regions of the United States indicates that many people may be exposed to concentrations of ozone that EPA has determined to be potentially harmful. EPA reported that in 1989, about 67 million people lived in areas where the second-highest ozone concentration, a principal measure of compliance, exceeded the NAAQS concentration. Despite considerable regulatory and pollution control efforts over the past 20 years, high ozone concentrations in urban, suburban, and rural areas of the United States continue to be a major environmental and health concern.
The nationwide extent of the problem, coupled with increased public attention resulting from the high concentrations of ozone over the eastern United States during the summer of 1988, adds to the urgency for developing effective control measures. As the ozone attainment strategy presented in the 1990 amendments to the Clean Air Act is put into effect, the success of efforts to control the precursors of ozone will be of vital concern to Congress, to governmental regulatory agencies, to industry, and to the public.
The Committee on Tropospheric Ozone Formation and Measurement was established in 1989 by the Board on Environmental Studies and Toxicology of the National Research Council (NRC) in collaboration with the NRC's Board on Atmospheric Sciences and Climate to evaluate scientific information and data bases relevant to precursors and tropospheric formation of ozone, and to recommend strategies and priorities for filling critical scientific and technical gaps in the information and data bases. The committee's members had expertise that included atmospheric chemistry, measurement, mathematical modeling, pollution trends monitoring, transport meteorology, exposure assessment, air-pollution engineering, and environmental policy. The committee was specifically charged to address
• Emissions of VOCs (anthropogenic and biogenic2) and NOx;
• Significant photochemical reactions that form ozone, including differences in various geographic regions;
• Effects of precursor emissions on daily patterns of ozone concentration;
• Ambient monitoring techniques;
2''Anthropogenic emissions'' refers to emissions resulting from the actions of human society. "Biogenic emissions" refers to natural emissions, mainly from trees and other vegetation.