- Asbestos is a term used for several types of naturally-occurring fibrous minerals found in many parts of California.
The most common type of asbestos is chrysotile, but other types are also found in California. Serpentine rock often
contains chrysotile asbestos. Serpentine rock, and its parent material, ultramafic rock, is abundant in the Sierra
foothills, the Klamath Mountains, and Coast Ranges. Serpentine rock is typically grayish-green to bluish-black
in color and may have a shiny appearance.
- Asbestos is commonly found in ultramafic rock, including serpentine, and near fault zones. The amount of asbestos
that is typically present in these rocks range from less than 1% up to about 25%, and sometimes more. Asbestos
is released from ultramafic and serpentine rock when it is broken or crushed. This can happen when cars drive over
unpaved roads or driveways which are surfaced with these rocks, when land is graded for building purposes, or at
quarrying operations. It is also released naturally through weathering and erosion. Once released from the rock,
asbestos can become airborne and may stay in the air for long periods of time.
- All types of asbestos are hazardous and may cause lung disease and cancer. Health risks to people are dependent
upon their exposure to asbestos. The longer a person is exposed to asbestos and the greater the intensity of the
exposure, the greater the chances for a health problem. Asbestos-related disease, such as lung cancer, may not
occur for decades after breathing asbestos fibers. Cigarette smoking increases the risk of lung cancer from asbestos
- Other sources of asbestos are in man-made products. The most common sources are heat-resistant insulators,
cement, furnace or pipe coverings, inert filler material, fireproof gloves and clothing, and brake linings. Asbestos
has been used in the United States since the early 1900's; however, asbestos is no longer allowed as a constituent
in most home products and materials. Many older buildings, schools, and homes still have asbestos containing products.
Therefore, laws are in place to protect citizens when these buildings are renovated or demolished.
- There are many laws pertaining to asbestos. The Air Resources Board adopted two statewide control measures
which prohibits the use of serpentine or ultramafic rock for unpaved surfacing and controls dust emissions from
construction, grading, and surface mining in areas with these rocks. There may be additional or more stringent
laws concerning asbestos in your area - please contact your local air pollution control district for further information.
For further information please see:
Fact Sheet #1: Health Information on Asbestos
Fact Sheet #2: School Advisory for Naturally-Occurring Asbestos
Fact Sheet #3: Ways to Control Naturally-Occurring Asbestos Dust
Fact Sheet #4: Naturally-Occurring Asbestos Around Your Home
Fact Sheet #5: Monitoring for Asbestos