Air Quality Management in the United States (2004) / Chapter Skim
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2 Setting Goals and Standards
2 Setting Goals and Standards
Pages 45-87
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From page 45... ...
to provide technical and financial assistance to State and local govern ments in connection with the development and execution of their air pol lution prevention and control programs; and (4) to encourage and assist the development and operation of regional air pollution prevention and control programs.
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From page 46... ...
. · The setting of emission standards for a variety of stationary and mobile sources for substances that are the criteria pollutants, their precursors, or hazardous air pollutants (HAPs)
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THE STANDARD-SETTING PROCESSES Criteria Pollutants Criteria pollutants were first defined in the 1970 Amendments to the CAA, which directed the administrator of EPA to identify those widespread ambient air pollutants that are reasonably expected to present a danger to public health or welfare.2 On the basis of air quality criteria3 -- that is, the current state of scientific knowledge on the effects of these pollutants on health and welfare -- the administrator is directed to develop and promulgate primary and secondary NAAQS for each criteria air pollutant. In addition to specifying a maximum ambient concentration for each pollutant, promulgation of a standard must also include descriptions of the moni 2Within the framework of the CAA, "welfare" refers to the viability of agriculture and ecosystems (such as forests and wildlands)
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From page 48... ...
. The Procedure for Setting NAAQS The CAA instructs the EPA administrator to specify primary and secondary NAAQS and to conduct a review of the air quality criteria and NAAQS for each pollutant at least every 5 years.
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From page 49... ...
and putting in place the 8-hr, 0.08-ppm standards. However, the 0.12-ppm standards will not be revoked in a given area until that area has achieved 3 consecutive years of air quality data meeting the 1-hr standard.
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Next, EPA's Office of Air Quality Planning and Standards (OAQPS) in the Office of Air and Radiation prepares a document, called the staff paper, which recommends and provides the justification for policy options presented to the EPA administrator, who makes a determination on whether to retain an existing standard or propose a new one.
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From page 51... ...
Protection of Ecosystems and the Establishment of Secondary NAAQS Although the CAA empowers EPA to set independent primary and secondary standards for each criteria pollutant, and criteria documents prepared by EPA have included reviews of the available data on impacts to ecosystems, visibility, human-made structures, and other aspects of public welfare, SO2 is the only criteria pollutant for which there is a unique secondary standard (Table 2-1)
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52 In to since ozone EPA (TSP)
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From page 53... ...
air quality problems.5 Thus, the nation's AQM system may now be in a better position to tackle the problem of air pollution damage to sensitive ecosystems and crops. In the CAA Amendments of 1990, Congress instructed EPA to undertake a comprehensive review of the need for and use of standards to protect public welfare (42 USC § 7409 [1990]
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From page 54... ...
To that end, the CAA includes a number of programs to reduce criteria pollutant emissions from stationary and mobile sources. As noted earlier, these national controls have been implemented in large part by setting specific emission standards within the act itself or, barring that, by providing specific instructions to the EPA administrator.
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From page 55... ...
However, since passage of the CAA Amendments of 1990, one compound has been deleted from the list (caprolactam) , the scope of chemicals covered by glycol ethers was reduced, and no compound has been added to the list.7 Current Standard-Setting Procedure for HAPs In contrast to criteria pollutants for which ambient concentration standards are used, the control of HAPs is based on an initial promulgation of emission standards and a subsequent assessment of risk that remains after implementation of these standards (the CAA defines this remaining risk as the "residual risk")
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From page 56... ...
hazardous air pollutants that present the greatest threat to public health in the largest number of urban areas are subject to regulation." In the case of major sources, 174 different types of sources were identified as emitters of HAPs and targeted for regulation by Congress. In a separate portion of the CAA Amendments of 1990 (Section 202)
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From page 57... ...
Then, in the absence of any specific action by Congress for a 2-year period following issuance of the report, the EPA administrator was to promulgate additional emission standards to "provide an ample margin of safety to protect public health or to prevent, taking into consideration costs, energy, safety, and other relevant factors, an adverse environmental effect." The promulgation of these additional emission standards was to occur no later than 8 years after EPA's initial promulgation of the technology-based standards. Although no formal standard for acceptable residual risk was mandated in the CAA Amendments of 1990, the act cited an example of such a standard: the reduction of excess cancer risk for the most exposed individuals to less than 1 in 1 million for a lifetime of exposure to a particular HAP.
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From page 58... ...
program for O3 nonattainment areas that for the first time required caps on a number of toxic and volatile constituents of gasoline, especially benzene. In Section 202, the 1990 CAA Amendments also required the mobilesource HAPs program to conduct a motor-vehicle-source HAPs study and to promulgate regulations.
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From page 59... ...
In response to growing concerns about deteriorating visibility in our nation's recreational areas, the CAA Amendments of 1977 (Section 169A) established a national goal of preventing and remedying visibility impairment due to anthropogenic pollution in Class I areas, which include most U.S.
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poor air quality in Big Bend National Park.
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Controls on Acid Rain Precursors before the CAA Amendments of 1990 The establishment of NAAQS for SO2 and NO2 as a result of the CAA Amendments of 1970 marked the beginning of a nationwide program to control their emissions. (In addition to the NAAQS, EPA, pursuant to the 1970 CAA Amendments, imposed a new-source performance standard (NSPS)
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The CAA Amendments of 1977 required EPA to address new coal utility plants (those built after 1978)
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SETTING GOALS AND STANDARDS 63 35 SO2 30 On-road Miscellaneous tons) 25 short Non-road 20 Industrial Processing (million 15 10 Emissions Fuel Combustion 5 0 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 Year Fuel Combustion Industrial Processing On-road Non-road Miscellaneous 30 NO2 25 tons)
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From page 64... ...
Acid Rain Goals Set by the CAA Amendments of 1990 Acid rain gradually emerged as a serious environmental concern in the late 1970s. A growing body of scientific evidence had accumulated that documented the deleterious impacts of acid rain on ecosystems, aquatic life, and property, particularly in regions where soils are acidic, such as eastern Canada and the northeastern United States.
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From page 65... ...
Language was also included to allow a state or group of states to petition the EPA administrator to use a cap-and-trade program instead of emission standards to meet Congress's NOx reductions goals. A more detailed discussion of the SO2 and NOx acid-rain emission-control programs and their implementation can be found in Chapter 5.
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From page 66... ...
In February 1994, the President of the United States issued Executive Order 12898 on environmental justice. That order was designed to focus federal attention on the environmental 10Hot spots are locales where pollutant concentrations are substantially higher than concentrations indicated by ambient outdoor monitors located in adjacent or surrounding areas.
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From page 67... ...
THE SCIENTIFIC BASIS FOR SETTING STANDARDS The CAA directs the EPA administrator to set primary NAAQS to protect human health with "an adequate margin of safety," and to set secondary NAAQS to "protect the public welfare from any known or anticipated adverse effects associated with" a criteria pollutant. It similarly directs the EPA administrator to set emission standards for HAPs on the basis of an assessment of the residual risk they pose following implementation of MACT and GACT.
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From page 68... ...
In B, the different lines are to indicate that the response to pollutants typically varies substantially among plant species or among varieties within a given species. Dose-response relationships for health effects are usually plotted with risk increasing with increasing dose, but dose-response relationships for welfare effects are often plotted in terms of a diminishing return as a function of exposure.
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From page 69... ...
SOURCE: HEI 2000. Reprinted with permission; copyright 2000, Health Effects Institute.
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From page 70... ...
In addition to observations of the concentration of the pollutant of interest, epidemiological studies require data on many other parameters that can affect health -- such as meteorological condition and the concentrations of other pollutants -- so that the influence of these potentially confounding influences on health outcomes can be accounted for. As noted in Chapter 1, identifying and quantifying the health impact of a specific pollutant is a challenging task and typically requires the use of large sample sizes and sophisticated statistical methods.
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From page 71... ...
. In this approach, selected members of a population are given personal exposure monitors to develop a quantitative record of their actual exposure to air pollutants and, at the same time, are carefully monitored for signs of any related adverse health effects.
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; (2) field studies, in which effects of air pollutants on ecosystems and the biotic components of these are monitored; (3)
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; and (4) hybrid studies, in which chamber experiments are conducted in the field using filters to scrub pollutants, such as O3 so that exposure concentrations are less than those at ambient conditions, or pollutant concentrations are increased above ambient concentrations (see Figure 2-12)
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From page 74... ...
One potential technique that might be useful for examining longterm effects of air pollutants on intact ecosystems has thus far been applied to studies of the long-term ecological effects of increased atmospheric carbon dioxide (CO2) and is referred to as free air CO2 enrichment (FACE)
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From page 75... ...
This hybrid approach might include long-term measurements of air pollutants and their changes, associated ecosystem response to these changes, and coupled integrated experiments and model applications. An example of a site where this hybrid approach has been implemented is at the Hubbard Brook Experimental Forest in New Hampshire.
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From page 76... ...
For example, a large body of both animal and human experimental evidence on O3 is available, and as a result, the O3 NAAQS has been set with a great reliance on experimental data. For PM, on the other hand, direct human effects studies are scarce, and the bulk of the scientific evidence used to develop the PM NAAQS in 1997 came from epidemiological studies using mostly PM10 data from atmospheric monitoring.
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From page 77... ...
, the possibility that concentration thresholds may not exist for some pollutants raises serious questions about the technical feasibility of setting primary NAAQS that are consistent with the language in the CAA. In it, the EPA administrator is required to set primary NAAQS to protect public health with "an adequate margin of safety." Implicit in this FIGURE 2-14 Concentration-response estimation from the reanalysis of the Pope/ American Cancer Society Study on cardiopulmonary disease mortality (excluding Boise, Idaho)
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From page 78... ...
It would also require accurate quantitative estimates of the nature and extent of adverse health affects in sensitive populations, and the models upon which such estimates might be based are currently clouded in considerable scientific uncertainty. Static List of Hazardous Air Pollutants At the national level, toxic air pollutants are controlled when they are listed as hazardous air pollutants (HAPs)
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From page 79... ...
. However, because the toxicology of PBDEs is not well-documented, these compounds are unregulated air pollutants at the federal level in the United States.
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From page 80... ...
Limitations of Establishing Standards for One Pollutant at a Time The CAA directs the EPA administrator to establish air quality standards for individual criteria pollutants and HAPs in isolation from other pollutants. That approach has contributed to the development of an AQM system in the United States that tends to focus on only one pollutant at a time, probably introduces inefficiencies into the pollution control program, and might even give rise to unintended consequences.
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From page 81... ...
Thus, policy makers identified "target loads" that accounted for economic and political considerations as an intermediate step to reducing emission levels to below critical load levels. The UNECE chose to set an interim load that would reduce the 1980 exceedance level by 60% by 2010.
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From page 82... ...
The latter approach can be hampered by the strong correlations that sometimes exist between air pollutants; the correlations can make it difficult or even impossible to separate the effects of one pollutant from another. Health effects studies that focus on sources instead of individual pollutants offer one method for moving away from an AQM system focused on single pollutants to one focused on multipollutant controls.
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From page 83... ...
Need to Address Health Risk Associated with Exposure in Hot Spots and Indoor Environments There is a growing recognition within the scientific and regulatory communities of the potential importance of pollutant exposure in special microenvironments or hot spots. These environments may include highway toll plazas, truck stops, airport aprons, and areas adjacent to one or many stationary sources or busy roadways, as well as transit within vehicles and indoor environments.
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From page 84... ...
. However, no federal statutes specifically give EPA authority to regulate indoor residential and commercial sources of air pollutants -- perhaps because of a reluctance on the part of CA ET CAI ( CI + CAI )
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From page 85... ...
Second, the final report of the National Commission on Risk Assessment and Risk Management, established in the CAA Amendments of 1990, found that risk assessment can be a powerful tool for setting priorities on resources for monitoring and regulating the myriad air pollutants to which humans, ecosystems, and materials are regularly exposed (NCRARM 1997)
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From page 86... ...
Another major deficiency is our inability to assess pollutant exposures accurately because of a lack of sufficient data on the distribution of pollutants. If these deficiencies are to be addressed, substantial investments over a substantial period of time will be needed for research on air pollution effects research and for more advanced systems to determine the spatial and temporal variability of air pollutants in specific hot spots and in indoor environments as well as the ambient air.
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From page 87... ...
· It is a significant challenge to set ambient or emission standards to protect public health with an adequate margin of safety from harmful exposure to a pollutant if that pollutant does not exhibit a threshold concentration for an adverse health effect. 12 Recommendations that address these limitations are provided in Chapter 7.
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