Air quality standards are established to protect even the most sensitive individuals in our communities. There are both State of California and Federal Ambient Air Quality Standards (AAQS). These standards indicate the maximum amount of a pollutant that can be present in outdoor air without harm to the public's health. In some cases, the California AAQS is more stringent than the Federal AAQS. The District tracks the attainment status of the District under both standards.

The standards are pollutant specific and have two components; a pollution concentration value, and a time period of exposure. For example, the State standard for particulate matter 10 microns in size and smaller is 50 micrograms per cubic meter over a 24 hour time period (50ug/m3). The standards are designed to be conservative and, as such, are set at levels sufficient to protect a wide seqment of the population from health effects. The ambient air in portions of the District exceeds the State PM₁₀ standard during many of the winter months.

For more information check out the following links:

State of California:
Air Quality Standards and Area Designations
Area Designation Maps / State & National
California Ambient Air Quality Standards (CAAQS)

Federal / EPA:
Federal or National Ambient Air Quality Standards (NAAQS)