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Areas in Nonattainment of National Ambient Air Quality Standards for Criteria Pollutants
(Condensed nonattainment area list as of November 30, 2019)
Reference numbers 1-111 do not indicate ranking.
The "Total exposed" values represent estimated population living in areas that are in nonattainment for at least one pollutant.
KEY: O3 = ozone; Pb = lead; PM-10 = particulate matter smaller than 10 micrometers; PM-2.5 = particulate matter smaller than 2.5 micrometers; SO2 = sulfur dioxide.
a States are listed alphabetically. Some states on a row may be nonattainment for some pollutants and not for others in the general area. A multi-state area with states that have not all been redesignated to maintenance is counted as a nonattainment area until all of the states in the area are redesignated, with the whole area population displayed.
b This is a simplified listing of classified nonattainment areas. Unclassified and Section 185a (transitional) nonattainment areas are not included. Note that several smaller nonattainment areas may be inside one larger nonattainment area. In these cases, the smaller nonattainment areas are listed on the same line as the larger one, and the number of nonattainment areas are indicated under each pollutant.
c Guam (U.S. territory)
d National total includes Guam (U.S. territory).
e The number of nonattainment areas for each of the criteria pollutants is listed.
f The 8-hour Ozone (1997) standard was revoked on April 6, 2015 and the 1-hour Ozone (1979) standard was revoked on June 15, 2005.
g Population figures were obtained from the 2010 census data. For nonattainment areas defined as only partial counties, population figures for just the nonattainment area were used when these were available. Otherwise, whole county population figures were used. When a larger nonattainment area encompasses a smaller one, double counting the population in the "Total exposed" column is avoided by only counting the population of the larger nonattainment area.
U.S. Environmental Protection Agency, Office of Air Quality and Standards, Green Book, Summary Nonattainment Area Population Exposure Report, available at https://www3.epa.gov/airquality/greenbook/popexp.html as of Nov. 19, 2019.