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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

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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 . ~

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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. .~

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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 \

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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.

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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 ....

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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

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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 .'

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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 ..

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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. ,.,

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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

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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. .

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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

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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. , . . .

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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

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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 ~ .

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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.

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