Naturally Occurring Asbestos (NOA)

Serpentine rock with veins of asbestos.

Naturally occurring asbestos (NOA) includes fibrous minerals found in certain types of rock formations. NOA can take the form of long, thin, separable fibers. Natural weathering or human disturbance can break NOA down to microscopic fibers, easily suspended in air.

There is no health threat if NOA remains undisturbed and does not become airborne. When airborne NOA is inhaled, these thin fibers irritate tissues and resist the body's natural defenses. Asbestos, a known carcinogen, causes cancers of the lung and the lining of internal organs, as well as asbestosis and other diseases that inhibit lung function. Covering NOA with clean soil or planting grass reduces exposure.

Here are more resources on NOA:

Naturally Occurring Asbestos: Approaches for Reducing Exposure (PDF) (7 pp, 85K, about PDF) - This fact sheet provides an overview of approaches for reducing exposures to NOA. The fact sheet describes existing work practices and engineering and institutional controls that have been implemented at the state or local level to reduce exposures to NOA. The fact sheet is intended to serve as a practical starting point for state and local government leaders addressing NOA issues in their localities.
2005 US Geological Survey Report - A report published by the USGS on July 1, 2005, contains a regional map and an associated database that includes 324 locations where naturally occurring asbestos has been historically identified in the Eastern United States. Read the news release.
NOA in California - In May 2005, the EPA completed a comprehensive investigation to assess the potential for exposure from naturally occurring asbestos in El Dorado County, California. Information about this investigation as well as sampling results and continuing plans are detailed on Region 9's NOA, El Dorado Hills Web pages.

Related Links

EPA's Integrated Risk Information System (IRIS) Asbestos page - IRIS is a database of human health effects that may result from exposure to various substances found in the environment. The information in IRIS is intended for those without extensive training in toxicology but with some knowledge of health sciences.
Main USGS asbestos section - The USGS asbestos section offers links to publications and fact sheets about all six fibrous minerals.
Agency for Toxic Substances and Disease Registry (ATSDR) asbestos section - ATSDR offers detailed information on asbestos and health.

Naturally Occurring Asbestos (NOA)

Local Navigation