1. Criteria Pollutants Criteria pollutants selected because they are ubiquitous, have multiple sources, and "may reasonably be anticipated to endanger public health or welfare" (Section 108(a)(1)) Criteria pollutants selected because they are ubiquitous, have multiple sources, and "may reasonably be anticipated to endanger public health or welfare" (Section 108(a)(1)) carbon monoxide carbon monoxide lead lead nitrogen dioxide nitrogen dioxide ozone ozone particulate matter particulate matter sulfur dioxide sulfur dioxide Information, including criteria documents, staff papers, proposal and final Federal Register notices of decisions, and technical analyses available at: www.epa.gov/ttn/NAAQS Information, including criteria documents, staff papers, proposal and final Federal Register notices of decisions, and technical analyses available at: www.epa.gov/ttn/NAAQS www.epa.gov/ttn/NAAQS

2. Clean Air Act: National Ambient Air Quality Standards Program Sec. 109(b)(2): 2 nd NAAQS “shall specify a level of air quality the attainment and maintenance of which in the judgment of the Administrator, based on such criteria, is requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air.” Sec. 109(b)(2): 2 nd NAAQS “shall specify a level of air quality the attainment and maintenance of which in the judgment of the Administrator, based on such criteria, is requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air.”

3. Clean Air Act: National Ambient Air Quality Standards Program Section 108(a)(2): Section 108(a)(2): The Administrator shall issue air quality criteria…Air quality criteria for an air pollutant shall accurately reflect the latest scientific knowledge useful in indicating the kind and extent of all identifiable effects on public health and welfare which may be expected from the presence of such pollutant in the ambient air, in varying quantities…. The Administrator shall issue air quality criteria…Air quality criteria for an air pollutant shall accurately reflect the latest scientific knowledge useful in indicating the kind and extent of all identifiable effects on public health and welfare which may be expected from the presence of such pollutant in the ambient air, in varying quantities….

4. Clean Air Act: National Ambient Air Quality Standards Program Sec. 302 (h): Sec. 302 (h): All language referring to effects on welfare includes but is not limited to, effects on soils, water, wildlife, weather, visibility, and climate, damage to and deterioration of property, and hazards to transportation, as well as effects on personal comfort and well being, whether caused by transformation, conversion, or combination with other air pollutants.” All language referring to effects on welfare includes but is not limited to, effects on soils, water, wildlife, weather, visibility, and climate, damage to and deterioration of property, and hazards to transportation, as well as effects on personal comfort and well being, whether caused by transformation, conversion, or combination with other air pollutants.”

5. Review Process for NAAQS Scientific studies on health and environmental effects EPA Criteria Document – extensive assessment of scientific studies EPA Staff Paper – interprets scientific data and identifies factors to consider in setting standards including staff recommendations for standards Scientific peer review of published studies Reviews by CASAC and the public Public hearings and comments on proposals Proposed decision on standards Final decision on standards

6. Current National Ambient Air Quality Standards Primary Standards Secondary Standards Carbon monoxide 9 ppm or 10 mg/m3 (1 hr) 35 ppm or 40 mg/m3 (8 hr) None Lead 1.5 ug/m3 (quarterly) Same as primary Nitrogen Dioxide 0.053 ppm or 100 ug/m3 (annual) Same as primary PM10PM2.5 50 ug/m3 (annual) 150 ug/m3 (24 hr) 15 ug/m3 (annual) 65 ug/m3 (24 hr) Same as primary Ozone 0.08 ppm (8 hr) Same as primary Sulfur dioxide 0.03 ppm (annual) 0.14 ppm (24 hr) 0.5 ppm (3 hr)