Did you know...
California has the cleanest industries, the cleanest utilities, the lowest car tailpipe emissions... yet still has the dirtiest air in the nation!

Click on a choice:

  Air Transport Corridors

  Pollution Sources

  Criteria Pollutants

  Meteorology

  Visibility

  Acid Rain/Snow

  Air Pollution Advisories

he activities of 35 million Californians can produce air pollution. Cars and trucks are the biggest source of emissions that contribute to air quality problems, but many other products and industrial processes release harmful chemicals into the air. If you live in or visit California, you contribute to the state's dirty air. California's terrain and weather also add to the problem.

The San Francisco Bay Area, the Central Valley, and the Los Angeles region are all ringed by mountains that can trap air pollution. During the summer, layers of warmer air in the upper atmosphere act as a lid over these areas. Under the hot sunlight, pollutants react to form ozone (the main ingredient of smog) as well as hazardous microscopic particles. In the winter, the air pollutants of concern are hazardous microscopic particles caused by activities such as wood burning, factory emissions and car exhaust. 

Click these links to see Northern Sierra air quality statistics:

Growth of population and light vehicles

Northern Sierra 2003 Air Pollutant Emissions

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