Air Quality Management in the United States (2004) / Chapter Skim
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1 Introduction
1 Introduction
Pages 23-44
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From page 23... ...
All of these components depend on robust and up-to-date scientific and technical input, which includes an understanding of relationships between air pollutant levels and impacts on human health, ecosystems, atmospheric visibility, and materials. The National Research Council Committee on Air Quality Management in the United States was asked to evaluate the effectiveness of the nation's air quality management (AQM)
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up to 50 km altitude, are addressed only in the context of managing ground-level air quality.2 The science of air pollution is primarily concerned with quantitatively understanding the so-called "source-receptor relationships" that link specific pollutant emissions to the pollutant concentrations and deposition observed in the environment as a function of space and time. This quantitative understanding is developed through extensive field and laboratory measurements and analysis and is then tested and documented in air quality models that use mathematical and numerical techniques to simulate the physical and chemical processes that affect air pollutants as they disperse and react in the atmosphere.
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Air pollutants are often characterized by how they originate: pollutants emitted directly into the atmosphere are called primary pollutants; those formed as a result of chemical reactions within the atmosphere are called secondary pollutants. Control of secondary pollutants is generally more problematic than that of primary pollutants, because mitigation of second
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For example, many of the VOCs that react to form O3 are also identified as hazardous air pollutants 3Nitric oxide (NO) and nitrogen dioxide (NO2)
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, nitric oxide and nitrogen dioxide (NOx) , volatile organic compounds (VOCs)
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. The scientific techniques for assessing health impacts of air pollution include air pollutant monitoring, exposure assessment, dosimetry, toxicology, and epidemiology (NRC 1998b, 1999a)
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In addition, such pollutants as sulfate can accelerate the natural weathering process of materials, including metals, painted surfaces, stone, and concrete. AIR QUALITY MANAGEMENT IN THE UNITED STATES As the health, ecological, and economic impacts of air pollution in the United States have become increasingly evident through more sophisticated scientific approaches, the nation has endeavored to protect air quality through increasingly complex and ambitious legislation (Table 1-1)
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Aircraft emission standards to be developed by EPA Automotive emission standards for hydrocarbons and CO for 1975 models and for NOx for 1976 models States allowed to adopt air quality standards more stringent than federal standards Motor vehicle emissions inspection and maintenance (I/M) program Citizens allowed to sue for air pollution violations 1977 Clean Air Act Geographic regions (Classes I, II, III)
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CO emissions standards set at 10 g/mile beginning in 1994 "Clean car" (ZEV, electric car) pilot program in California 150,000 vehicles by model year 1996 300,000 vehicles by model year 1999 Title III: Toxics Emissions of 189 hazardous air pollutants (HAPs)
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Five major goals for protecting and promoting human health and public welfare are identified in the CAA as amended: · Mitigating potentially harmful human and ecosystem exposure to six criteria pollutants: CO, NO2, SO2, O3, PM, and lead (Pb) .4 · Limiting the sources of and risks from exposure to HAPs, which are also called air toxics.
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The federal government's role is coordinated by EPA and is intended in part to provide a degree of national uniformity in air quality standards and approaches to pollution mitigation so that all individuals in America are assured a basic level of environmental protection. State and local governments are given much of the responsibility for implementing and enforcing the federally mandated rules and regulations within their jurisdictional domains, including developing and implementing specific strategies and control measures to meet national air quality standards and goals.
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· Compliance assurance FIGURE 1-3 Idealized schematic showing three of the four sequential activities carried out by the nation's air quality management system. The fourth iterative activity involves a return to activities 1 and/or 2 to account for new information to correct deficiencies identified in step 3.
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3. Quantifying the expected demographic and economic trends with and without air pollution control strategies to better account for growth in activity that might offset pollution control measures and to better design control strategies that are compatible with the economic incentives of those who must implement them.
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6. Designing and implementing methods and technologies for tracking changes in pollutant emissions, pollutant concentrations, and human health and welfare outcomes to document and ultimately improve the effectiveness of air pollution mitigation activities.
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AQM in the United States involves the work of tens of thousands of people who monitor the concentrations of various air pollutants at over a thousand sites, regulate thousands of different emission sources, and maintain a multimillion dollar research and development program to better understand the sources, fate, and effects of air pollutants. The CAA requires regulatory control of air pollutants that have widely varying properties.
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From page 38... ...
Because it is difficult to isolate the effects of air pollution exposures from those of other risk factors that humans face daily, little direct empirical evidence is available to carry out the latter quantification. As a result, assessments of the benefits of pollution control often rely on complex models instead of direct empirical evidence.7 These models, in turn, tend to depend on a variety of estimated input parameters and assumptions.
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The SO2 provisions of the 1990 CAA Amendments alone account for $80 billion of the aggregate benefit estimate. THE FUTURE Despite the nation's significant progress in improving air quality, the problems posed by pollutant emissions in the United States are by no means solved.
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SOURCE: EIA 2000. County - violation 121 counties 75 M people FIGURE 1-6 Counties in the continental United States where any NAAQS were violated in 1999.
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. Perhaps even more important, new data on the health effects of O3 and PM led to the promulgation in 1997 of stricter NAAQS for O3 and new NAAQS for PM2.5 that will require even greater reductions in pollutant emissions than had been envisioned at the time the CAA Amendments of 1990 were enacted (see Figure 1-8)
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It also reviewed scientific and technical aspects of the policies and programs intended to manage important air pollutants, including but not limited to criteria pollutants and HAPs. In addition, the committee evaluated scientific and technical aspects of current approaches for health and environmental problem identification, regulatory standards development, AQM plan development, plan imple 8The committee's full Statement of Task is included in Appendix B
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A wide range of external factors beyond the scientific and technical aspects of air quality can drive the character and effectiveness of an AQM system and are relevant to our review. Governmental policies on economic growth, energy production and use, transportation, and land use, for example, affect pollutant emissions and can therefore reinforce or frustrate AQM policies.
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44 AIR QUALITY MANAGEMENT IN THE UNITED STATES decades, Chapter 7 provides a series of recommendations. In formulating these recommendations, the committee endeavored to look beyond the statutorily mandated constraints, methods, and approaches currently imposed on the nation's AQM system by the CAA and other relevant acts.
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