A number of air pollutants coming out of a variety of industrial processes, impact the health of California residents. Two of the pollutants of the greatest concern from a public health perspective are fine particulate matter and ozone. Sources of PM2.5 include direct emissions from combustion of fuels such as gasoline, oil and diesel as well as wood combustion. PM2.5 is also formed in atmospheric chemical reactions of precursors emitted from combustion sources including motor vehicles. Pollution from diesel engines is part of PM2.5 and of particular concern due to its health impacts. Ozone is one of the major constituents of smog and is formed in the atmosphere by complex reactions with chemicals that are directly emitted from motor vehicles and other combustion sources.
The table below shows some of the common pollutants found in our air and examples of some of the sources of these pollutants.
Pollutant
Examples of Sources
Particulate Matter
(PM2.5 and PM10: less than or equal to 2.5 or 10 microns, respectively)
Cars and trucks (especially diesels)
Fireplaces, woodstoves
Windblown dust from roadways, agriculture and construction
Ozone (O3)
Precursor sources1
: motor vehicles, industrial emissions, and consumer products
Carbon Monoxide (CO)
Any source that burns fuel such as cars, trucks, construction and farming equipment, and residential heaters and stoves
Nitrogen Dioxide (NO2)
See carbon monoxide sources
Toxic Air Contaminants
Cars and trucks (especially diesels)
Industrial sources, such as chrome platers
Neighborhood businesses, such as dry cleaners and service stations
Building materials and products
1Ozone is not generated directly by these sources. Rather, chemicals emitted by these precursor sources react with sunlight to form ozone in the atmosphere.
