Criteria pollutants

Each year, EPA pubHshes a summary of air pollution emissions and air quaUty trends for the criteria pollutants (4). Table 1 contains the summary for 1989. U.S. emissions estimates for these pollutants are available back to 1940 (5). 

Receptors. The receptor can be a person, animal, plant, material, or ecosystem. The criteria and hazardous air pollutants were so designated because, at sufficient concentrations, they can cause adverse health effects to human receptors. Some of the criteria pollutants also cause damage to plant receptors. An Air QuaUty Criteria Document (12) exists for each criteria pollutant and these documents summarize the most current Hterature concerning the effects of criteria pollutants on human health, animals, vegetation, and materials. The receptors which have generated much concern regarding acid deposition are certain aquatic and forest ecosystems, and there is also some concern that acid deposition adversely affects some materials. 

Table 3. National Ambient Air Quality Standards for Criteria Pollutants ...

Since SO2 and NO2 are criteria pollutants, their emissions are regulated. In addition, for the purposes of abating acid deposition in the United States, the 1990 Clean Air Act Amendments require that nationwide SO2 and NO emissions be reduced by approximately 10 million and 2 million t/yr, respectively, by the year 2000. Reasons for these reductions are based on concerns which include acidification of lakes and streams, acidification of poorly buffered soils, and acid damage to materials. An additional major concern is that acid deposition is contributing to the die-back of forests at high elevations in the eastern United States and in Europe. 

The process of evaluating air emission permit apphcations for large sources which are subject to federal permitting requirements is called New Source Review (NSR) and can be quite complicated, taking from six mouths to four years to complete. An NSR application would be required for a new source which could emit 100 tons per year or more of any criteria pollutant, after accounting for any air pollution control equipment. 

Criteria (in the context of criteria pollutants) information on health and/or environmental effects of pollution. 

Location of nonattainment areas for criteria pollutants, September 1998. 

Highly toxic air pollutants fall under Section 112 of the Clean Air Act. Unlike criteria pollutants, these hazardous air pollutants must be controlled to protect the public health with an "ample margin of safety." Implied in this language is the belief in a discrete threshold of exposure below which no effects occur and from which a safety margin can be measured. Subsequent interpretations, however, indicated clearly that Congress did not equate safeguarding the public health with complete risk elimination. 

Air/liquid (A/L) interface, adsorption of surfactants at, 24 133-138 Air mass zero (AMO) spectrum, 23 37 Air monitoring, for hydrazine, 13 589 Air oxidized pan, 11 194 Air-path XRF, in fine art examination/ conservation, 11 403—404 Air pollutants. See also Nitrogen oxides (NO j Particulate matter Sulfur oxides (SOJ Volatile organic compounds (VOCs) air toxics, 1 789, 801-802 carbon monoxide, 1 789, 798 common, 26 667 criteria pollutants, l 813t indoor, 1 802-805, 820-823, 821t lead, 1 789, 801... 

EPA, Office of Air Quality, Permissible Standards, Criteria Pollutants. 

EPA, Standing Air Monitoring Work Group List of Non-Criteria Pollutants. 

The NAAQS in effect as of June 2004 are summarized in the chart on pages 53-54. Note that only six air pollutants are included in this table carbon monoxide, nitrogen dioxide, ozone, lead, particulate matter, and sulfur dioxide. These pollutants are called criteria pollutants. 

The quality of the nation s air has clearly improved since Earth Day 1970. Air quality measurements for all six criteria pollutants have improved, in some cases quite dramatically. The battle to control pollution is hardly over, however. As this chapter has indicated, emissions of many pollutants continue to increase. The dialogue continues between those who wish to regulate air quality more rigorously and those who prefer to move more slowly and protect economic growth. There seems little doubt that that debate will continue well into the future. 

A number of pollutants have documented effects on people, plants, or materials at concentrations, or approaching those, found in polluted air (e.g., see Bascom et al., 1996a,b). In the United States, seven of them are known as criteria, pollutants and national ambient air... 

The United States sets two types of NAAQS, primary and secondary. They are based on information contained in air quality criteria documents that contain a wealth of information on all aspects of the criteria pollutants, as do the documents by the World Health Organization. These should be consulted for detailed information and references regarding pollutant sources, ambient levels, chemical transformations, effects, and so on. 

In addition to the criteria pollutants, a wide variety of trace gaseous and particulate species are present in the polluted troposphere (Finlayson-Pitts and Pitts, 1997). Table 2.9 shows some of these gaseous noncriteria pollutants identified in photochemical air pollution and gives typical concentrations under conditions ranging from those in remote areas to severely polluted urban air (see also Chapter 11). 

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