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Frequently Asked Questions: Indoor Exposures - Asbestos

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Q:  What is it?

A:  Asbestos is the general name that refers to a group of naturally occurring minerals that occur in a variety of fibrous forms including chrysotile, amosite, crocidolite, anthophoyllite, actinolite, and tremolite. Asbestos subtypes range in size from 0.1 to 10 microns in length (A human hair is about 50 microns in diameter).

Q:  Where can it be found?

A:  Asbestos is lightweight and heat resistant. These qualities have led to it’s use in a wide variety of materials for insulation, friction, fire protection, texturing, chemical resistance, decoration, and sound dampening purposes. In the US asbestos has been in use since the 1800s. Under the Clean Air Act and Toxic Substances Control Act, the EPA has banned certain asbestos-containing products including certain spray-applied surfacing materials, pipe-insulation, paper, and flooring felt.

Vermiculite ore mined in Libby, Montana may contain asbestos (sold under the brand Zonolite). This mine operated from 1919-1990 and supplied much of the world’s vermiculite used in attic and wall insulation. Additionally, Karstolite (from the Karst mine near Big Sky, MT) contains high levels of the anthophyllite form of the amphibole group of asbestos. Karstolite was used between 1925-late 1950s as insulation. Certain products in use today still contain asbestos such as floor tile, asbestos-cement, adhesives, roofing products, clutch and brake assemblies, etc. Because asbestos has been so widely used, it is thought that the entire US population has been exposed to some degree. It is estimated that 10 fibers/m3 are typically present in outdoor air in rural areas (a cubic meter of air is the amount a person breathes in one hour).

Q:  What are the adverse health effects related to asbestos exposure?

A:  Asbestos is a carcinogen. Asbestos fibers are small and lightweight and when disturbed become airborne and can remain in the air for a long time. Exposures are generally through inhalation or ingestion.  

When inhaled into the lungs, some of these tiny asbestos fibers are capable of penetrating deep into the respiratory tissue, causing adverse health effects and disease. Because these fibers are not efficiently removed from the body, subsequent exposures can lead to accumulation of asbestos and increased risk of disease. Health effects include asbestosis (permanent lung damage and scarring), lung cancers, mesothelioma (cancer of the lung or stomach lining), and cancers of other organs.

A number of factors can affect an individual’s susceptibility to asbestos-related disease including the levels of asbestos and length of exposure, the time since the exposure, and whether or not co-exposures such as tobacco smoke are present. Symptoms of these diseases generally do not appear until 10-30 years after the initial exposure.

Q: What regulations apply to asbestos?

A:  In Montana, activities involving asbestos in buildings are governed by one or more regulatory agencies, i.e. DEQ, EPA, and OSHA. In many cases jurisdictions and regulations overlap. Asbestos regulations that apply to public and commercial buildings differ from those that apply to residential dwellings, schools, and other buildings. Generally speaking, the Asbestos Control Program of the Montana DEQ regulates asbestos projects, building renovation, and building demolition activities that occur in facilities (institutional, commercial, public, or industrial), residential structures, installation, or building. The Asbestos Control Program regulates asbestos abatement activities that involve three or more square or linear feet of asbestos-containing material. In order to determine which requirements apply to a building owner or contractor of a renovation or demolition, an asbestos inspection is required. Prior to remodeling, repairing, or demolishing a home, a person should determine if the materials impacted by the project contain asbestos. The Asbestos Control Program maintains a list of accredited and approved asbestos inspectors and laboratories.

Federal regulations are governed by the EPA (Environmental Protection Agency) and OSHA (Occupatoinal Safety and Health Administration), while recommendations for safety are made by NIOSH (National Institute for Occupational Safety and Health). The EPA has proposed a concentration of 7 x 106 fibers/liter of drinking water for (>5um) and OSHA has set limits of 100,000 fibers (>5um) per m3 of workplace air for an 8hr shift and 40hr workweek. NIOSH has recommended that inhalation exposures do not exceed 100,000 fibers (>5um) per m3 of air. In 1989 EPA banned any new uses of asbestos.  

The EPA has established regulations that require schools to inspect for damaged asbestos and to eliminate or reduce the exposure by removing or sealing. EPA regulates asbestos release from factories and during building renovation and demolition.

Q:  Where can I find more asbestos-related resources?


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