Clean Air Act Amendments of 1970

The Clean Air Act Amendments of 1970 extended the geographical coverage of the federal program aimed at the prevention, control, and abatement of air pollution from stationary and mobile sources. The act transferred administrative functions assigned to the secretary of HEW to the newly created Environmental Protection Agency. The act provided for the first time national ambient air quality standards and national emission standards for new stationary sources. It initiated the study of aircraft emissions and imposed carbon monoxide, hydrocarbons, and nitrogen oxide emissions control on automobiles.

The major goal of the act was the achievement of clean air throughout the United States by the middle of the decade. Two types of pollutants were to be regulated: criteria air pollutants and hazardous air pollutants (HAPs). The criteria air pollutants were to be regulated to achieve attainment of National Ambient Air Quality Standards by establishing emission standards (developed by state and local agencies) for existing sources and national emission standards for new sources through promulgation of New Source Performance Standards. HAPs were to be regulated under National Emission Standards for Hazardous Air Pollutants. The major provisions of the act included [4]:

• The EPA was to establish National Ambient Air Quality Standards (NAAQSs), including primary standards for the protection of public health and secondary standards for the protection of public welfare;

• New Source Performance Standards (NSPSs) were to be required, with each state implementing and enforcing the standard of performance. Before a new stationary source could begin operation, state or federal inspectors were required to certify that the controls would function, and the new stationary sources had to remain in compliance throughout the lifetime of the plant;

• National Emission Standards for Hazardous Air Pollutants (NESHAPs) were to be established and would apply to existing as well as new plants;

• Funding was provided for fundamental air pollution studies, research on health and welfare effects of air pollutants, research on cause and effects of noise pollution, and research on fuels at stationary sources, including methods of cleaning fuels prior to combustion rather than flue gas cleaning techniques, improved combustion techniques, and methods for producing new or synthetic fuels with lower potential for creating polluted emissions;

• State and regional grant programs were authorized and matching grants established for implementing standards;

• The designation of AQCRs was to be completed;

• Establishment of statewide plans to be implemented (i.e., state implementation plans, or SIPs) and designed to achieve primary or public health standards within 3 years was required, and the overall plan had to be convincing as to its ability to meet and maintain the standards;

• Industry was required to monitor and maintain emission records and to make these records available to EPA officials, and the EPA was given the right of entry to examine records;

• Fines and criminal penalties were imposed for violation of implementation plans, emissions standards, and performance standards that were stricter than those under the earlier law;

• New automobile emission standards were set;

• Aircraft emission standards were to be developed by the EPA;

• Citizen's suits were permitted against those alleged to be in violation of emission standards, including the United States, and suits could be brought against the EPA administrator if he or she failed to act in cases where the law specified that action must be taken.

Air Quality Criteria and National Ambient Air Quality Standards

The Air Quality Act of 1967 addressed the development and issuance of air quality criteria (AQC), and the need for such criteria was reaffirmed in the 1970 amendments. AQC indicate qualitatively and quantitatively the relationship between various levels of exposure to pollutants and the short- and long-term effects on health and welfare [4]. AQC describe effects that can be expected to occur when pollutant levels reach or exceed specific values over a given time period and delineate the effects from combinations of contaminants as well as from individual pollutants. Economic and technical considerations are not relevant to the establishment of AQC.

The development of AQC is essential in providing a quantitative basis for air quality standards. Standards prescribe the pollutant levels that cannot be legally exceeded during a specific time period in a specific geographical region. The Clean Air Act Amendments of 1970 required federal promulgation of national primary and secondary standards that are to be established equitably in terms of the social, political, technological, and economic aspects of the problem. Standards are subject to revision as aspects change over time.

The purpose of the primary standards is immediate protection of the public health, including the health of sensitive populations such as people with asthma, children, and the elderly. Primary standards are to be achieved regardless of cost and within a specified time limit. Secondary standards are intended to protect the public welfare from known or anticipated adverse effects, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings. Both standards have to be consistent with AQC, and, in addition, the standards have to prevent the continuing deterioration of air quality in any portion of an air quality control region.

The Clean Air Act Amendments of 1970 defined the first six criteria pollutants as carbon monoxide, nitrogen dioxide, sulfur dioxide, total particulate matter, hydrocarbons, and photochemical oxidants, and NAAQSs were established for these; subsequently, the list has been revised with the following actions [4]:

• The photochemical oxidant standard was revised and restated as ozone in 1979;

• The hydrocarbon standard was withdrawn in 1983;

• The total suspended particulate matter standard was revised in 1987 to include only particles with an aerodynamic particle size of <10 ^m and referred to as the PM10 standard;

• The PM2.5 (i.e., particles with an aerodynamic particle size of <2. 5 ^m) standard was added in 1997;

• In 1997, the EPA reviewed the air quality standard for ground-level ozone and established the primary and secondary 8-hour NAAQS for ozone at 0.08 ppm and the primary and secondary 1-hour NAAQS for ozone at 0.12 ppm.

The current list of NAAQSs is provided in Table 4-1 and includes carbon monoxide, nitrogen dioxide, ozone, lead, PM10, PM2.5, and sulfur dioxide [7].

National Emissions Standards

Emissions standards place a limit on the amount or concentration of a pollutant that may be emitted from a source. It is often necessary for certain industries to be regulated by emission standards promulgated by the federal or state government in order to maintain or improve ambient air quality within a region to comply with national or state air quality standards. A number of factors must be considered when establishing emission standards [4]:

• The availability of technology appropriate for cleanup of a given type of industry should be determined;

• Monitoring stations must be available to measure the actual industrial emissions for which control is considered, as well as the ambient air quality so that the effectiveness of the standards can be determined;

• Regulatory agencies must be organized to cope with the measurement and enforcement of the standards;

• The synergistic effects of various pollutants must be determined;

• Models must be developed that reasonably predict the effects of reducing various emissions on the ambient air quality;

• Reasonable estimates of future emissions must be made based on the growth or decline of industry and population within a region.

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