Criteria Air Pollutants

Learn about the findings from the Air District’s emissions inventory of criteria air pollutants.

To protect public health and the environment, the U.S. Environmental Protection Agency set national standards for six common air pollutants, known as criteria pollutants:

  • Ground-level ozone
  • Particulate matter
  • Carbon monoxide
  • Nitrogen dioxide
  • Sulfur dioxide
  • Lead

The Air District prepares emissions inventories of these criteria pollutants (except lead emissions, which are included in the toxic air contaminant reporting process).

Criteria Pollutant Emissions Inventory

The most recent emissions inventory of criteria pollutants is available in the Bay Area Emissions Inventory Summary Report for Criteria Air Pollutants: Base Year 2011 (PDF). The report summarizes emissions levels and trends from all major source categories, including stationary and mobile sources. Emission estimates are included for the year 2011, plus historical and future-year emission projects for 1990 through 2030.

Additional supporting documents and data for base year 2011 are also available.


There have been significant criteria pollutant emissions reductions from both stationary and mobile sources in the past several decades. This downward trend is a result of criteria pollutant control measures that have achieved air quality improvements despite regional growth in the local economy, population, and traffic.

Criteria Pollutants

Between 1990 and 2011, the Bay Area's economy (gross regional product, blue line) grew by about 77%, population increased by 23% (orange line), and the total number of miles driven increased by 30% (green line). However, criteria pollutant emissions and concentrations have decreased by about 60% (purple and red lines) during the same period.

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Last Updated: 3/24/2021