Air pollution is a serious health threat in California. According to the California Air Resources Board (ARB), over 90 percent of Californians breathe unhealthy levels of one or more air pollutants during some part of the year. ARB maintains over 40 monitoring stations in the State, which measure criteria pollutants and some toxic air contaminants.
By inhaling particles and gases, air pollution can cause inflammation and obstruction in the airways which can lead to or exacerbate respiratory conditions such as asthma, bronchitis, and chronic obstructive pulmonary disease (COPD). Evidence exists that exposure to particles and gases can interfere with normal host defense mechanisms in the lung and increase infection susceptibility (Animal Models to Study for Pollutant Effects, U.P. Kodavanti and D.L. Costa; in Air Pollution and Health, 1999). Small diesel particles can penetrate deep in the lung and, as they are coated with carcinogenic Polycyclic Aromatic Hydrocarbons, can cause lung cancer. High pollution events can exacerbate respiratory illness, while long-term exposure is related to reduced lung capacity and function, respiratory disease, and shortened lives.
Exposure to air pollution during pregnancy has also been associated with reduced birthweight, prematurity, and infant death.
According to ARB, long-term exposure to PM2.5 alone results in 14,000 to 24,000 premature deaths annually in California.