The following table shows San Diego County's federal and state designations for each of the criteria pollutants:
|Criteria Pollutant||Federal Designation||State Designation|
|Ozone (1-Hour)||Attainment *||Nonattainment|
|Sulfates||No Federal Standard||Attainment|
|Hydrogen Sulfide||No Federal Standard||Unclassified|
|Visibility||No Federal Standard||Unclassified|
* The federal 1-hour standard of 12 pphm was in effect from 1979 through June 15, 2005. The revoked standard is referenced here because it was employed for such a long period and because this benchmark is addressed in State Implementation Plans.
** At the time of designation, if the available data does not support a designation of attainment or nonattainment, the area is designated as unclassifiable.
What is meant by attainment?
An area is designated in attainment when it is in compliance with the National and/or California Ambient Air Quality Standards. These standards are set by the federal Environmental Protection Agency (EPA) or the California Air Resources Board (CARB) for the maximum level of a given air pollutant which can exist in the outdoor air without unacceptable effects on human health or the public welfare.
Why are there both state and federal standards?
Both the United States Government and the State of California have enacted legislation designed to improve air quality. The 1970 federal Clean Air Act covers the entire country. This law (and its amendments in 1977 and 1990) allows individual states to have stronger standards, but states cannot have weaker standards than those set for the entire country. California adopted its own stricter standards in its Clean Air Act of 1988.