The San Joaquin Valley of California is a large geographic basin with a serious air pollution problem. It is subject to high summer temperatures and solar radiation. It has restricted air exchange because of surrounding mountains and low wind. Its population is growing and industry, vehicles and miles traveled are all increasing. The Valley could pass Los Angeles in the race to the bottom of air quality. It is already one of the three most polluted air basins in the United States.

Ozone generation and accumulation are of particular concern to agriculture, natural plants, and human health. Emissions of hydrocarbons and oxides of nitrogen from many sources lead to ozone air pollution. The Valley has been a very productive agricultural region, but this could be threatened by these increasing ozone concentrations. On many days, models suggest that yield could be reduced by 10-20% in many field and tree crops.

Air Pollution Levels

• California Air Resources Board - current and archived California air quality data for specific locations
• USEPA - static and animated ozone maps of the U.S. and Air Quality Index
• USEPA Air Now - daily simulation maps of ozone concentration. Select "San Joaquin Valley" for local conditions as they develop over time
• San Joaquin Valley Maps - most current air quality index information

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