| Year | |||||||||
| 1991 | 1992 | 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | |
| Based on 1990 population, in millions | |||||||||
| Population | 150.53 | 148.86 | 147.07 | 145.28 | 132.48 | 122.75 | 119.00 | 113.00 | 105.00 |
Source: U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, National Air Quality and Emissions Trends Report, 1998 (EPA, OAQPS, Research Triangle Park, NC, 2000) and earlier trends reports.
Notes: When an area does not meet the air quality standard for one of the criteria pollutants it may be subject to EPA’s formal rule-making process which designates it as nonattainment. Population figures were obtained from 1990 census data. For nonattainment areas defined as only partial counties, population figures for just the nonattainment areas were used when these were available. Otherwise, whole county population figures were used. Population estimates in this table differ from those presented in Table 5.12 because formal nonattainment designations are based on multiple years data rather than a single year and generally do not follow county boundaries. For example, ozone nonattainment areas typically compose the entire metropolitan area, which may include additional counties that do not contain air quality monitors.)
Last Updated on