Automobiles and the infrastructure needed to support them, dominate American society. Despite stringent state regulations on both mobile and stationary emitters, California fails to meet EPA air quality standards more often than any other state in the nation. Several factors are involved in the Golden State's degraded air quality, including geography and topography, climate and large population. California's Central Valley counties currently experience worse ozone levels than New York, Houston, Philadelphia, and Chicago. California's poor air quality in the Central Valley affects more than just its human residents.
Ozone is the primary atmospheric pollutant causing injury to vegetation in California.
Together with other photochemical oxidants, ozone already causes estimated economic losses in the range of several hundred million U.S. dollars a year in California. Recent studies indicate that photosynthesis and growth rates in valuable tree crops such as almonds, apricots, plums, prunes, pears and apples, are substantially reduced when the plants are exposed to increased ambient levels of ozone such as is found at the University of California's field station located near Fresno. In addition to agricultural concerns, as air quality deteriorates, skin cancers and eye and respiratory problems are expected to increase in Central Valley livestock, especially in light-colored cattle and sheep. While there have been technological improvements in gasoline efficiency for motor vehicles, more people are driving more cars more miles on more trips. People travel farther to work and most people still drive to work alone.