and James D. Fine The National Research Council (NRC) Committee on Tropospheric Ozone Formation and Measurement prefaced its recent report, Rethinking the Ozone Problem in Urban and Regional Air Pollution, by declaring that "ambient ozone . . . represents one of this country's most pervasive and stubborn environmental problems. Despite more than two decades of massive and costly efforts to bring this problem under control, the lack of ozone abate- ment progress in many areas of the country has been discouraging and perplexing." (NRC, 1991, p. vii). Ozone (O3) is formed in the atmosphere through photochemical reac- tion. The primary emitted gaseous species contributing to ozone formation are nitrogen oxides (NOx = NO + NO2) and volatile organic compounds (VOCs), including hydrocarbons and oxygenated hydrocarbons. The gov- erning atmospheric chemistry is exceedingly complex. This complexity, which involves numerous interactions among pollutants, has hindered the development of an understanding of the most effective paths to reducing ambient ozone concentrations. Inadequate and inaccurate portrayal of emis- sions from both manmade and biogenic sources has also contributed to difficulties in developing successful emissions control strategies. Although more information and improved understanding is definitely needed, mitiga- tive actions have been taken and they continue. In this paper, we survey the regulatory framework that has been put into place over the past two decades to reduce ambient ozone concentrations, consider six pivotal issues underpinning this framework, and examine the interplay between regulation and the development of science and technol .~ 39

40 ROTH, ZIMAN, AND FINE ogy. We then attempt to extract some general conclusions that may be of value in future efforts to accommodate scientific developments in the regu- latory process. A BRIEF HISTORY OF OZONE LEGISLATION AND REGULATION In 1963 the Clean Air Act was enacted "to protect the Nation's air resources to promote the public health and welfare." It established "the prevention and control of air pollution at its source as the primary responsi- bility of the State and local governments." Federal leadership and financial assistance was requested to initiate research and development programs and to assist state and local air pollution control planning. Although the Depart- ment of Health, Education, and Welfare was authorized to execute the pro- visions of the act and to "recommend" air pollution control criteria, only limited enforcement authority was given to government agencies. Subse- quent amendments made in the late 1960s clarified provisions such as those pertaining to federal grants for research and air pollution control programs. However, the extent to which government would regulate air quality control and planning was not delineated until the Clean Air Amendments of 1970 were adopted. The 1970 Amendments The 1970 amendments required the Environmental Protection Agency (EPA) to "publish proposed regulations prescribing a national ambient air quality standard (NAAQS)" that defined unhealthy concentrations of spe- cific pollutants in ambient air (criteria pollutants). The "criteria" pollutants addressed in the NAAQS had been identified in the Air Quality Act of 1967 on the basis of existing information on the health effects of air pollutant concentrations. They included particulate matter, nitrogen dioxide, sulfur oxides, carbon monoxide, hydrocarbons, and photochemical oxidants, which were redefined as ozone when the standard was changed in 1979 from 0.08 parts per million (ppm) to 0.12 ppm. A NAAQS was later promulgated for lead. In the mid-1980s, the NAAQS for hydrocarbons was rescinded. The 1970 amendments required that state implementation plans (SIPs) be prepared to demonstrate attainment of the NAAQSs by 1975. The plans were to be prepared by every state having one or more nonattainment areas and submitted to the EPA for approval. Should a SIP not be prepared or approved, the 1970 amendments required a federal implementation plan (FIP). The implementation plans were to focus on the reduction of criteria pollutants, and in the case of ozone, on one of its precursors, VOCs. These reductions were to be accomplished by regulating mobile and stationary . ~

TROPOSPHERIC OZONE 4 .1 sources of pollutants. Although the 1970 amendments suggested control programs to be instituted by the states in attaining the NAAQS, specific requirements for SIPs were not set out until the 1977 amendments were adopted. As mandated by the 1970 amendments, the EPA was required to pro- duce a list of stationary source categories to be regulated under new source performance standards (NSPSs). The NSPSs were defined by the EPA on the basis of the availability of implementable technology. New major sta- tionary sources were defined as having the potential to emit 100 or more tons per year of a criteria air pollutant, or hydrocarbons in the case of ozone, and were required to apply the NSPSs. "Hazardous air pollutants," that is, pollutants not included in the NAAQS criteria but deemed by the EPA to cause irreversible harmful health effects, were also authorized for regulation under the 1970 amendments. Emissions of pollutants from mo- bile sources were to have been reduced by 90 percent from a 1970 baseline by 1975 for VOCs and carbon monoxide (CO), and by 1976 for NOX under these amendments. At this time, the EPA elected to institute an approach to air quality improvement that focused on managing the air resource by selectively con- trolling emissions rather than imposing control technology requirements on a full range of source categories. The EPA directed that plans for air quality improvement be drafted and implemented, using air quality simula- tion models to estimate the nature, amount, and distribution of controls needed to attain the standards. While modeling was required, models generally were inadequate or nonexistent; the gap between need and availability was siz- able. The 1977 Amendments The 1970 amendments established a framework for federal, state, and local agencies to regulate emissions of air pollutants and called for the EPA to establish specific air quality standards. Yet, by 1975-the deadline for attainment of the NAAQS many regions of the country still had not at- tained the standards. The 1977 amendments attempted to achieve attain- ment through stricter and more extensive control of emissions from new and existing stationary sources and through sanctions for failing to comply with provisions of the act. For example, nonattainment areas and states not preparing or implementing SIPs were potentially subject to EPA sanctions, which can include a ban on new major stationary source construction or deletion of EPA grant funds. By necessity, the 1977 amendments extended the attainment deadlines from 1975 to 1982 and included possible exten- sions through 1987 for ozone and CO, depending on the feasibility of at- tainment in some areas. .~

42 ROTH, ZIMAN, AND FINE In 1977, additional legislation concerned with the permit process for major stationary sources of nonattainment pollutants was passed as part of Part D, Title I (Plan Requirements for Nonattainment Areas) of the 1977 amendments. In ozone nonattainment regions, new source review (NSR) of new major sources of VOC emissions was required to ensure that the sources employed lowest achievable emission rate (LAER) practices and offset any increases in emissions by equivalent reductions in emissions within the nonattainment area. Existing major stationary sources, which had not been previously regulated under federal mandate, were required to retrofit equip- ment with reasonably available control technology (RACT). RACT and NSR were applicable only to VOC, not NOX, under the federal legislation. Because the 1970 goal of a 90 percent reduction had not been met, the 1977 amendments established a new schedule for decreasing tailpipe emis- sions mobile sources. To reduce on-road vehicles' emissions that were caused by deterioration of the on-board controls, ozone nonattainment areas that applied for an extension of the attainment date to 1987 had to institute vehicle inspection and maintenance programs. In the mid-1970s the EPA's process for reviewing the scientific basis for the NAAQSs was questioned. The 1977 amendments established the Clean Air Scientific Advisory Committee (CASAC) to review new scientific infor- mation and establish criteria on which the EPA would base changes to the NAAQSs if needed. The amendments also established a mandatory five- year review period for the NAAQSs and clarified the period during which the public would be able to comment on proposed changes to air quality standards. By the mid-1980s it became clear that few areas would actually meet the December 31, 1987, attainment deadline for the ozone standard. The EPA's response was to propose a policy that addressed post-1987 attainment issues. The policy was based on the premise that states would be submit- ting new plans to demonstrate expeditious attainment. The proposal is of interest now for its content: it attempted to incorporate the latest technical and scientific information pertaining to ozone formation. It included guid- ance on air quality modeling and, for the first time, it addressed the poten- tial need to reduce NOX emissions as well as, or in lieu of, VOC emissions. However, the EPA never finalized the policy. The authority of the agency to pursue the policy was questioned, and Congress became enmeshed in debate over reauthorization of the act. The 1990 Amendments By 1990 some 100 areas were still classified as nonattainment for ozone, based on the fourth highest ozone concentration measured in each area for the most recent three-year period (1987-1989~. This measured concentra \

TROPOSPHERIC OZONE 43 lion is known as the design value. Like the 1977 amendments, the main portions of the 1990 amendments that related to nonattainment areas were directed at the ozone problem. To define regulations commensurate with the degree of nonattainment, the 1990 amendments categorized ozone nonattainment areas as extreme, severe, serious, moderate, or marginal, based on their design values: Dead- lines for attainment were set according to severity. Regulations required reasonable progress toward attainment, to be achieved through a 15 percent reduction in VOC emissions for the first six years (through 1996), followed by 3 percent per year thereafter. However, the post-1996 reduction could be satisfied by substituting a reduction of NOx emissions for some or all of the VOC reductions after demonstrating that reducing NOx would be as effec- tive as reducing VOC emissions. The definition of a "major source" was adjusted according to nonattainment categories to increase the number of sources subject to NSR and RACT regulations set forth in the act. Whereas the 1977 amendments defined a major source as one that emitted at least 100 tons of VOCs annually, the 1990 amendments lowered criteria for defining major sources in severe and serious areas to 25 and 50 tons per year of VOCs, respectively. In Los Angeles, the only area classified as extreme, a major source is any source that emits at least 10 tons of VOCs per year. In addition to an increase in the number of new sources regulated by RACT and LAER requirements, the offset requirement was increased from a ratio of 1:1 to as high as a ratio of 1:1.5 in Los Angeles. To reduce mobile source emissions within nonattainment areas, the 1990 amendments expanded the requirements for emissions reductions to include producers of vehicle fuels as well as vehicle manufacturers. In addition to instituting an enhanced vehicle inspection and maintenance program for serious, severe, and extreme areas, the 1990 amendments mandated vapor recovery programs in fuel transfers (e.g., at gas pumps), set stricter stan- dards for tailpipe emissions, and required a reduction in fuel vapor pressure. Alternative fuels are encouraged, and clean-burning fuels are required for fleet vehicles operating in serious, severe, or extreme ozone nonattainment areas. Reformulated gasolines with a 2 percent by weight oxygen content are required for all vehicles for the nine cities with the worst ozone prob- lems. The EPA's authority to impose sanctions for noncompliance with SIP criteria was modified in the 1990 amendments to include 2:1 offsets for new stationary sources. However, the agency's authority to impose construction bans was withdrawn in these amendments. The amendments also estab- lished penalties if a region failed to make reasonable progress toward attain- ment and included provisions to move any nonattaining area into the next higher category if it did not meet the attainment deadline.

44 ROTH, ZIMAN, AND FINE The amendments recognized that ambient air quality problems are not restricted to consolidated metropolitan statistical areas (CMSAs), which had previously been used to define ozone air quality regions. Specifically, an 11-state transport region was created under mandate in the Northeast; this jurisdiction is to address nonattainment issues associated with the entire region. Other transport regions may also be formed by mutual agreement of the states that would be part of the region and with the concurrence of EPA. The 1990 Title III amendments increased to 189 the number of com- pounds identified as air toxics and mandated their reduction through new control requirements maximum achievable control technology (MACT). Because some of the largest emissions of the identified air tonics, such as benzene, are hydrocarbons, the MACT requirement will supplement the VOC reductions imposed by Title I. Also, NOX reductions required by Title IV, Acid Deposition, may aid in reducing ozone. Regulations controlling NOX emissions from stationary sources were enacted for the first time. Coal-fired utilities, which produced 33 percent of NOX emissions in 1989, are required to meet mandated emissions limits through the use of low-NOx burner technology. By the year 2000 this technology should reduce emissions by two million tons from the 1980 level. This requirement, in effect, supplements those for mobile source con- trols specified for NOX in Title II and for overall emissions in Title I of the 1990 amendments. See Tables 1 and 2 for a summary of legislative and regulatory history. California Regulation In the 1970 amendments, all the states, except California, were barred from enacting separate mobile source regulations. California was excepted because it had historically pioneered air quality regulation and programs. The state began to address air quality issues on a local level in the 1940s when the term "smog" was first used in Los Angeles. In 1947 the Califor- nia Air Pollution Control Act was passed. It established air pollution con- trol districts within each county and empowered the districts to control emissions through a permitting process. Because the Los Angeles Air Pol- lution Control District was the first agency to confront the smog problem, it became a leader in controlling sources of pollutants. The district, along with the Public Health Department, attempted to introduce state control of motor vehicle emissions as early as 1958. The California Motor Vehicle Pollution Control Act created the Motor Vehicle Pollution Control Board in 1960, which was eventually replaced by the California Air Resources Board (CARB). Since its formation, the CARB has consistently been one of the nation's most influential and innovative regulatory agencies. "The board lays down ....

45 By o · ~ - c) o As a: 'e a) ~ - o o c) o o v o He o Ha ~ - x ;> ~ - - u: ~ - By so: to As - a: - u: ~5 to o As c) o v, As - ~o v o .-o ~ An ~ a) 'e ~ v 4- ~ ~ o cD ~ c~ - ~ ce o ~ ~ - s: ¢ c) · ;^ ~ - ~ 3 , - ,~ C~ C: ._ ", D c<S ~ 5 C~ C~ ;^ C~ ._ ~ _ ._ Ct X 3 ~ O o _ s~ ~ Cd Ct ~ . ~ ,.= C> e ~ 5 -0 U: . ~n o 50 _~ ~N - - Cd X tz Oz C<S : - ~ _ O 1 1 C~ ~ ~ ~. O e~ o ._ U, ._ ~1 ~ ~1 . _ ;> Ct . o o ~: O ~ ._ c,, _ oo S: O ~ C.) O ~ ~ o 1 Ct C) Ct ~Q o ._ ._ Ct C) . _ ~s: .= ;> Ct Ct CC O _ ._ C) U~ . _ Cq C) O c,, o ._ ~ _ . o ~ O o o U, O O . _ U~ C~ . _ .= O ~ ._ C~ · ~ CO O .0 ~ C~ O ~ ~ ._ ~i ~ · C) C~ 3 2) Cq ._ ~ ^ s~ ~ O [_ ~ a~ U: D o - ;^ Cq C) - ._ ;> C~ - C) . o ._ &, C cn ._ _ . _ ._ _ S: Ct . O C~ Ct ~ Ct Ct ~ 00, 0 ~ ,= O4 - Ct ;^ Q ct D Ct D O O Ct 2 C~ o ._ ~ 3 ~ ;> o C~ o ;> o z . Cq C) o C~ ,~ ~ E~ - V ._ X ~ _ U:) ~ ~ o ~ C.;' ° tV - ~ (,, ~ X ~ ._ rT1 ~ ~ ;> C~ C~ Ct C) ~ ~ C) o C~ U, ~L) {-o. 7 ~ C.) · ~ U, - _ C) O ~ ~ ._ O ~ C~ 3 ~ ~ ._ ~ 3 E ~.O ;> ~4 - o ~o C) s~ . o _ Ct Cq - 50 o '~ ~ 3 cq C ~ ~ o o ~ U:) ~ c) V) ~ z 3 o · C~ O O ,,, 3 ~ o ~ ,- ~V ~ ° U, . o _) 3 ~ ~ o 50 ~ o V) V) Ct ~ - o C~ C~ D ~: ._ ;^ - ._ C) - Ct V) z Ct ;> O ~: C) Ct C~ ~ C~ 3 ~ o ~ - o C.:) - ._ C~ U, C~ ~: _ o (', ~ ~ O ~ C~ ~ ~ o ~ ._ o ,., o C) 4_ ~ Ct o C) C~ L~ ¢

46 s . ~ s . ~ .. Cal L o - C~ L L - C~ L L o a~ - ;^ o 00 V 3 o C~ cn L Ct r - o L ~ ~_ ~ · _ O O ) U: ~O I ~ O ~L -) ~,~, Ct ~3 o C Ce ~ C) ~ - 0 ~ ~Z · C ~e u: e ~e A ~ U. ~: ~O _ ._ C) U ._ C~ ,.~., · - ~L) O =, ~0 ·= ._ Ct e ~ ~ O ° O O C~ O ° [_ 0 ·- a~ ~ ._ _ ~ ~ Cl ~2 O ~ ~ ~ ax . _ ~ e ~ _ ~ ._ ~D o X o z C~ Ct S~ ~ - ct o z o o ~: ~- kAL) C~ ~_ 5 bC ._ Ct o~ ~At~ ~O ~O 11~ ~._ ;>;> . _. _ C~Ct C~_ . _Cq ao 11_) .. O V UO L o r~ - C~ o - o ·~? c,<) O S: O kL) .- ~ ~ O e ~ . - o C~ U, ~ O C~ ct ~L _ c5 O ~O ~ Ct O O ~ C~ ~ _ O COC C ~ ~O ~ e Z e C~ Ct ~. _ V) ~ O' E L) Z ._ ;^ Ct ~ s~ _ o o C: ~ . _ O C ~·g ~ , V) U~ . ~, . ~V ~L C~ ~ ~ e e ~e U, L - L o ._ C~ ._ V) e

TROPOSPHERIC OZONE 47 the toughest regulations, forces the biggest changes and generally blazes the path for everyone else, including the U.S. EPA," according to Matthew Wald (1992~. Emission controls for nitrogen oxides were promoted by the CARB almost a decade earlier than similar efforts were undertaken by the federal government. The state ambient air quality standards for ozone and fine particulate matter (less than 10 microns in diameter-PM 10) are much more stringent than the equivalent federal standards. Requirements for ad- ditional automotive emission controls led to the development of catalytic converters, cleaner burning diesel fuels, and more efficient ignition systems in motorcycles. Other CARB programs upon which federal programs were based include reductions in VOC emissions from fuel transfer systems and solvents and propellants. The CARB has recently introduced a low-emis- sion vehicle (LEV) program intended to dramatically reduce pollutant emis- sions from vehicles. The agency has also regulated emissions from small utility engines. Many of the CARB's actions have stimulated other state agencies and the federal government to consider or enact similar require- ments. PIVOTAL ISSUES IN FORMULATING REGULATIONS This section addresses six key issues that have, or should have, moti- vated regulation. For each, we describe the evolution of understanding over the past two decades, discuss how the issue has been addressed in the regulatory process, and examine the extent to which available knowledge has been reflected in regulation. Formulation of the Standard . What is an appropriate air quality standard for ozone, in terms of concentration and averaging time? Setting the Original Standard The 1970 amendments to the Clean Air Act mandated that the EPA set primary and secondary air quality standards for the concentrations of oxi- dants in ambient air. The primary standard was to serve as a regulatory reference for defining acceptably clean air. Oxidants and other pollutant standards were defined to be those which "in the judgment of the [EPA] Administrator, . . . allowing for an adequate margin of safety, are requisite to protect human health." (The secondary standard, which we will not address here, is "requisite to protect the public welfare." The prevailing primary and secondary standards for ozone are quantitatively equal.) Be- cause of the intrinsic uncertainties associated with the definition of criteria

48 ROTH, ZIMAN, AND FINE used in establishing the standard, the dearth of substantiating scientific data, and the health and economic implications of the standard, the standard setting process has been mired in controversy from the outset. The criteria used to establish the standard were difficult to define. The term "threshold" referred to the oxidant concentration at which exposure results in an "adverse health effect." Yet, the degree and type of health effects occurring in clinical tests vary depending on the subject (Federal Register EFR], Vol. 44, February 8, 1979), resulting in a range of ozone concentrations at which adverse health effects occur, rather than a threshold (Landy et al., 1990~. The EPA noted this fundamental point of confusion: "the adverse health effect threshold concentration cannot be identified with certainty" (FR, Vol. 44, February 8, 1979~. Moreover, the concept of a threshold implies the level of a measure at which no health effect occurs, which, by virtue of this property, is inherently difficult to determine. As a consequence of this dilemma, establishing the human response that barely constitutes an "adverse health effect" was less a scientific observation than a policy decision (Landy et al., 19901. In short, identification of a threshold appears to be an unavoidably uncertain determination. Some believe that it is appropriate to identify and protect the most sensitive population group when establishing a standard because reactions to oxidants depend on the sensitivity of an individual. In 1971 the focus was on asthmatics (FR, Vol. 36, April 30, 1971), but subsequent research has suggested that other groups, such as children and the elderly, may be more sensitive because of physiological characteristics or exposure frequency (Lippmann, 19891. Adding to the uncertainty were the criteria for a "margin of safety." An adequate margin could not be defined on the basis of scientific data. Rather, the EPA had to make a value judgment (Landy et al., 1990~. In addition, the scientific community did not have a complete understanding of the signifi- cance of long- versus short-term exposure to air pollutants (Lippmann, 1989~. Thus, it was difficult to define a time increment for measuring oxidant con- centrations the "averaging time." Defining an averaging time, a margin of safety, the most sensitive group, adverse health effects, and an oxidant thresh- old concentration required making assumptions founded in uncertainty. In 1970 and 1971 the EPA conducted an intensive review of the health effects literature. Virtually all the studies reviewed failed to provide defini- tive information on the health effects of ozone at low concentrations. After much consideration, the EPA determined that a study conducted by Schoettlin and Landau (1961) provided the most acceptable scientific basis for setting an oxidant standard (FR, Vol. 36, April 30, 19711. This study reported an increased incidence of asthmatic attacks on days when the ozone concentra- tion exceeded 0.10 ppm. Obviously, a single study could not provide suffi- cient information upon which to base an ozone standard. The EPA was .'

TROPOSPHERIC OZONE 49 aware of this but was nevertheless required to set a standard by the 1970 CAAAs. The paucity of available information meant that the EPA had to make a policy decision concerning the threshold at which health effects occur (Landy et al., 1990~. When the EPA selected a standard of 0.08 parts per million of photochemical oxidant (later changed to ozone) in ambient air measured over a 1-hour period, a debate ensued over its adequacy and appropriateness. The controversy reflected concerns about uncertainties in defining the standard, skepticism about its scientific basis, and the health and economic implications of the policy decision. Although the EPA wrote, "the Clean Air Act does not permit any factors other than health to be taken into account in setting the primary standards" (FR, Vol. 36, April 30, 1971), special interest groups aligned themselves on either side of the issue. Those likely to be burdened with the cost of attainment industry and municipalities faced with air quality problems- were critical of what they viewed as an overly protective standard. Envi- ronmental groups supported the 0.08 ppm standard, or an even tighter stan- dard. When a review of the Schoettlin and Landau study, conducted at the request of industry, revealed suspicions about the results, the scientific basis for the standard became questionable (Landy et al., 1990~. Revising the Standard The need for a formal scientific review to support the EPA was ac- knowledged by legislation in the 1977 CAAAs. The Clean Air Scientific Advisory Committee was established to review new scientific findings for inclusion in a "criteria document," which was intended to centralize all current information related to research on the health effects of ozone and to provide the CASAC's recommendation regarding an appropriate threshold. (Criteria documents had been prepared before 1977 as well.) It was to be the document upon which the EPA would base standards. In addition to the CASAC's input, the 1977 CAAAs mandated a public comment period and mandatory review of the standard every five years. Scientific information on the health effects of ozone, based on clinical tests on humans and animals and on epidemiological studies, was expanded during the mid-1970s (see Landy et al., 1990~. Four clinical studies (Delucia and Adams, 1977; Hackney, 1975; Linn, 1978; and von Nieding, 1977) provided contradictory results. Two suggested that health effects occurred at ozone concentrations of 0.15 ppm in healthy young men, whereas the remaining two showed no effects in asthmatics and young men at levels of 0.20 ppm and 0.25 ppm, respectively. In reviewing the standard-setting process, Melnicl; (1983) observed that the Delucia and Adams study was "the single most important clinical evidence relied upon by the EPA" when recommending a revised standard. While those advocating a more relaxed ..

so ROTH, ZIMAN, AND FINE standard argued that studies showing health effects at ozone concentration levels of 0.20 ppm and 0.25 ppm should be given equal consideration, EPA administrators were more concerned with studies showing health effects at low levels of ozone concentration because they felt they had a legal obliga- tion to set precautionary standards (Melnick, 1983~. In addition to clinical studies, at least seven epidemiological studies were conducted in Japan and the United States. These results were suspect, however, because of the lack of controls employed in the experiments and the difficulty of applying the results to setting ozone thresholds. Also, while several animal studies had been conducted, there was no method for relating these results to human health. Scientific information in the late 1970s, though more expansive, was neither complete nor definitive. Most studies were inappropriate for sup- porting policy decisions because of ambiguous results (Landy et al., 19904. Consequently, the CASAC was faced with uncertainties similar to those that the EPA had faced earlier in defining criteria for the standards. Defining the most sensitive group, "adverse health effects," a margin of safety, and the threshold value continued to pose problems, as they had during stan- dard-setting carried out in 1971. The role of the CASAC was further com- plicated by a renewed emphasis on the economic feasibility of implement- ing the standard. Although apparently dismissed in the 1970 CAAAs, economic concerns resurfaced in the political climate of the late 1970s. President Carter stressed cost-benefit analysis in justifying government regulation, and he created the Regulatory Analysis Review Group (RARG) to analyze the economic impact of government regulations (Landy et al., 1990~. At the same time, the Science Advisory Board (SAB), of which the CASAC is a part, was asked by the EPA administrator to review the criteria document. In fact, the board served as an important critic of all three drafts of the criteria document presented by the EPA. Also, the Advisory Panel on Health Effects of Photochemical Oxidants (known as the "Shy Panel") and a team of decision science analysts were convened by the Office of Air Qual- ity Planning and Standards to recommend alternative levels of a standard, with rationales, to the EPA administrator (Landy et al., 1990; Melnick, 1983~. To critique the criteria document constructively, each group had to address and resolve uncertainties associated with the information used in setting the standard. (The EPA, the SAB, and thus the CASAC were them- selves barred from considering economics in their deliberations.) While the Shy Panel and decision science analysts recommended a standard of 0.08 and 0.15 ppm, respectively, the SAB advocated relaxing the standard to the degree supported by industry. Ultimately, the EPA did not incorporate the opinion of the SAB into its suggested ozone standard. In 1978 the EPA's Office of Research and Development (ORD) pre- pared a criteria document in which health effects were judged to occur ..

TROPOSPHERIC OZONE 51 potentially in sensitive persons at exposure levels of 0.10 ppm (Landy et al., 1990~. Although the document recognized that the "lowest observable ad- verse effects levels" (LOAEL) had not been observed in any clinical studies on humans at exposure levels below 0.15 ppm ozone, it noted experiments showing respiratory infection in animals, and possible interactive effects involving other air pollutants. The OAQPS's Shy Panel and risk assessment analyses supported the 0.15 ppm ozone concentration as the threshold point for health effects. However, the SAB never approved this version of the criteria document because its members believed the conclusions were based too heavily on flawed studies indicating health effects below 0.25 ppm ozone concentration, such as the Delucia and Adams study (Melnick, 19831. Soon after the release of the criteria document, the EPA recommended that the standard be relaxed to 0.10 ppm. At the ensuing series of public hearings, the American Petroleum Institute (API) suggested a 0.25 ppm ozone standard based on the "lack of firm evidence of significant adverse health effects near the proposed standard." In contrast, the American Lung Association and Environmental Defense Fund argued that the exposure to concentrations of 0.08 ppm ozone had not been proven safe. In addition, concerns about the cost of implementing an overly conservative standard led RARG to recommend an ozone concentration standard of 0.14 ppm. (See Landy et al., 1990, for a summary of the various responses.) Clearly, as Melnick (1983) summarized, "the answer to the question of where health effects begin usually depends on whom you ask." The EPA administrator eventually selected a "compromise" standard of 0.12 ppm incorporating a 1-hour averaging time. According to Melnick (1983), this represented a health effects threshold of 0.15 plus a 20 percent margin of safety. Although the criteria document identified options for the EPA administrator to consider, including a more conservative formulation, the EPA administrator had to consider public policy issues and feasibility of implementation. Considering the uncertainties surrounding definition of the standard and the incompleteness of scientific information, the administrator could conclusively identify only a range in concentration rather than a spe- cific concentration level. In the end, as Douglas Costle, the administrator, later stated, selection of the concentration level "was a value judgement" (Landy et al., 19901. The role of scientific information in the selection process was further put into perspective when, during the 1988 review of the standard, the EPA wrote: Although scientific literature supports the conclusion that particular ozone concentrations and exposure patterns may pose risks to human health, sci- entific data can only identify the limits of a range within which a standard should be set. Specific numeric standard levels, frequency of allowable exceedances, and averaging times are largely a public policy judgement (EPA, 1988, p. viii-81. _ _

52 Subsequent Review of the Standard ROTH, ZIMAN, AND FINE Numerous new studies have been published that provide additional sci- entific data related to setting ozone concentration standards. Lippmann (1989) cites 110 studies published between 1979 and 1988 in "Health Ef- fects of Ozone: A Critical Review," observing that "we . . . know a great deal about some of the health effects of ozone." Still, uncertainty is an important factor in selection of the ozone standard. The concept of a threshold is intrinsically difficult to define, as admitted by both the EPA and the scientific community (Landy et al., 19901. In addition, an adequate margin of safety has not yet been established. The CASAC did reach consensus on the definition of adverse health effects, which are described in Lippmann (19891. Sensitive population groups are also further defined; they include asthmatics and people who regularly exercise outside. In 1988 only half of the members of the CASAC believed the current ozone standard was adequate to protect human health (Lippmann, 1989~. The significant existing concerns relate to averaging time. Until recently, concerns over averaging time have been usurped by the larger issue of ambient air concentration thresholds. However, recent scientific data indi- cate that the effects of long-term exposure to low concentrations of ozone may have greater adverse health effects than short-term exposure at peak concentrations (Lippmann, 19891. Effects from exposure to ozone have also been shown to become progressively more significant as the duration of exposure increases (Lippmann, 1991~. The need to develop further scien- tific data on these potential health effects has been pointed out by the CASAC. The EPA confirmed the need for additional research when, in its summary report on the 1988 review of the ozone standards, it stated, the review of the need for longer-term tozone] standards by EPA should be continued. Because there is a good data base available on 1-2 hour expo- sures, the staff recommends that review of this scientific information be closed out. With this portion of the review complete. .. the [EPA] Ad- ministrator will be in a position to make a regulatory decision on how and when to best act on the 1-hour standard (EPA, 1988, p. xi-6. Gathering additional scientific information on the long- and short-term health effects of ozone will have a twofold result. First, the need to revise or expand the 1-hour averaging time standard may be confirmed. Second, should such LOAEL be observed in longer averaging times, the ozone stan- dard may need to be tightened. As Lippmann observed after reviewing new scientific information in 1991: [bjecause the various transient effects on lung function are more directly proportional to cumulative daily exposure than to peak hourly concentra- tion, . . . the degree of protection provided by the current "standards] is much lower than previously believed (Lippmann, 1991, p. 1956~. .. ...

TROPOSPHERIC OZONE 53 As noted earlier, questions about the costs of attaining the present stan- dard arose during the standard revision process in 1978. However, it is difficult to evaluate the merits of incurring the costs of attainment unless the savings are compared with the associated benefits. Until recently, there were few attempts to quantify both sides of this complex equation, partly because methodologies for doing so were unavailable. Recently, two stud- ies have been published that attempt to make this comparison. Krupnick and Portney (1991) examined the costs associated with attaining the present standard in the Los Angeles Basin and concluded that they significantly outweighed the benefits. However, the authors were careful to note that uncertainties were rife in their estimates and that the study actually was intended to stimulate discussion: Finally, implicit in our discussion is discomfort with the premises on which our nations air quality standards are now based. If, as seems likely, there are no pollution concentrations at which safety can be assured, the real question in ambient standard setting is the amount of risk that we are willing to accept. This decision must be informed by economics. A1- though such economic considerations should never be allowed to dominate air pollution control decisions, it is inappropriate and unwise to exclude them (Krupnick and Portney, 1991, p. 527~. Hall et al. (1992) used a methodology developed under contract to the South Coast Air Quality Management District to make similar comparisons for ozone (as well as an assessment of PM-10) and estimated that the ben- efits of attaining the ozone standard would be $1.2 billion to $5.8 billion annually, with a best estimate of $2.7 billion. In presenting the implications of the study, the authors discuss the state of the methodology relative to policy decision making. One (implication) is that benefit estimation has not reached the maturity that policy-makers would like and cannot yet provide definitive answers to difficult economic questions (Hall et al., 1992, p. 8161. As Lippmann noted in the conclusion of his 1991 review, in reference to the need for a more definitive data base on the chronic effects of human exposure to ambient ozone: Further controls on exposure to ambient ozone will be extraordinarily ex- pensive, and will need to be very well justified .... It is therefore important that health scientists and control agency personnel understand the nature and extent of human exposure and the effects they produce to communicate health risks effectively to the public, and to help develop realistic priorities and feasible options for reducing human exposures (Lippmann, 1991, p. 19561.

54 ROTH, ZIMAN, AND FINE In 1990, Congress decided to preserve the present standard-setting pro- cess rather than to adopt an approach that explicitly takes into account both benefits and costs. However, some (e.g., Krupnick and Portney, 1991) argue that costs should be explicitly examined in the process of developing legislation. If this is to be done, Congress must confront two issues. First, methodologies for estimating benefits by assessing the cost savings of re- duced risks to health are likely to remain imprecise for some time. Second, and more important, a benefits-cost approach to valuing human life is likely to be perceived negatively by the public. In the past, Congress has been very reluctant to deal directly with the issue of "value of human life," and we should not expect a major shift now. Finally, as evidenced by the discussion of earlier efforts, the standard- setting process transcends scientific knowledge alone. The EPA administra- tor must also take into account a number of factors that affect the contem- plated legislation or are put into effect by it for example, the legal and sociological implications of a proposed change. The standard-setting pro- cess is not well defined. Decision making involves weighing many factors unique to the situation at hand; thus, the process does not lend itself to . A. . . . spec~cat~on a priors. The standard-setting process and its attendant problems illustrate the difficulties of formulating environmental legislation that includes unam- biguous information on anticipated effects or possible outcomes in circum- stances that are characterized by substantial uncertainties. The current state of knowledge seems never to be adequate; additional information is always needed. Nevertheless, decisions must be made. Science provides the clearest available statements of current knowledge, including uncertainties and in- formation gaps. This information is incorporated into legislation after policy deliberations that take into account socioeconomic factors and values, as well as knowledge. Emission Control Strategies · Should reductions in VOC or NOX emissions or both be favored in pursuing attainment of the ozone standard? Both VOCs and nitrogen oxides are emitted pollutants (actually, sets of pollutants) that participate in the atmospheric chemical reactions leading to the formation of ozone. For more than 20 years, VOCs have been the primary targets for emissions reduction. At various times during this pe- riod, however, the question of whether to focus on VOC reductions, NOX reductions, or both has been the subject of discussion and debate. The issue once again is receiving significant attention. Two main bodies of data the results of smog chamber experiments ..

TROPOSPHERIC OZONE 55 and examination of data collected at monitoring sites in several U.S. cit- ies led officials of the National,Air Pollution Control Administration (NAPCA) to conclude in 1970 that reduction of VOC emissions would be the appro- priate mechanism for effecting reductions in ambient ozone concentrations. Los Angeles officials believed that NOX controls should be implemented as well, on the basis of smog chamber studies carried out locally. NAPCA scientists questioned the reliability of these results and tended to dismiss their significance. Both the monitoring data and the federal chamber work were limited in extent and in accuracy because measurement methods and chamber techniques were still in evolution. Yet they constituted the pri- mary available evidence (personal communication with B. Dimitriades, 1992~. Other factors influenced decision making. Eye irritation experienced in the Los Angeles Basin was attributed to the presence of formaldehyde, acrolein, and possibly other organic compounds, and controlling VOCs would mitigate this insult. Cost analyses indicated that reducing VOCs would be less expensive, per ton of emissions, than reducing NOX. Methods that appeared effective in reducing VOC emissions from motor vehicles also appeared effective in reducing carbon monoxide emissions, another pollut- ant of concern. The net result was a determination that reduction of VOCs was the appropriate measure for reducing ambient ozone concentrations (personal communication with B. Dimitriades, 1992~. At an early stage in federal efforts to reduce precursor emissions, an ambiguity arose in control philosophy. The 1970 and 1977 CAAAs re- quired a 90 percent reduction in VOC and NOX emissions from motor ve- hicles. Legislators presumably saw "cleanup" of automotive emissions as an opportunity to challenge the automotive industry to reduce both precur- sors by developing novel control technology. However, this focus on con- trolling NOX as well as VOCs for motor vehicles did not carry over to stationary sources for some time: federal requirements for regulating NOX emissions from these sources were not instituted until 1990. (To be sure, NOX emissions from stationary sources often affect ozone control strategies quite differently than NOX emissions from mobile sources and surface sources in general. However, this issue seems not to have been explicitly addressed either.) In the mid-1970s the Bureau of Mines presented findings of smog chamber experiments in which auto exhaust was irradiated (Dimitriades, 1972~. The results suggested that, under conditions typifying ambient concentrations in urban areas, control of NOX emissions may lead to increases in ozone con- centrations, or at least reductions in the size of the decrease that would be achieved through control of VOCs alone. Although the EPA accepted these findings as evidence supporting its earlier policy decisions, criticism of this position followed. Primary concern focused on the tenuous technical basis for the so-called Appendix J curve (see Figure 1) a plot of ozone versus

56 100 In to= <3 80 E ~ a) lL ~ CL ~ C\5 ~ ~2 `i' ~ ~ ~ - 0 0 0 ~ ._ ~ ~ Cal I Z c) ~ a) ~ ._ ~ a) ~ a) ~ ·°= 0 20 c' ~ 0 ° ~ 60 40 o / - - - - - - - - 150 200 250 300 350 400 450 500 550 600 Maximum Measured 1-hour Photochemical Oxidant Concentration (pg/m3) FIGURE 1 "Appendix I" curve. Required hydrocarbon emission control as a func- tion of photochemical oxidant concentration. NOTE: No hydrocarbon or photo- chemical oxidant background assumed. SOURCE: Environmental Protection Agen- cy (1971). VOC concentrations for cities where such data were available (FR, Vol. 36, April 30, 1971~. Each point plotted represented the peak ozone and VOC concentrations for a city. The "Appendix J" curve was a nonlinear envelope that confined all plotted points below it; it thus was intended to represent an upper bound on feasible combinations of maximum VOC and ozone concen- trations. The plot suffered from several deficiencies. Data were available for only six cities. NOX data were virtually nonexistent; the data that were available were of questionable accuracy. (The VOC data were inaccurate as well.) Critics were concerned that conclusions were being drawn from inadequate evidence few data and weak analytical relationships. In short, Appendix J was viewed as being "too empirical" and very likely unreliable. The EPA's response to this criticism was the "son of Appendix J." the con- ceptual version of what was very soon to become the EKMA the empirical kinetic modeling approach (Dimitriades, 19771. During the last half of the 1970s, considerable effort was devoted to developing information about chemical reaction rates and product distribu- tions and to studying collective chemical dynamics in smog chambers. This information was used to estimate parameters for mathematical representa ...

TROPOSPHERIC OZONE 57 lions of atmospheric chemical dynamics (chemical mechanisms) that were under intense development (Atkinson and Lloyd, 1984~. The data were also used to evaluate the capabilities of mechanisms to emulate chamber obser- vations. These efforts produced substantially improved chemical mecha- nisms that were used in the EKMA and in photochemical models. The development of models capable of simulating the dynamics of at- mospheric processes that lead to ozone formation (commonly termed photo- chemical models, or "grid" models) began about 1970. By 1973 the EPA had committed its research efforts to supporting continued development of the Urban Airshed Model (UAM) (Reynolds et al., 1973~. The UAM, modi- fied a number of times, is the model currently designated for use by the agency (EPA, 1991~. The model saw very limited application solely in the Los Angeles Basin during the mid-1970s; more widespread and intense application began in 1979 and has continued to this day. Because the UAM was designed to simulate both meteorological and chemical processes and because it is both spatially and temporally resolved, it was judged a potentially more reliable simulator of atmospheric dynamics and ozone formation than its predecessors. By 1982 both the EKMA and UAM were recommended for use in specific applications; by 1986 the UAM use was generally favored whenever data were available to support the application. The EMMA models produce two-dimensional plots of VOC and NOX emissions, on which are drawn contours of constant peak ozone concentra- tions (see Figure 2~. The shapes of these contours at lower VOC and higher NOX emissions levels (see, for example, point A) indicate that decreases in VOC emissions will reduce peak ozone concentrations, but decreases in NOX emissions will have the opposite result. Urban Airshed Model simula- tions, using the same chemical mechanisms and taking into account full three-dimensional flow patterns as well, produced similar findings. Since a number of urban areas appeared to have "operating points" near or above "the ridge" in the diagram, EKMA modeling carried out from 1977 through 1982 generally supported VOC controls. However, the scientific commu- nity was aware of the uncertainties and limitations in modeling, of the limitations in aerometric data bases, and of the uncertainties in emissions representations: the evidence was incomplete. During the historical period under review, evidence was offered and concerns were expressed at various times about the potential merits of re- ducing NOX emissions. Results of chamber studies conducted by the Bu- reau of Mines in the mid-1970s indicated that at high ambient VOC/NOX ratios, it would be more beneficial to reduce NOX emissions (Dimitriades, 1977~. The EPA believed that these conditions prevailed in rural, not urban, areas. The agency's concern was the reduction of ambient ozone in popula- tion centers; VOC controls were expected to suffice in these critical areas. .. . ,

58 ROTH, ZIMAN, AND FINE Increasing Peak Ozone Concentration in o . _ to .E us x o of ....',,/ l l Contours of :_ Constant Peak _ _ 070n~ `./lc VOC Emissions FIGURE 2 Hypothetical ozone isopleth (EKMA) diagram. Once "EKMA diagrams" were generally accepted as being schemati- cally representative of the VOC-NOx-ozone system, they were used to dem- onstrate the potential merits of NOx control in areas where the "operating point" characteristic of the area was located "below the ridge," that is, at a location on the diagram (see Figure 2), such as point C. The problem lay in demonstrating that a particular urban area was characterized by a point "below the ridge." For most urban areas, data needed to support such a contention were either inadequate or lacking. Another general characteristic of the EKMA diagram for most urban areas is the more favorable "cost-benefit ratio" of implementing either NOx or VOC control alone, compared with that achieved by controlling both. The shape of the isopleths of constant ozone dictate that moving from an "operating point" (such as point A or C) toward the origin (combined con- trol) is always less efficient (or more costly) than moving parallel to either axis (control of one precursor or the other). Moreover, greater control of -

TROPOSPHERIC OZONE 59 VOC is needed to achieve a specified ozone concentration when NOX is reduced than when it is not. Thus, if air pollution in an urban area is of concern, the diagram suggests control of either, but not both, precursors. However, if there is reason to reduce emissions to mitigate another air pollution problem, such as PM-1O, the overall effectiveness of a strategy aimed at meeting two specified targets must be assessed; in this case, con- trol of both precursors may be preferred. The issue of overall effectiveness also arises in considering the transport of pollutants as well; "hybrid" con- trol strategies may be needed to meet both local and regional air quality goals. Evidence of a different nature supporting the potential benefits of NOX control in certain circumstances emerged during the mid-1980s. Trainer et al. (1987) found, through observations made during periods of elevated ozone concentrations in rural locations in Colorado, that NOX concentra- tions were very low. In such circumstances, control of VOC was likely to be ineffective; NOX control would be required in order to reduce ozone appreciably. In carrying out EKMA modeling for Atlanta, Chameides et al. (1988) found that when biogenic emissions were included in the inventory, the magnitude of VOC reductions needed to attain the ozone standard in- creased to a level surpassing the estimated NOX control requirement. In effect, the high biogenic emissions in the Southeast appear to elevate the ambient VOC/NOX to levels favoring NOX control over VOC control. At about this time, the congressional Office of Technology Assessment (OTA) issued a report entitled, Catching Our Breath (OTA, 1989) that ques- tioned whether VOC control was sufficient to ensure attainment of the ozone standard. From a series of analyses examining air quality in a large number of U.S. cities, the OTA concluded that [Llocal controls on VOC emissions cannot completely solve the Nation's ozone problem. New control methods will be needed, but looking beyond the traditional controls raises challenging new technical and political is- sues. One promising approach for some areas is controlling NOX, both locally and in areas upwind of certain nonattainment cities. In addition, the report stated that Congress might wish to require studies to determine which areas would indeed benefit from NOX controls. On the other hand, it may instead wish to require controls everywhere, but allow for exemptions in places where they are useless or counterproductive in reducing ozone (OTA, 1989, p. 201. During the period from 1989 to 1992, a series of disparate studies- monitoring, modeling, and data analyses strongly indicated that invento

60 ROTH, ZIMAN, AND FINE ries in California substantially understate overall VOC emissions, perhaps by a factor of two. These studies included measurements of VOC, NOX, and CO in the Van Nuys tunnel and comparison with emissions estimates (Ingalls et al., 1989), remote instantaneous roadside measurements of emissions from individual vehicles and analyses of data acquired during inspection of auto- mobiles in California (Lawson et al., 1990), analyses of ambient and emis- sions ratios (Fujita et al., 1992), UAM simulations carried out by CARB staff (Wagner and Wheeler, 1991), and photochemical air quality model simulations (Harley et al., 19921. The studies showed that understatement of VOC emissions appears to be in large part attributable to biases in esti- mated mobile source emissions. If, indeed, total VOC emissions have been underestimated by a factor of two or thereabouts (and boundary and initial onclition~ ore. maintained approximately the same), then correcting them would increase the emitted VOC/NOX by a similar factor, shifting the reac- tive mixture represented in models toward an NOx-lean environment and shifting relative emissions control benefits from VOC toward NOX. (In fact, either boundary conditions or initial conditions or both have probably been increased in modeling exercises within their ranges of uncertainty to compen- sate for the unrecognized underestimation of VOC emissions. Thus, one must determine the aggregate loading of emissions and initial and boundary condi- tions to establish the extent to which the estimated relative benefits of VOC versus NOX controls shift in correcting for underestimated VOC emissions.) Continuing work during the 1980s confirmed the inhibitory effect of NOX emissions controls in subregions near major source centers. Such findings merely heightened the dilemma: NOX controls appear to be benefi- cial in some conditions, detrimental in others. Currently, photochemical modeling (i.e., "the modeling system" a meteorological model, an air quality model, an emissions representation, and requisite supporting data) simply is not sufficiently reliable to establish unambiguously the circumstances and extent of benefit and detriment. Moreover, sufficient data are not available for most areas to make a reliable case through analysis. Thus, the debate continues. In densely populated, multiple-city regions such as the Northeast, pre- cursors and ozone can be transported from one metropolitan area to another, influencing pollutant formation in the downwind area. This situation is exceedingly complex and requires considerable study to gain a proper un- derstanding of control requirements. Work to date that has indicated the benefits of employing NOX controls for a range of circumstances is intrigu- ing. However, these results cannot be viewed as definitive because of the inadequacy of supporting data bases and certain restrictive assumptions as- sociated with the Regional Ozone Model (Reynolds et al., 1992~. In 1990 California enacted legislation that, if implemented, would man- date new standards for vehicle emissions and regulate all types of fuels in'

TROPOSPHERIC OZONE 61 equitably; permissible emissions limits are related to the "reactivity" of the fuel. California regulation is based on a reactivity adjustment factor (RAF), where RAF is equal to the ratio of (1) the amount of ozone formed per gram of tailpipe emissions of alternative fuel to (23 the amount of ozone formed per gram of tailpipe emissions of conventional gasoline in a comparable vehicle. While considerable attention is being given to developing reactivity factors in California, research being carried out at the University of North Carolina (Jeffries and Crouse, 1992) suggests that, in environments where the pool of free radical species is sufficient to promote and sustain reac- tions, about half of the total ambient ozone is formed through the oxidation of the least reactive species, notably methane, carbon monoxide, and paraf- finic hydrocarbons. At the same time, reactive, radical-forming species, such as formaldehyde, are needed to ensure the sufficiency of the radical pool. Results of continuing research may clarify the relative importance of reactivity in determining the contributions of VOC constituents to ozone formation. Should research findings indicate that less, as well as more reactive VOCs contribute significantly to ozone formation, this would sug- gest that it may be difficult to control adequately all sources of organic compounds because of their often high concentrations, ubiquitousness, and sometimes natural origins. An implied consequence of such an outcome is the need for NOX controls. In 1991 the National Research Council issued Rethinking the Ozone Problem in Urban and Regional Air Pollution. In that report (p. 11), the authors state that "to substantially reduce ozone concentrations in many urban, suburban, and rural areas of the United States, the control of NOX emissions will probably be necessary in addition to, or instead of, the con- trol of VOCs." Considering the findings of past studies, areas likely to benefit from NOX control include rural areas (very low NOX concentrations), regions having high levels of biogenic emissions (such as the Southeast), and cities where industrial emissions of VOCs are high. In addition, NOX controls may be beneficial in urban areas that are located in a multicity "high ozone" region that experiences long distance transport. However, atmospheric dynamics and emissions patterns, including biogenics, at the regional scale merit considerable study before conclusions are reached. The NRC report has rekindled and refueled the VOC versus NOX debate; the issue is stimulating vigorous inquiry. This discussion points out the lack of clarity that has plagued the VOC versus NOX controversy for nearly two decades. Although the debate resurges from time to time, the EPA has basically promoted VOC control as the principal path to attaining the ozone standard, with two main exceptions. First, as previously noted, in both the 1970 and 1977 amendments Congress mandated 90 percent reductions in NOX, as well as VOCs from motor ve _~

62 ROTH, ZIMAN, AND FINE hicles. Second, in Title I of the 1990 amendments, Congress mandated 15 percent reductions in VOCs over the first six-year period and 3 percent reductions per year of some combination of VOC and NOX thereafter until the area attains the ozone standard. During the post-1996 period, NOX reductions can be substituted for some or all of the VOCs. Furthermore, Title I, Section 1 82(f), requires implementation of NOX controls, RACT, and NSR for stationary sources for urban areas classified as extreme, severe, serious, and moderate for ozone-related air pollution, unless the administra- tor determines that some or all reductions in NOX would not contribute to attainment or would not result in either net air quality or ozone benefits. (Note that the possibility of exempting NOX does not extend to VOCs. Should reductions in VOC emissions prove to be not beneficial for an area, the reductions must still be made. Thus, the 1990 amendments reflect a bias toward VOC control.) Congress also required a reduction of two mil- lion tons per year in NOX emissions from fossil-fuel-fired power generating stations. Although this Title IV requirement is motivated by a desire to reduce the deposition of nitric acid, it also reduces the amount of NO available for participating in ozone formation. Studies conducted or reported beginning in the mid-1980s appear to have had the greatest influence in promoting the inclusion of NOX emissions reductions in the 1990 amendments. Until that time, evidence supporting NOX controls appears to have been viewed as either weak or unreliable. Thus, NOX emissions from stationary sources remained unregulated at the national level for two decades. (NOX emissions from stationary sources have been regulated in California for over a decade through a long series of rulemakings. CARB pursued this alternative course in the belief that attain- ment of the standard could not be achieved in the state without taking such actions.) However, as of this writing, the merits of NOX controls are not well established. For example, Wagner et al. (1992) found, through a com- prehensive series of sensitivity runs, that NOX controls do not appear to contribute to reductions in ozone concentrations and population exposure in the South Coast (Los Angeles) Air Basin. In summary, available evidence suggests that there is no current justifi- cation for regarding either VOC or NOX control as being generally more effective. At the same time, the traditional case-by-case approach that pre- vailed prior to 1990 has been replaced by one in which presumptive controls are mandated, but the NOX component can be altered in accordance with area-specific modeling results and other related evidence. Range of Objectives · Should controls of VOCs and NOX be based on a desire to reduce PM-10, visibility impairment, and acidity as well as ozone? - ...

TROPOSPHERIC OZONE 63 · Should planning for improving air quality, focusing on all elements, be integrated? If so, is integration feasible? Volatile organic compounds, NOX, and sulfur oxides (SOX = SO2 + SO3) are precursors to the formation of suspended particles (PM-10 and PM-2.5), atmospheric acidity and acidic deposition, and impairment of visibility, as well as to ozone and other atmospheric oxidants. Nitrogen oxides and other pollutants influence free radical concentrations and thus atmospheric chem- istry in general, as well as the concentrations of free tropospheric ozone, a greenhouse gas. Despite these interrelationships among pollutants, exami- nation of issues and the making of regulations has, for the most part, oc- curred without serious consideration of the linkages. In most instances, ozone and oxidants, SO2 and sulfates, acidic deposition, and fine particles have been examined separately. The exceptions include linking acidic deposition and sulfur oxides since 1980 (SOX was treated alone before that time) and linking visibility impairment and fine particles. Proper attention to the interrelationships can influence the development of long-term emissions control strategies. For example, a reluctance to reduce NO emissions in order to attain the ozone standard might be coun tered by a desire to reduce NOX to lessen acidic deposition or formation of fine particles. One might speculate that, were interpollutant issues treated as such through the 1980s, attention would have been given to the merits of NOX control at an earlier date. In the late 1960s, the NAPCA identified ozone and oxidants, CO, par- ticulate matter, hydrocarbons, SO2, and NO2 as criteria pollutants. "Criteria documents" were drafted for each. State or federal implementation plans Generally addressed control strategies separately for each secondary nonattain ~ ,, ~ ~ J ~ . ~ 1 . . ~ · ~ ~ . . . ~ . . 1 1 . ~ ~ ment pollutant (l.e., a pollutant not directly emitted, but formed in the atmosphere through chemical reaction) and its precursors. In effect, this artificially disentangled one reactive system from the other. Existing links generally received only passing attention, or they were ignored. This ap- proach persists today. No rules prevent an agency from preparing an SIP or FIP that examines and respects the linkages. Even though a historical precedent has not been established, the vehicle for such examination exists. Both Catching Our Breath (OTA, 1989) and Title IX of the 1990 amendments recognize the need to establish links and interactions. The OTA notes that ''NOX emis- sions affect more than just nonattainment area ozone concentrations, further complicating the decision about whether to mandate controls. NOX emis- sions contribute to acid deposition." Title IX directs that the administrator of the EPA "shall conduct a program of research, testing, and development of methods for sampling, measurement, monitoring, ~ ~ ~ ~ of air pollutants. Such program shall include . . . analysis, and modeling . . . ~ . . conslderatlon ot 1nc ~1

64 ROTH, ZIMAN, AND FINE vidual, as well as complex mixtures of air pollutants and their chemical transformations in the atmosphere . . . and interactions of ozone with other pollutants." Here, recognition of the need and the appropriateness is ex- pressed in a research prescription. The findings of the research will obvi- ously be applied only over the longer term. The potential for formally examining interrelationships has existed for some time. Knowledge gained from the study of individual groupings of pollutants is certainly applicable. Recognition of the desirability of exam- ining the complex interrelationships among pollutants is reflected in the formation of the Consortium for Advanced Modeling of Regional Air Qual- ity (CAMRAQ) (Hansen et al., 1992~. This group consists of public agen- cies and associations representing research interests of the private sector. The CAMRAQ was formed in 1991 at the suggestion of the Electric Power Research Institute (EPRI). It subscribes to the following principles: · Air pollution occurs over a range of spatial scales, and its study should reflect this attribute. · Air pollutants are linked chemically in the atmosphere, and the study and representation of their reactions should be appropriately comprehen- sive. · The problems are the concern of virtually all public agencies and private sector interests with operations that emit substantial amounts of air pollutants. · A consortium may prove to be a convenient means for establishing research needs and funding the requisite efforts. · Large-scale modeling using high-speed advanced computing tech- niques will be essential to this pursuit. The EPA is an active member of CAMRAQ; it has also recently initi- ated its own program of advanced, interlinked modeling. Because both the CAMRAQ and EPA programs are in their formative phase, it is difficult to anticipate the full nature of the programs to be carried out, the relevant levels of effort, or the schedules for developing products and findings. Spatial Scales Pollutant processes at the regional and urban scales can be highly inter- active: emissions and air quality in surrounding regions can contribute sig- nificantly to ozone formation in urban areas, and ozone formed in urban areas can contribute significantly to regional ambient ozone concentrations. Accounting for the transport of ozone and its precursors to downwind nonattainment areas is a problem that plagues the development of strategies - .,,

TROPOSPHERIC OZONE 65 for attainment. Field studies carried out in the late 1970s and the early 1980s identified transport as a significant issue for a number of nonattainment areas; however, only recently has it been addressed in amendments to the Clean Air Act. In this section, we briefly review the understanding of ozone transport and discuss the extent to which legislation, regulation, and guidance have addressed the issue. Two "transport-related" questions are central to developing effective regional ozone strategies: · At what spatial scales is effective planning for pursuing attainment of the ozone standard best achieved? For larger and more heterogeneous regions, should spatial variability in emissions control requirements be introduced? If so, under what circum- stances? . Before the early 1970s, little, if any, attention was given to establishing the potential role of transport in ozone formation. Since 1974, measure- ment programs carried out in the Midwest, the East, and California have identified urban plumes and regional (ozone) background of anthropogenic origin as contributing significant amounts of ozone and precursors (mainly aged hydrocarbons) to downwind urban nonattainment areas under "favor- able" meteorological conditions. In the aggregate, these studies character- ized conditions conducive to transport and monitored concentrations of trans- ported pollutants at ground level and aloft. The Midwest Interstate Sulfur Transformation and Transport Study (MISTT), conducted in the mid-1970s, was among the first studies to iden- tify transport as an issue (White et al., 1976~. Investigators determined that ozone was formed in the pollutant plume originating in St. Louis. They were able to map its size and shape and estimate its distance of transport. In 1979 the Northeast Regional Oxidant Study I (NERDS I) a field study in which aircraft were used to carry out measurements demonstrated the transport of ozone from Ohio to the East Coast (Clark and Ching, 1983~. In addition although they were primarily aimed at acidic deposition, field mea- surement and air quality modeling efforts that were a part of the National Acid Precipitation Assessment Program (NAPAP) identified ozone transport paths and the meteorological conditions associated with pollutant transport in the eastern United States (NAPAP, 1991~. In California, studies designed to document transport included tracer and aircraft measurements between the Sacramento River Delta and the San Joaquin Valley ~ 1976), within the San Joaquin Valley ~ 1979, 1984, 1990), and between the San Francisco Bay Area and the valley (1990~. The 1974 Aerosol Characterization Experiment (ACHEX) and 1981 Southeast Desert Air Basin Study (SEDAB) provided evidence of transport from the Los Angeles Basin to the southeast desert area. Two studies documented trans ,

66 ROTH, ZIMAN, AND FINE port between Los Angeles and Ventura (1983) and Los Angeles and Santa Barbara (1985), and identified associated meteorological conditions. By the mid-1980s, regional transport was broadly recognized as a principal contribu- tor to nonattainment of the ozone standard in many parts of the country. As noted, the Clean Air Act amendments adopted through 1970 did not specifically address transport nor did they give much attention to nonattainment planning. With the passage of the 1977 amendments, two changes occurred. First, the act recognized transport. However, emphasis was given to emis- sions from individual sources located in attainment areas and their impacts on air quality in nonattainment areas located across state boundaries ESec- tions llO(a)~2~(E) and 1261. Second, the act specifically defined the re- quirements for the state implementation plan for ozone by adding Part D to Title I, which addresses stationary source permit and planning issues. Still, neither the act nor subsequent regulations required that planning specifi- cally account for transported pollutants. In fact, guidance through the 1980s generally led states and local districts to select ozone episodes involving minimum transport for modeling and planning purposes. Thus, agencies tended to restrict planning to examining local impacts of local emissions (personal communication with A. Ranzieri, 1992; personal communication with R. Scheffe, 1992~. An approaching December 1987 deadline for ozone attainment led the EPA, concerned with future SIP efforts, to address issues associated with transport and more extended spatial scales. The agency released a docu- ment entitled, "Post-1987 Planning Guidance" (FR, Vol. 52, November 25, 1987), which extended earlier guidance to include knowledge gained from the review of the latest planning efforts. The document recommended that planning studies using photochemical models take into account sources that were up to 25 miles upwind of a CMSA. Emissions from sources farther upwind were to be reflected in pollutant concentrations at the upwind boundary. However, no specific requirements for control of emissions from these up- wind sources were developed apart from those needed to attain and main- tain the ozone standard locally because no regulations had ever been issued to support Sections 110 (a)~21(E) and 126. Two significant technical impediments forestalled development of the information needed to formulate regulations. First, the EKMA (the model recommended by EPA for use in SIP development) had a number of short- comings that seriously limited its applicability to assessing control strategy options. Although the model contained a sophisticated chemical mecha- nism, its treatment of meteorology was overly simplified. Transport from upwind areas could not be adequately characterized. Moreover, as a result of the assumptions on which it was based, the model was not appropriate for simulating multiday episodes, which precluded using it to assess trans- port at distances greater than that covered in a travel time of about 10 hours .. . i.

TROPOSPHERIC OZONE 67 between the initial location of an upwind air parcel and downwind areas of interest. Second, there was, and continues to be, a paucity of data on air quality, meteorology, and emissions needed to operate and evaluate the EKMA (as well as more sophisticated urban scale photochemical grid models such as the Urban Airshed Model). The 1990 amendments recognized concerns about transport of ozone and its precursors between urban areas in a region by adding two new sections to the act. Section 176A establishes authority for states or the EPA administrator to form interstate transport commissions empowered to rec- ommend regional approaches to mitigating interstate pollution. As noted earlier, Section 184 specifically addresses control of interstate ozone air pollution and mandates a Northeast transport region consisting of 11 states from Maryland to Maine and the District of Columbia, with the subsequent addition of Virginia. However, none of the mandated requirements in Sec- tion 184 addresses the larger issue of regional planning. Although little technical guidance has been offered in accounting for transport in planning, only limited experience exists upon which to base such guidance. The EPA "Guideline for Regulatory Application of the Urban Airshed Model" (EPA, 1991) supports the necessity of modelling episodes associated with upwind transport as well as episodes that are pre- dominately locally generated. Issues associated with geographical scale are recognized, and the EPA recommends that the spatial extent of an upwind region be set "as large as feasible . . . to reduce the dependence of predic- tions on uncertain boundary concentrations and to provide flexibility in simulating different meteorological episodes." Even so, the agency recog- nizes that, as a practical matter, there may not be enough data to extend the upwind boundary sufficiently. Thus, the agency further recommends that states use its regional oxidant model, a coarse-scale, first-generation re- gional model, to provide upwind boundary concentrations for urban-scale modeling. Nowhere in either this guideline or other EPA documents are there specific recommendations for evaluating the merits of uniform versus spatially variable emissions controls. The 1988 California Clean Air Act specifically recognized the need to assess the impacts of transport from upwind areas in planning and to mini- mize its impacts over the longer term. Both the act and subsequent regula- tions require that upwind nonattainment areas develop control strategies that will attain the state and federal ozone standards and also mitigate (to the extent possible) transport to a nonattainment area located downwind. Control requirements are established for upwind areas; they specify the levels of reductions in VOC and NOx emissions and the percentage of sources that must be controlled. However, an alternative set of controls that is equally or more effective, as demonstrated by modeling, is allowed. Down- wind areas are required to provide the reductions needed to mitigate the

68 ROTH, ZIMAN, AND FINE exceedance of the standards that would occur if there were no transport (California Clean Air Act, AB 2595, Chapter 1568, Statute of 1988~. How- ever, similar to the national situation, specific technical guidance has yet to be developed for carrying out the analyses needed to meet these mandates. As indicated, the EPA has been slow to develop regulations or guidance for addressing pollutant transport issues associated with ozone. In large part, this has been because there are no specific data suitable for air quality modeling and analysis of long-range transport, activities that would provide the means for determining the appropriateness of alternative action plans. The language of the 1990 amendments does not mandate that the EPA de- velop a plan encompassing transport issues. Rather, the states comprising an ozone transport commission are empowered to do so, following EPA- issued guidance. These plans are subject to approval by the EPA. At this time it is quite difficult, unfortunately, to address substantively the two questions posed at the outset. Current knowledge is inadequate. During the 1980s, either the long-term funding needed to support acquisi- tion of data and improvement of models was unavailable, or the proposed studies were judged to be of insufficient priority to receive the necessary financial support. Currently, three comprehensive monitoring and modeling studies focusing on ozone are in progress one in central California, en- compassing the region from the San Francisco Bay Area to the southern end of the San Joaquin Valley, the second in the area encircling southern Lake Michigan, and the third in the southeastern United States. The first two studies were specifically designed to provide data bases to support source- oriented photochemical modeling and will be using a second-generation regional ozone model to evaluate alternative potential control strategies. The findings of these studies should provide valuable information for plan- ning regional ozone attainment strategies. The basic issues facing policymakers today who are concerned with air quality planning on a regional scale include determining: · If a mixed or hybrid strategy" for example, VOC control in the ur- ban area and NOX control in the surrounding rural areas is likely to be preferred over more traditional uniform strategies, . areas' . The levels of emissions reductions needed in the urban and rural The amount of transport to downwind urban centers that is likely to occur under emissions control, · The impact of that transport on downwind metropolitan areas, and · The actions that should be taken to mitigate adverse effects in air quality in downwind areas. Efforts are needed to develop procedures for strategic planning at the regional level. For example, one might elect to evaluate control measures . ~

TROPOSPHERIC OZONE 69 sequentially, starting with the specification of measures for attaining the standard in the nonattainment area farthest upwind. Efforts to determine a preferred strategy for the area immediately downwind would then take into account concentrations of "imported" ozone and precursors. We advocate developing both the needed modeling and strategic planning capabilities as soon as practicable. Motor Vehicles: Inspection and Maintenance Are motor vehicle emissions being effectively reduced through fleet emissions reductions and inspection and maintenance (I/M) procedures? Four general approaches have historically been taken, or are being con- sidered, to reduce automotive emissions: (1) technological improvements and modifications to motor vehicles to meet tighter tailpipe and evaporative emission standards and requirements for in-use compliance with the stan- dards; (2) vehicle inspection and maintenance programs; (3) use of reformu- lated gasolines or other fuels that either reduce emissions of pollutants or are less reactive in the atmosphere; and (4) transportation control measures. In this section, we review the legislative and regulatory history of the first two approaches, with emphasis on the passenger vehicle. We highlight some of the issues that have been associated with these approaches. Transportation control measures are discussed in a later section. We will not examine the third approach because the requirement for reformu- lated gasoline has only recently been introduced, and it is premature to examine the issue in this paper. Technological Improvements and Modifications to the Motor Vehicle Congress, in amending the Clean Air Act in 1970, established emission standards that required a 90 percent reduction of hydrocarbons, CO, and NOX from the base year of 1970 for light duty vehicles (1971 for NOX). The standards for CO and VOCs were to be met by 1975 and for NOX by 1976. Although regulators may have held opinions concerning the means for achieving the specified reductions, the legislation and subsequent regulations avoided prescribing a methodology. Rather, required targets for emissions reduc- tions were set, in effect forcing technological development. However, this development required more time than was allotted in the initial legislation. In August 1972 automakers petitioned the EPA for a one-year waiver, indi- cating that development of a catalytic converter required more time (Quarles, 19761. The EPA denied the petition, and the automakers filed for judicial review of the decision. An appeals court overturned the EPA's ruling, and additional hearings were held. In April 1973 the EPA granted a one-year delay based on the testimony at the hearings, but at the same time it tight -

70 ROTH, ZIMAN, AND FINE ened emissions requirements. Delays were granted two additional times through 1975 for a variety of reasons. Congress, through the 1977 Clean Air Act Amendments, extended the implementation dates in a two-step pro- cess to 1981; the standards put in place at that time will remain operative until the 1990 Clean Air Act Amendments are implemented in the mid- l990s. The present standards, given in grams (g) per mile, are 0.41 for hydrocarbons, 3.4 for carbon monoxide, and 1.0 for NOX, based on federal fleet certification procedures. Consistent with a philosophy of forcing technology through performance standards, California adopted a program in 1990 that requires the develop- ment of transitional low emission vehicles (TLEVs), LEVs, ultra-LEVs and Z(ero)EVs over the next seven years (CARD, 1990~. The specified emis- sion limits for nonmethane organic gases (a subset of hydrocarbons) are 0.125 g/mile for TLEVs ~ 1994), 0.075 g/mile for LEVs ~ 1997), 0.04 g/mile for ULEVs (1997), and 0 g/mile for ZEVs (1998~. The performance re- quirements of this program surpass that of 0.25 g/mile specified in the 1990 federal amendments adopted later in the year. To date, vehicle manufacturers have demonstrated that some of their late models will meet the TLEV standards, and a few TLEVs have been certified. To meet LEV requirements, manufacturers are considering differ- ent technologies, such as electrically heated catalysts to reduce cold-start emissions (which are currently the largest source of emissions in the federal test procedure tFTP]), closed coupled catalysts, enhanced catalyst perfor- mance, and improved fuel injection. However, the combination of tech- nologies that will be used for the LEVs and ULEVs has not been deter- mined. Furthermore, the actual deterioration rates associated with these new technologies are unknown. Reliable estimates of the extent to which this program will satisfy stipulated targets (emissions limits) and constraints (schedule and costs) cannot be provided now. Vehicle Inspection and Maintenance Programs Congress recognized in 1977 that some ozone nonattainment areas might not achieve the standard by the December 1982 deadline, even though all requirements and emission reductions specified in Title I, Part D, dealing with planning and stationary source permits, had been implemented. Part D provided for an extension of the attainment date to December 1987, but, in addition, it required in Section 172(b)~11) that the states "establish a spe- cific schedule for implementation of a vehicle inspection and maintenance program." Inspection and maintenance (I/M) programs today vary from state to state, but their purpose is to reduce in-use vehicle emissions through identi- fication and repair of vehicles with high levels of emissions. They typically .

TROPOSPHERIC OZONE 71 consist of an annual or biennial inspection and measurement of tailpipe emissions at two different engine speeds with no load on the engine. If a vehicle fails the test, it must be repaired and retested before it can be registered. The EPA established specific guidelines for the program and provided estimates of emission reductions that could be taken as part of the SIP reasonable further progress (REP) requirements. These estimates were calculated using the EPA mobile source emissions factor program, MOBILE (or the California equivalent, EMFAC). States that implemented I/M were allowed to take credit in their SIPs for a 25 percent reduction of tailpipe emissions from mobile sources. The EPA-mandated I/M program was based on two operating programs that had been conducted by the city of Portland, Oregon, and the state of New Jersey during the mid-to-late 1970s. By the mid-1980s, numerous states had adopted some form of the I/M program and had begun taking credit for the reductions. Unfortunately, as pointed out by McConnell and Harrington (1992) in their recent study of the cost-effectiveness of enhanced I/M, the program is not achieving its goal. Simply having a program in place was sufficient for getting the credit for the 25% reduction toward the state's SIP. There were few requirements for enforcement, including no specific checks for tampering. Nor was there any requirement: to link I/M credits to enforcement or to actual in-use vehicle emissions (McConnell and Harrington, 1992, p. 51. Part of the problem lies in the difference between the EPA's design for the program and its practical implementation. The EPA developed the I/M in a laboratory setting. The pass/fail thresholds were chosen on the basis of iterative analyses such that vehicles that passed the laboratory tests should not fail FTP certification. The EPA engineers identified the causes of fail- ure in the test vehicles, made repairs, and retested the vehicles, including operating them over the FTP cycle. Thus, the EPA developed an idealized laboratory I/M program that produced the expected benefits. However, when this program was implemented nationwide, vehicles did not undergo evalua- tions as intensive as those performed by the EPA. Both this "transference problem" and a failure of the programs to discourage tampering apparently account for the shortfall in emissions reductions. The present two-pronged automotive emissions reduction program (1) catalytic conversion of emissions, coupled with precise electronic control of the air-fuel mixture, and (2) post-1982 implementation of I/M was opera- tive by the mid-1980s. In principle, each part complements the other. The certification standards cover fleet emissions reductions, and the I/M pro- gram is intended to capture those vehicles whose emissions performance has degraded through age, neglect in maintenance, or tampering with the control system. _ ,

72 ROTH, ZIMAN, AND FINE During the past few years, the CARB and the EPA have carried out a number of studies that have~analyzed the effectiveness of California's Smog Check Program and examined automobile emissions under actual operating conditions. Among the states, California has taken the lead in assessment; we thus focus on conclusions drawn from CARB-sponsored studies. Initial and subsequent legislation for the California I/M program re- quired evaluations of the effectiveness of the program. These evaluations were carried out by CARB through covert vehicle emissions testing pro- grams in which vehicles identified as high emitters were taken to I/M test- ing stations to determine if they passed or failed. The vehicles were then inspected by the CARB's automotive testing lab to ascertain if repairs made by the stations were appropriate. In 1986, 800 vehicles were evaluated, in 1989, 1,100 vehicles. The results of the more recent evaluation program have established that, taking into account deterioration effects and the re- sidual benefits of previous inspection cycles, the Smog Check Program has reduced hydrocarbon emissions 19.6 percent and carbon dioxide emissions 15.3 percent (California I/M Review Committee, 1992~. These reductions are less than anticipated for the I/M program and less than those required by state law. While the I/M evaluation studies provided information on the actual effectiveness of the program, other studies analyzed measurements made under actual operating conditions. In one study (Pierson et al., 1990), follow-up analyses compared measurements made in the previously cited Van Nuys tunnel study with vehicle emissions data. It found that the mea surements gave higher CO and HC emission-rates values than expected on the basis of [estimates of an] automotive-emissions model by factors of approxi- mately 3 and 4, respectively (Pierson et al., 1990, p. 1485~. Pierson et al. offered the following observations in their recommenda- tions: Accordingly, it becomes important to verify that this [large discrepancy] is so and to understand why-whether air/fuel ratios are richer in on-road operations than has been thought, whether evaporative emissions have been incompletely accounted for, whether tampering and/or maintenance is worse than assumed, and so forth (p. 1495~. On the basis of the analyses of the Smog Check Program, the CARB has concluded that the present I/M program estimates of actual tailpipe reductions are too high, and that evaporative emissions are not being taken into account. Calculations made using the revised CARB mobile source emissions estimation model, EMFAC-7EP, suggest that emissions reduc- tions of 18 percent for CO and hydrocarbons will provide appropriate cred- its for the present I/M program. -

TROPOSPHERIC OZONE 73 The 1990 Clean Air Act Amendments required that states enact an en- hanced I/M program for areas which are classified as serious or worse under the ozone nonattainment designation requirements. The program is to also include a performance standard achievable by a program combining emission test ing, including on-road emission testing, with inspection to detect tamper ing with emission control devices and misfueling. In July 1992, the EPA proposed an enhanced I/M program (FR, Vol. 57, July 13, 1992) that will require a dynamometer test, with the vehicle com- pleting the first 240 seconds of the hot start FTP cycle under varying engine loads. The program will also be capable of testing for NOX as well as hydrocarbons and CO. The proposed rule was finalized in November 1992. One very important part of this new program, which is missing from the present I/M program, is the ability to detect failure of the evaporative emis- sions control system. Evaporative emissions have been identified by both EPA and CARB as a significant portion of the overall mobile source emis- sions inventory, but these emissions were properly taken into account only in the most recent versions of EPA's MOBILE emissions model. The EPA estimates that the enhanced I/M program will provide significantly greater emission reductions (28 percent for hydrocarbons, 30 percent for CO, and 9 percent for NOX) than the present program. California has taken the lead among the states in examining vehicle emissions. As noted above, California legislation established the I/M Re- view Committee. Part of the legislation required this committee to include recommendations in its 1992 report to the legislature on "the most effective means of reducing tampering and emissions control equipment failures which result in high-emitting vehicles." This legislative mandate was motivated by several recent CARB studies that concluded that approximately 10 to 20 percent of vehicles produce between 40 and 50 percent of total vehicular emissions. The California I/M Review Committee report has identified several different options that may be available in the near future to identify these high-emitting vehicles so that they may be repaired. Each of these options requires some technologi- cal development and costs and effectiveness will need to be analyzed before any one is considered for implementation. The potential options are: (1) use of remote sensing to detect high tailpipe emissions, followed by testing of the vehicle, (2) random roadside surveys in which a small percentage of vehicles would be tested, and (3) on-board diagnostic systems that could detect tampering through a radio transponder implanted in the system. In summary, both the 1977 mandated emissions control technology and the I/M program have provided for significant reductions in vehicular emis -

74 ROTH, ZIMAN, AND FINE signs. The 1990 Clean Air Act Amendments will continue to mandate improvements in each program as a means to further decrease automotive . . emissions. Motor Vehicles: Reducing Use · To what extent should measures that directly or indirectly limit ve- hicle use be considered in formulating regulations for reducing ambient ozone concentrations? During the past two decades, the public's consciousness of the adverse impacts of urban growth has increased in proportion to the diminution in quality of life, on a day-to-day basis, that the public confronts. Road con- struction has promoted suburban sprawl. Increased suburban populations have resulted in longer commutes, increased roadway congestion, and re- duced average speeds on highways. Air quality is adversely affected as well. While these issues go far beyond air quality concerns, some measures which address these issues, such as transportation control measures (TCMs), have been justified on air quality considerations alone. As we have pointed out, present federal environmental laws tend to focus on specific issues, e.g., reducing the impacts of a particular pollutant by reducing emissions from a category of sources. The framework within which congressional decisions are made is often similarly constrained. More integrated or comprehensive approaches to planning and regulation have occurred only infrequently. An increasing awareness of the limitations of depending on an "issues-oriented" strategy alone to meet objectives has led to the advancement of more encompassing recommendations. These in- clude proposals for restricting land use at the local and regional levels-in effect, promoting limits on growth and development. Proposals focusing on mitigating the adverse effects of air quality asso- ciated with land use include measures for reducing automobile use, either directly through TCMs or indirectly through the review and approval of new construction projects, taking into account anticipated increases in vehicle mileage traveled (VMT) that a given project is expected to induce. Ex- amples of TCMs include increased bridge, tunnel, and highway tolls; man- dated increases in vehicle occupancy; "no drive" days; restrictions on driv- ing and parking in center city; and air quality permits for construction of parking lots. Types of "new construction" projects include industrial facili- ties, shopping centers, and residential developments. The permit process that results in approval or disapproval of a construction project and defines mitigation measures to decrease the anticipated VMT associated with the project is termed indirect source review (ISR). As discussed, in 1971, the EPA published regulations governing prepa _~

TROPOSPHERIC OZONE 75 ration of the first state implementation plans for oxidants (FR, Vol. 36, November 25, 1971~. Reducing automobile tailpipe emissions and control- ling new stationary sources were the principal means for attaining the stan- dard. However, the EPA encouraged states to develop TCMs and consider permits for indirect sources. Among the TCMs that the EPA suggested were the following: measures to reduce vehicle traffic, including but not limited to, measures such as commuter taxes, gasoline rationing, parking restrictions, staggered work hours . . . [and] expansion or promotion of the use of mass transit facilities through measures such as increases in the frequency, convenience, and passenger carrying capacity of mass transportation systems or provid- ing for special bus lanes on major streets and highways (FR 36, 22398, November 25, 1971~. The EPA did not specify the approaches to be taken in controlling emissions resulting from indirect sources, but it did not rule out land use measures. Later in the year, the agency enacted a national program for indirect source review and a Transportation Control Plan (FR, 36, November 25, 19711. The Transportation Control Plan contained the TCMs suggested in the 1971 SIP regulation. The ISR program had the intent of approving or denying a permit for the proposed indirect source on the basis of its air quality impacts. This program gave rise to numerous lawsuits throughout the United States. Although individual legal challenges had different re- sults, the overall outcome established that the EPA lacked the legal author- ity to compel the states to adopt these measures (personal communication with M.R. Barr, 1992~. The EPA withdrew the ISR program in 1975 as a result of congressional action (FR, 40, 129, July 3, 1975~. In 1974 Congress made minor amendments to the Clean Air Act in the Energy Supply and Environmental Coordination Act. This act specifically prohibited the EPA from promulgating or requiring the states to promulgate an indirect source review program and left the program to the discretion of the states. Further, Congress redefined TCMs in light of the earlier prob- lems associated with the EPA's Transportation Control Plan by removing the authority to require implementation and leaving adoption and implementa- tion to the discretion of the state. Examples of TCMs specifically cited in Section 108(f)~1~(A) of the 1977 amendments are the following: programs to improve public transit, programs to establish exclusive bus and car pool lanes and area wide car pool programs, programs for long range transit improvements involving new transportation policies and trans- portation facilities or major changes in existing facilities. As a result, although all pre-1992 SIPs retained TCMs, they tended not

76 ROTH, ZIMAN, AND FINE to take credit for the estimated emissions reductions that were to derive from implementing the measures, in part because of the voluntary nature of the program and in part because of the difficulty in estimating the likely air quality improvements. Even though attempts to decrease VMT through the use of TCMs were unsuccessful, the question remains as to whether emis- sions reductions related to TCM and land use are significant. In recent years, Congress has attempted to enact more stringent legisla- tion involving TCMs. The TCM-related provisions of the 1990 amendments aim to reduce emissions by requiring that ozone nonattainment areas classi- fied as severe and extreme develop plans to offset growth in emissions due to VMT. As interpreted by the EPA, changes in the fleet composition and other measures that reduce tailpipe emissions can be credited toward main- taining total vehicle emissions at a constant level. The plans, which were to be submitted as part of the November 1992 SIP revisions, were to empha- size transportation control measures that are identified in Section 108(f)~1) of the amended act. These measures include such programs as improved public transit, high occupancy vehicle lanes, trip reduction ordinances, re- striction of vehicles in downtown areas during peak hours, and employer- based transportation management plans. Many of these programs require enabling legislation at local, regional, and state levels. In addition, the 1992 SIP revisions must contain compliance plans for each employer of 100 or more persons to increase average passenger occupancy of vehicles in which employees commute between home and work by 125 percent by November 1996. Few states have tried to quantify emissions reductions that will result from implementation of the 1990 amendments. However, the 1988 Califor- nia Clean Air Act contains requirements for reducing VMT similar to those of the 1990 amendments. As part of the 1991 Clean Air Plan, the Bay Area Air Quality Management District (BAAQMD) has estimated the benefits of these reductions. They are small, amounting to 10 tons/day (t/d) of hydro- carbons (2 percent of the projected baseline 1997 emissions inventory) and 16 t/d of NOX (2.8 percent of the projected inventory). The district has also adopted additional TCMs, including some measures proposed by the EPA in 1971. These include smog fees, congestion pricing, work parking charges (i.e., institution of the practice in which employers must charge employees for parking privileges at their work place), and gas tax increases; most of these will require additional legislative authority before they can be imple- mented. Even these measures, combined with the previous reductions, are estimated to result in only a 41 t/d decrease in hydrocarbons and a 57 t/d decrease in NOx. The BAAQMD has ranked all of the measures adopted in the 1991 Clean Air Plan in terms of cost-effectiveness. Except for a single measure to expand employer assistance programs (ride sharing), all trans- portation control measures have gross costs of between $25,000 and $1 f

TROPOSPHERIC OZONE 77 million per ton of emissions reduced. These costs are much higher than the majority of those for stationary and area source measures cited in the plan (BAAQMD, 199 1~. The BAAQMD cost estimates raise important questions as to whether TCMs are cost-effective measures for improving air quality. Independent estimates from other districts and states are needed before one can draw general conclusions about the cost-effectiveness of TCMs. That informa- tion should be forthcoming at the time of the 1994 SIP submissions. Never- theless, state and local governments may elect to adopt indirect source mea- sures and TCMs, including those TCMs considered in the past (which, in some cases, have proven to be controversial). Where such actions are con- sidered, it will certainly be appropriate to assess their air quality benefits through quantitative analysis. In summary, policies that support indirect source review and TCMs are more likely to be justified through their contribution to alleviating the local and regional societal concerns that were noted in the beginning of this section rather than through their air quality benefits alone. Other Topics This section summarizes topics of interest that could not be included in the more detailed preceding review. Assessment of Progress Toward Attainment of the Standard The ozone monitoring network in the United States provides an ad- equate, although not fully satisfactory, sampling of ozone concentrations in and immediately downwind of urban areas. Rural monitoring is more sparse, and the network would certainly benefit from bolstering. However, VOC and NOx, the precursors to ozone, are not measured, or are measured spar- ingly, in most urban areas. This paucity of information severely limits the ability to evaluate the effectiveness of emissions control programs. Two reasons appear to account for this deficiency in monitoring. First, the technology available for measuring VOCs and NOx was, until recently, not accurate enough. Moreover, acquisition and accurate analysis of VOC samples are costly; typically, costs are $300 to $500 per sample. (The development of inexpensive, continuous monitors for VOCs is still needed.) Second, the regulatory community appears to have done one of two things: (1) It has accepted the notion that the costs saved by not monitoring precur- sors outweigh the benefits of the additional information, which would be useful in establishing trends, assessing the effectiveness of control pro- grams, and verifying the accuracy of emissions models and inventories. (2) Or, it has overlooked, or been unaware of, the importance of having such

78 ROTH, ZIMAN, AND FINE information. In this case, added information would have promoted the use of science to support the regulatory process. Unfortunately, those scientists who were sensitive to the need for such information for many years were clearly unable to convince federal and state agencies of the importance of conducting the needed monitoring. Retrospective Analyses of State Implementation Plans Historically, few, if any, SIPs have provided accurate estimates of im- provements in air quality related to ozone levels. Virtually all estimates of future air quality have proven to be overly optimistic; actual peak ozone concentrations in retrospect have been higher than those projected. The API, in a 1988 analysis of ozone SIPs, found that 1982 SIPs suffered sev- eral generic deficiencies that caused this problem, including underestima- tion of base year emissions inventories and the resultant underestimation of future year inventories, failure to apply the EKMA model only in conditions in which its assumptions are met, overestimation of effectiveness factors for emissions reduction measures, and inadequate representation of long range transport of pollutants into a region (API, 1989~. The overestimates of effectiveness were the result of delays in developing rules, inaccurate esti- mation of actual "technical" effectiveness, and lack of compensation for shortfalls in emissions reductions (API, 1989~. While SIPs have historically displayed common patterns of inaccuracy, methods of detection and correction have been inadequate or lacking. Criti- cal elements include monitoring designed to detect and quantify progress toward attainment, comparison of progress with SIP projections, identifica- tion of shortfalls in air quality improvement, determination of the causes of shortfalls, specification of corrective steps in control, revision of the SIPs to reflect the needed changes, and implementation of the controls. "Science" has recognized this need; regulation has not. Introduction of "Cleaner" Fuels Title II of the CAAAs of 1990 requires the eventual sale of only refor- mulated gasoline in the nine urban areas having the highest peak ozone concentrations, institutes two clean-fueled vehicle programs, including a pilot program in California, and mandates maximum fuel volatility. While volatility reductions have led to reduced VOC emissions, the impact of introducing "cleaner" fuels is less clear. Today, many argue that the legisla- tion requiring the introduction of clean fuels preceded proper development of the supporting science. Some believe that the long-term benefits are questionable. Whatever the eventual findings, "clean fuels" is a major issue today, one that certainly merits attention and scrutiny. We did not address _ J

TROPOSPHERIC OZONE 79 the topic in this paper because of its relative novelty and thus lack of history, the extreme sensitivity of the issue, and the extensive coverage that the topic would necessarily have to receive. However, the clean fuel and reactivity issues are of at least the same interest and timeliness as most of the topics addressed earlier. THE INTERPLAY OF REGULATION AND SCIENCE AND TECHNOLOGY DEVELOPMENT Scientific and technological advances and legislative and regulatory history are intimately intertwined in our earlier discussion. We now exam- ine the interplay among them and develop some general observations about the influence of each on the other. Figure 3 provides a timeline of key events. The Response of the Regulatory System to New Scientific Understanding A general observation emerging from this inquiry is that the regulatory system has often responded to new scientific understanding of tropospheric ozone either with inertia or only after considerable delay. At times, there have been good reasons for the lag time. Steps in the process can be characterized as follows: Advances in knowledge develop gradually over time. As knowledge accumulates, existing views or positions become sub- ject to challenge, the vigor of which increases in proportion to the growing evidence. . Uncertainties persist, making it difficult to characterize adequately weaknesses or flaws in current and, sometimes, prior positions. · Interests on each side of an emerging or persistent issue tend to represent their positions in committees or public forums by emphasizing the pros and minimizing the cons, which often results in polarization. · Because of the inability to establish an incontrovertible position, debate continues for some time, leading to delay. traduced. · Eventually, the new position or view holds sway, and change is in Although the time period associated with this process is variable, it seems to range from 5 to 15 years. Earlier we discussed issues that exemplify this pattern: · Revisiting specification of the ambient standard for ozone. The Clean Air Act provides for review of the ozone standard at five-year intervals.

80 Science and Engineering Development of Appendix J curve Emphasis on VOC control Formulation of chemical mechanisms Recognition of NOX inhibition 2-way catalytic converter EKMA modeling and diagram Recognition of regional transport Establishment of first state vehicle inspection and maintenance (I/M) programs -Application of urban airshed modeling (UAM) 3-way catalytic converter Vehicle l/M programs for post-1992 required for nonattainment areas Initiation of major monitoring/modeling programs in California Recognition of potential benefits of NOX controls in areas of high biogenic emissions and in rural areas OTA issues report on steps for reducing urban ozone Initiation of major monitoring/modeling programs nationwide Advent of regional ozone modeling Underestimates of vehicle VOC emissions recognized _ I_ 1 - NRC issues report on tropospheric ozone formation and measurement - Publication of cost-benefit analyses ROTH, ZIMAN, AND FINE Policy and Regulation 1 970 1 175 . ~. 1 91 0 19t5 1990 - - Clean Air Act Amendments of 1990 - UAM regulatory guidelines for SlPs - Regional transport determination guidance - Stationary source NOX guidance - Clean Air Act Amendments of 1970 - Oxidant standard (0.08 ppm) - Transportation control measure plan (TOM) regulation - Indirect source control plan (ISC) regulation - SIPs regulation - Federal ISC authority transferred to states - Federal TOM (discretionary) Clean Air Act Amendments of 1977 - Ozone standard revised to 0.12 ppm - SIP, NSR regulations revised - Vehicle emission standard guidance · Post-1987 attainment guidance proposed for Sips, including NOX reductions if necessary and use of UAM FIGURE 3 Timeline of significant scientific and technical, legislative, and regula- tory events for ozone control. ,.,

TROPOSPHERIC OZONE 81 The EPA announced in August 1992 that it will not alter the ozone standard at this time, stating that it did not have enough time to compile information describing relevant study efforts and complete its formal review. This an- nouncement came seven years after the 1985 statutory deadline for review. Although the CASAC had been divided on the need for imposing a more stringent standard when it last met in 1988, Morton Lippmann, who chairs the EPA Advisory Committee on Indoor Air Quality and Total Human Exposure, stated that "new published data since 1988 was available and could have been reviewed in time. They (EPA) recognized if they incorpo- rated the current data, they would no longer be capable of defending the current standard." Bernard Goldstein, director of the Environmental and Health Services Institute at Rutgers University, added that "the additional data that has come out would certainly lean toward making things more stringent" (Weisskopf, 1992~. Apparently, both Dr. Goldstein and Dr. Lippmann believe that health-related evidence supports a more stringent standard. In response, Robert Brenner, head of the EPA's Air Policy Office, said that "our focus has been getting controls in place. Putting in new standards doesn't mean you improve the air. It's the regulations we're issuing under the Clean Air Act that will improve air quality." · Emphasizing reduction in emissions of both precursors to ozone. The EPA's long-standing policy favoring VOC control and Reemphasizing or disregarding NOX control, though challenged at various times, remained essentially unaltered from the early 1970s to the late 1980s. Uncertainty clearly prevailed during this period, but even as evidence mounted suggest- ing the benefits of NOX control in at least some areas of the United States, the agency was essentially unresponsive until very recently. · Recognizing the relationships of ozone precursors to pollutants other than ozone. Even though a number of studies from large-scale field pro- grams to detailed modeling efforts have demonstrated the interactions among air pollutants, the perceived complexity of undertaking comprehensive analyses contributed to inadequate attention being given to the issue. Also, issues can usually be addressed and managed more easily when they are compart- mentalized than when they are integrated. The EPA's apparent avoidance of forging integrated pollutant programs may thus derive from practical, albeit untested, concerns. · Specifying the spatial scale for planning emissions reductions. Long- range transport of precursors and secondary pollutants has been recognized clearly for many years. The primary reason for delay in undertaking assess- ments and planning at the appropriate spatial scales appears to have been political; planning is carried out by designated agencies whose authority is constrained in geographical extent. A significant will is required to effect change; jurisdictions are often unwilling to relinquish authority even if the cause is well intended. 4

82 ROTH, ZIMAN, AND FINE · Conducting ambient monitoring of precursors to assess and diag- nose problems. Monitoring of ozone concentrations has been supported by regulatory agencies for many years. However, much less attention has been given to the routine measurement of NOX and VOC concentrations. The paucity of these data has limited the scientific and regulatory communities' ability to determine the effectiveness of emissions reduction programs, the accuracy of emissions representations, and the geographical extent of NOX . . . limitation. . Conducting large-scale integrated modeling and monitoring programs. While it was well known that it was necessary to acquire comprehensive aerometric data bases to properly support urban-scale and regional model- ing, serious commitments of funds to this pursuit were made only in the mid-1980s and subsequently. Before that time, only limited data bases, often compiled using routine monitoring data, were available for use as inputs to air quality models and in evaluating model performance. Thus, the accuracy and precision of modeling estimates were limited by the pau- city of data and not by the formulation of the model. This limitation per- sists today, as the programs launched five to eight years ago are only now reaching fruition; evaluations of model performance using the data bases acquired are just now being conducted. Even today, virtually no regional- scale data bases exist. · Characterizing and quantifying the role of natural emissions in ozone formation. As was discussed earlier, for much of the 1980s EPA's attention was diverted from the study of biogenic emissions in the belief that they were not a significant contributor to ozone formation. Although this view was disputed by some members of the scientific community, progress in this field was effectively limited by the paucity of funding for research to de- velop methods for sampling and analyzing naturally emitted and highly reactive VOCs, determine the rates of emissions from biota, and estimate total biomass for different species. In some cases, the delay in acting on new information has been attribut- able to Congress; 13 years elapsed between 1977 and 1990, the year in which the most recent amendments were enacted. Congressional discussion and debate seemed interminable to many. The need to resolve failures to meet attainment deadlines and to empower the EPA to reestablish the SIP process apparently provided the inducement for resolving the deadlock. To be sure, the implications of acting on several of the key issues were quite significant costs of the programs; impacts on various cohorts of the popu- lation, including jobs; uncertain consequences of introducing new programs, such as emissions trading; and the inevitable dilemma of resolving differ- ences among competing interests. Nevertheless, the process of enacting legislation seems unnecessarily inefficient and prone to favor political over scientific considerations. .

TROPOSPHERIC OZONE 83 In other cases, the EPA has appeared slow to respond to the develop- ment of new information. As discussed, the VOC versus NOX debate has been going on for well over a decade. However, evidence began to build in 1985 that some regions of the country were very likely ''NOx-limited.'' Guidance emerging from the agency in the late 1980s represented a gradual shift in policy, suggesting that NOX control might be warranted in some circum- stances. However, in post-1987 SIP analyses, the need for NOX control had to be demonstrated prior to its acceptance as part of a control strategy. In effect, NOX was "innocent until proven guilty." This position clearly changed with the 1990 amendments; NOX control is required in areas classified as serious, severe, or extreme unless it can be demonstrated that NOX reduc- tions do not result in ambient ozone benefits. Now, NOX is presumed "guilty until proven innocent." This transition in position took about five years to effect. More recently, in December 1991, the NRC Committee on Tropo- spheric Ozone Formation and Measurement stated that ''NOX control is nec- essary for effective reduction of ozone in many areas of the United States" (NRC, 1991, p. 111. As a result, the EPA and other agencies are giving intensive attention to evaluating the merits of NOX emissions reductions. Similar "case histories" can be outlined for the need to (1) assess the influences of ozone precursors on other regulated pollutants, rather than consider the ozone-NOx-VOC system in isolation, and (2) examine emis- sions control requirements on a sufficiently broad spatial scale to include all significant source and receptor areas. In both instances, recognition devel- oped in the late 1970s to early 1980s and evidence of the need increased in the years following. Still, in the former case, no guidance for comprehen- sive "interactive" assessment is forthcoming. In the latter case, regional studies are now being undertaken in some areas southern Lake Michigan, central California, and the Southeast. However, a number of geographical areas for which implementation plans are to be prepared are still circum- scribed by geopolitical boundaries that do not encompass critical source areas. Consequently, the impacts of and responses to longer range transport of pollutants cannot be effectively addressed in these areas. Note that the EPA has yet to provide guidance on methods for developing control strate- gies in regions where transport is an issue. Such guidance should address the matter of uniform versus nonuniform strategies, that is, applying the same control strategy throughout the region or varying strategies from one major source area to another within the region. Finally, some of the apparent delay in response derives from a discom- fort with acting, or an unwillingness to act, in light of uncertainty. "Exces- sive uncertainty," in turn, may be a consequence of governmental research programs not being sufficiently long term and consistently focused to pro- vide the information needed to reduce uncertainties to acceptable levels. If true, this supposition suggests the need for a critical assessment of proce

84 ROTH, ZIMAN, AND FINE cures for identifying research needs, establishing priorities, committing to the long term, and providing sufficient funding to ensure success. Incentives and Disincentives in the Regulatory System The primary incentive to seek new information overlaps with the pri- mary disincentive. On the one hand, true knowledge provides the only meaningful basis for actions that circumstances appear to demand. On the other hand, most relevant research requires money and time, often in the range of 5 to 10 years or more. Where circumstances require action, such as smog conditions in the South Coast Air Basin, the waiting time for research results exceeds the time practically available for taking the actions. Resolution of this dilemma is exceedingly difficult. One option is to design actions that can be carried out in sequence, instituting more stringent con- trols with time, as needs warrant. The results of research can then influence the "action sequence" as they become available. In any event, inadequate or sporadic funding, disrupting or weakening an otherwise attractive research program, can prove to be a significant disincentive to pursue the activity and thus to seek new information. Acceptance of New Information by the Regulatory Community Factors contributing to acceptance or lack of acceptance of new infor- mation are complex-part institutional, part psychological, part related to risk averseness, part to commitment to current paradigms. The notion of "acceptance or lack of acceptance" is an oversimplification; often, accep- tance constitutes a slow process of learning and becoming comfortable in effect, a protracted transition. We can only speculate on the factors that are most influential in determining an individual's inclination to use new infor- mation. Factors that contribute to resisting the acceptance of new informa- tion include those listed below: · Doubt as to its reliability or correctness. · Extent to which it conflicts with one's current view of the matter (or the difficulty involved in permitting or accepting the overturning of a cur- rent conception or framework for action). The perception of intent to delay the taking of an action. Averseness to risk, that is, it is often easier to maintain "status quo" than to accept or effect change. · The need to alter or expand jurisdictional responsibility for regula- tion (such as expanding a jurisdiction from intrastate to interstate). · Inadequacy in communication. · Inability to characterize uncertainty. , . . .

TROPOSPHERIC OZONE 85 In situations in which more than one of these factors comes in to play, such as (1) revisiting the ambient standard, (2) determining if NOx control is an appropriate strategy, (3) addressing interpollutant issues, and (4) ad- dressing transport considerations, acceptance of a "new position" may be difficult to effect. One might argue that information sufficient to resolve key technical uncertainties seldom becomes available within the time frame in which policymakers feel compelled to act. While knowledge may be incomplete, the latest available scientific information provides the basis for moving forward, weighing options, and promoting change. However, "an adequate knowledge base" that required to support truly informed deci- sion making- is the pot at the end of the rainbow: while we may try, we never seem to get there. The job of the decision maker is to evaluate contrasting risks: (1) taking action based on "insufficient data" and risking society's incurrence of un- necessary costs if expectations of benefit are misplaced or unduly optimis- tic, and (2) delaying action and thus exposing society to greater ambient concentrations of air pollutants than if controls were imposed. One path to easing the policymakers' burden is to develop estimates or at least clear qualitative statements of the risk associated with each option for action or inaction, and communicate this information clearly to decision makers for their consideration. We advocate that suitable procedures for assessment and communication of risk be developed (where they are not now avail- able), prescribed, and applied as soon as practicable. Governmental Perspectives, Incentives, and Disincentives Regulatory structures at different levels of government may respond differently to a perceived issue or need. It is not possible to characterize the differences accurately or comprehensively because various governmental structures exist in the United States. However, some general observations can be made. · Lower levels of government may find it easier to rely on higher levels of government to develop regulations. Often, issues are controver- sial. Where the "heat is high," it is expedient to point to a requirement placed on a community by "a higher authority" than to enact rulemaking within the community itself. · Most states follow the federal lead. Some act reasonably promptly; others appear to move slowly and reluctantly. In a few instances, a state will assume a lead role or perhaps chart a somewhat independent course. California is notable in this regard. The relationship of local or regional development of regulations to state development of regulations bears a resemblance to that of state regulation and federal regulation. Local agencies generally act in response to direc

86 . ROTH, ZIMAN, AND FINE fives issued at a higher level sometimes promptly, sometimes slowly. In some instances, a local or regional agency will assume a lead role, particu- larly in planning or rulemaking. Notable here and familiar to us are the actions of the South Coast and Bay Area Air Quality Management Districts. · Local perception that a problem is severe and thus in need of atten- tion and a significant level of local support for taking action appear to be requisites for a local or regional agency to assume a leadership role in rulemaking or regulation. Where California has assumed a leadership role, it seems to have encountered fewer barriers to action, acceptance, and implementation than has the federal government. One result is that the period from conception to implementation is much shorter. The reasons for the differences between federal and state processes are not entirely clear. However, Matthew Wald (1992) recently commented on the subject in the New York Times. He noted that the California Air Resources Board "has pretty much had its own way and has been what the E.P.A. would probably like to be: tough, well funded and backed by a strong political consensus for cleaner air.... It regularly exercises a level of authority that Federal regu- lators have largely been without since the beginning of the Reagan years." Note that the CARB has final authority in California; EPA positions are subject to review by the Office of Management and Budget (OMB) and, recently, by the White House Council on Competitiveness. Role of Technology in Shaping Actions of the Regulatory System As indicated by the history of regulation of tropospheric ozone in the United States, regulations generally prompted the development of the tech- nologies required for compliance. The classic example is that of the cata- lytic converter for the automobile, which is generally viewed as a success story. Of course, the fundamental science may already have been developed or many or most components of the technologies may already have been available. Regulation focused attention on a particular need and brought together the components required for developing the desired process or product or capability. (Although regulation promoted the development of suitable control technology, it did not specify a technological approach; rather, it prescribed a performance requirement.) Sometimes science or technology precedes regulation. Grid-based pho- tochemical models were developed during the 1970s; the EPA supported this work to advance understanding and obtain useful simulation capabili- ties. Later, when the models were judged to be sufficiently advanced, were more widely accepted by the regulatory community, and were viewed as useful, requirements for their application were included in regulation spe ~ .

TROPOSPHERIC OZONE 87 cifically, in the 1990 amendments to the Clean Air Act. (However, signifi- cant issues associated with use of the model, which derive from uncertain- ties in formulation of the model and deficiencies in supporting data bases, remain to be resolved.) In this case, science led, and regulation followed. In some instances, notably in determining the health effects and threshold concentrations of pollutants, the regulators have sought assistance and ad- vice, have promoted the need for further scientific advances, and have prod- ded the scientific community to take positions on issues exhibiting signifi- cant uncertainties. In such circumstances, the interaction between regulation and science is complex: the roles of scientist and regulator as leader and respondent are not always clear. A PROPOSAL FOR CONSIDERATION Several parts of the preceding discussion illustrate difficulties in carry- ing out longer-term scientific research within a regulatory agency. Science requires time and continuing financial support. Regulatory needs are often shorter term; they frequently demand redirection of effort and reprogram- ming of funds. Perhaps it would be wise to separate the longer-term pursuit of science from the regulatory structure. One means for accomplishing this is to create a national environmental research center, funded by Congress. Major research initiatives would be undertaken at the center. Moreover, agencies would be permitted to fund longer-term studies conducted at the center at a level of up to one-third of the center's budget. Short-term reseach would be retained within the agen- cies. While we realize that many factors must be considered in evaluating the merits of this proposal, we offer the suggestion to promote thought and stimulate discussion. The interplay between science and regulation merits a much deeper examination than we are able to provide here. The lessons that could be learned, if translated into practice, are likely to justify the effort many times over. ACKNOWLEDGMENTS We sincerely thank John H. Seinfeld and Myron F. Uman for their enthusiastic support and encouragement. We also thank John Bachmann, Michael Barr, Don Blumenthal, Ken Demerjian, Basil Dimitriades, Bob Friedman, Fred Lurmann, Will Ollison, Richard Scheffe, Robert Slott, and Steve Welstand for offering their perspectives on historical events, scientific studies, and regulatory actions. We are also most appreciative of Sandra Golding's edit- ing efforts.

88 ROTH, ZIMAN, AND FINE REFERENCES American Petroleum Institute. 1989. Detailed Analysis of Ozone State Implementation Plans in Seven Areas Selected for Retrospective Evaluation of Reasons for State Implementa- tion Plan Failure. API Publ. No. 4502. Atkinson, R., and A. C. Lloyd. 1984. Evaluation of kinetic and mechanistic data for modeling of photochemical smog. Journal of Physical Chemistry Reference Data 13:315~44. Bay Area Air Quality Management District. 1991. Bay Area '91 Clean Air Plan. (October 30). California Air Resources Board. 1990. Resolution 90-58 - Low-Emission Vehicles/Clean Fuels. (September 28). California I/M Review Committee. 1992. Evaluation of the California Smog Check Program and Recommendations for Program Improvements (Public Draft). (15 October). Chameides, W. L., R. W. Lindsay, J. Richardson, and C. S. Kiang. 1988. The role of biogenic hydrocarbons in urban photochemical smog: Atlanta as a case study. Science 241:1473- 1475. Clark, J. F., and J. K. S. Ching. 1983. Aircraft observations of regional transport of ozone in the Northeastern United States. Atmospheric Environment 17:1703-1712. Delucia, A. J., and W. C. Adams. 1977. Effects of O3 inhalation during exercise on pulmo- nary function and blood biochemistry. Journal of Applied Physics: Respiratory Environ- mental Exercise Physiology 43:75-81. Dimitriades, B. 1972. Effects of hydrocarbon and nitrogen oxides on photochemical smog formation. Environmental Science and Technology 6(3):253. Dimitriades, B. 1977. An Alternative to the Appendix-J Method for Calculating Oxidant- and NO2-related Control Requirements. Proc. Internat. Conf. on Photochemical Oxidant Pol- lution and Its Control, Vol. II. U.S. Environmental Protection Agency. Research Tri- angle Park, N.C. 871. Federal Register. 1971. Title 42 - Public Health. Part 410-National Primary and Secondary Ambient Air Quality Standards. 36(April 30):8186. Federal Register. 1971. Part 51 - Requirements for Preparation, Adoption, and Submission of Implementation Plans. 36(November 25):22398. Federal Register. 1975. Part 52 - Approval and Promulgation of Implementation Plans. Review of Indirect Sources. 40(July 3) no. 109. Federal Register. 1979. Part 50 - National Primary and Secondary Ambient Air Quality Standards. 44(February 8):8202. Federal Register. 1987. State Implementation Plans; Approval of Post-1987 Ozone and Car- bon Monoxide Plan Revisions for Areas Not Attaining the National Ambient Air Quality Standards; Notice. 52(November 24):45044. Federal Register. 1992. Part 51 - Vehicle Inspection and Maintenance Requirements for State Implementation Plans, Proposed Rules. 57(July 13):31058. Fujita, E. M., B. E. Crces, C. L. Bennett, D. R. Lawson, F. W. Lurmann, and H. H. Main. 1992. Comparison of emission inventory and ambient concentration ratios of CO, NMOG, and NOX in California's South Coast Air Basin. Journal of the Air and Waste Manage- ment Association 42(3):264-276. Hackney, J. D. 1975. Experimental studies on human health effects of air pollutants. Archives of Environmental Health 30:373-381. Hall, J. V., A. M. Winer, M. T. Kleinman, F. W. Lurmann, V. Brajer, and S. D. Colome. 1992. Valuing the health benefits of clean air. Science 255:812-816. Hansen, D. A., R. L. Dennis, A. Ebel, S. Hanna, J. Kaye, and R. Thuillier. 1992. CAMRAQ: The Quest For Modern Solutions to Regional Air Quality Problems. (October 20). Harley, R. A., A. G. Russell, G. J. McRae, L. A. McNair, D. A. Winner, M. T. Odman, D. Dabdub, G. R. Cass, and J. H. Seinfeld. 1992. Continued Development of a Photochemi r ~ . _

TROPOSPHERIC OZONE 89 cat Model and Application to the Southern California Air Quality Study (SCAQS) Inten- sive Monitoring Periods: Phase I. Carnegie Mellon University and California Institute of Technology. Final Report to the Coordinating Research Council under project SCAQS-8. Ingalls, M. N., L. R. Smith, and R. E. Kirksey. 1989. Measurement of On-road Vehicle Emissions Factors in the California South Coast Air Basin, Vol. 1: Regulated emissions. SCAQS-1, Final Report. No. SwRI-1604. San Antonio, Texas: Southwest Research Institute. Jeffries, H. E., and R. R. Crouse. 1992. Scientific and Technical Issues Related to the Application of Incremental Reactivity, Part II: Explaining Mechanism Differences. Glen- dale, Calif.: Western States Petroleum Association. Krupnick, A. J., and P. R. Portney. 1991. Controlling urban air pollution: A benefit-cost assessment. Science 252:522-528. Landy, M. K., M. J. Roberts, S. R. Thomas, and V. Nazar. 1990. The Environmental Protection Agency: Asking the Wrong Questions. Chapter 3 in Revising the Ozone Standard (with Valle Nazar). New York: Oxford University Press. Lawson, D. R., P. J. Groblicki, D. H. Stedman, G. A. Bishop, and P. L. Guenther. 1990. Emissions from in-use motor vehicles in Los Angeles: a pilot study of remote sensing and the inspection and maintenance program. Journal of the Air and Waste Management Association 40:1096. Linn, W. 1978. Health effects of exposure in asthmatics. American Review of Respiratory Disease 117:835-841. Lippmann, M. 1989. Health effects of ozone, a critical review. Journal of the Air Pollution Control Association 39(5):676. Lippmann, M. 1991. Health effects of tropospheric ozone. Environmental Science and Technology 25(November 12):1956. Melnick, R. S. 1983. Regulation and the courts: The case of the Clean Air Act. Chapter 8 in Air Quality Standards in the Courts. Washington, D.C.: The Brookings Institution. McConnell, V., and W. Harrington. 1992. Cost-Effectiveness of Enhanced Motor Vehicle Inspection and Maintenance Programs. Discussion Paper QE92-18. Resources For the Future. (April 1992). National Acid Precipitation Assessment Program. Acid Deposition: State of Science and Technology. 1991. Nlol. 1, Emissions, Atmospheric Processes, and Deposition, P. M. Irving ed. Washington, D.C.: Government Printing Office. National Research Council. 1991. Rethinking the Ozone Problem in Urban and Regional Air Pollution. Washington, D.C.: National Academy Press. Office of Technology Assessment, Congress of the United States. 1989. Catching Our Breath: Next Steps for Reducing Urban Ozone. OTA-0-412. Washington, D.C. Pierson, W. R., A. W. Gertler, and R. L. Bradow. 1990. Comparison of the SCAQS tunnel study with other on-road vehicle emission data. Journal of the Air and Waste Manage- ment Association 40:1495. Quarles, J. 1976. Cleaning Up America. Boston: Houghton Mifflin. Reynolds, S. D., P. M. Roth, and J. H. Seinfeld. 1973. Mathematical modeling of photo- chemical air pollution - I: Formulation of the model. Atmospheric Environment 7:1033- 1061. Reynolds, S. D., T. W. Tesche, T. Dye, P. Roberts, D. E. Franzon, L. R. Chinkin, and S. B. Reid. 1992. Assessment of Planned NESCAUM/NOTC Modelin, Activities, Final Re- port. Washington, D.C.: American Petroleum Institute. Schoettlin, C. E., and E. Landau. 1961. Air pollution and asthmatic attacks in the Los Angeles area. Public Health Reports 76:545-548. Trainer, M., E. T. Williams, D. D. Parrish, M. P. Buhr, E. J. Allwine, H. H. Westberg, F. C.

9o ROTH, ZIMAN, AND FINE Fehsenfeld, and S. C. Liu. 1987. Models and observations of the impact of natural hydrocarbons on rural ozone. Nature 329:705-707. U.S. Environmental Protection Agency. 1971. Air Quality Criteria for Nitrogen Oxides. AP- 84, January. Washington, D.C.: Environmental Protection Agency. U.S. Environmental Protection Agency. 1988. Review of the National Ambient Air Quality Standards for Ozone Assessment of Scientific and Technical Information. Washington, D.C.: EPA, Office of Air Quality Planning and Standards. U.S. Environmental Protection Agency. 1989. Review of the NAAQS for Ozone: Closure on the OAQPS Staff Paper (1988) and the Criteria Document Supplement (1988). Report of the Clean Air Scientific Advisory Committee (CASAC). U.S. Environmental Protection Agency. 1991. Guideline for Regulatory Application of the Urban Airshed Model. EPA-450/4-91-013. Washington, D.C.: EPA, Office of Air Qual- ity Planning and Standards. von Nieding, G. 1977. The acute effects of ozone on the pulmonary function of man. VDI Berichte 270:123-129. Wald, M. 1992. California's pied piper of clean air. The New York Times 141(3)(September 13):F1. Wagner, K. K., and N. J. M. Wheeler. 1991. An investigation of modeling emission inventory bias with Urban Airshed Model sensitivity simulations. Presented at Tropospheric Ozone and the Environment II: Effects, Modeling, and Control, Air and Waste Management Association, Atlanta. Wagner, K. K., N. J. M. Wheeler, and D. L. McNerny. 1992. The Effect of Emission Uncertainty on Urban Airshed Model Sensitivity to Emission Reductions. Presented at Symposium on Tropospheric Ozone: Nonattainment and Design Value Issues, Air and Waste Management Association, Boston, October 28, 1992. Weisskopf, M. 1992. EPA won't tighten urban ozone standard. Washington Post, August 4, p. Al. White, W. H., J. A. Anderson, D. L. Blumenthal, R. B. Husar, N. V. Gillani, and J. D. Husar. 1976. Formation and transport of secondary air pollutants: Ozone and aerosols in the St. Louis urban plume. Science 194: 187-189. . .

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Keeping Pace with Science and Engineering: Case Studies in Environmental Regulation Get This Book
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The technical basis of environmental regulation is always at the edge of scientific and engineering understanding. As knowledge improves, questions will inevitably arise about past decisions. Understanding how the regulatory system accommodates changing scientific and engineering knowledge is vital for achieving environmental values.

In this new volume, seven case studies shed light on the interplay between environmental regulation and scientific and engineering understanding, with practical conclusions on how science and engineering should be used for more sound and timely regulatory decision making. The book provides helpful timelines of scientific and regulatory developments for the cases, which include:

  • Factors impeding clean-up strategies in the Chesapeake Bay.
  • Pivotal questions in the regulation of ambient ozone concentrations.
  • How science has been heeded but also ignored in regulation of new municipal waste combustors.
  • Impact of scientific findings on control of chlorination by-products.
  • Acid rain and what can be learned about research and public policy debate.
  • Controversy over the need for formaldehyde regulation.
  • The effect of public perception on management decisions concerning dioxin.

This volume will be of practical interest to policymakers, business and environmental advocates, scientists, engineers, researchers, attorneys, faculty, and students.

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