Ambient Air Quality Standards
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.
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.