Valley air quality
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 surpass Los Angeles in terms of air pollution. 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 increasing ozone concentrations. On many days, models suggest that yield could be reduced by 10 to 20 percent in many field and tree crops due to air pollution.