Asbestos is a naturally occurring mineral, used by humans since ancient times but not extensively until the 1940s. After World War II and for the next 30 years, it was widely used as a construction material in schools and other public buildings. The United States Environmental Protection Agency (EPA) estimates that there are asbestos-containing materials in most of the primary and secondary schools as well as in most public and commercial buildings in the nation. It is estimated that 27 million Americans had significant occupational exposure to asbestos between 1940 and 1980. Asbestos has been popular because it is readily available, low in cost, and has very useful properties. It does not burn, conducts heat and electricity poorly, strengthens concrete products into which it is incorporated, and is resistant to chemical corrosion. It has been used in building materials as a thermal and electrical insulator and has been sprayed on steel beams in buildings for protection from heat in fires. Asbestos has also been used as an acoustical plaster. In 1984, an EPA survey found that approximately 66% of those buildings containing asbestos had damaged asbestos-containing materials in them. The EPA distinguishes between two types of asbestos damage. If the material, when dry, can be crumbled by hand pressure, it is called "friable." If not, it is called "non-friable." The friable form is much more likely to release dangerous fibers into the air. Fluffy, spray-applied asbestos fireproofing material is an example of friable asbestos. Vinyl-asbestos floor tile is an example of a non-friable material, although it too can release fibers when sanded, sawed, or aggressively disturbed.
Growing recognition that asbestos dust is a dangerous air pollutant has led to government regulation of its use and provisions for removal of asbestos and asbestos-containing products from dwellings, schools, and the workplace. In the United States, the Federal Government has taken steps to prevent unnecessary exposure to asbestos since the 1970s. Six different agencies have authority to regulate some aspect of asbestos use in the United States. The authorized agencies are the EPA, Occupational Safety and Health Administration (OSHA), Food and Drug Administration , Consumer Product Safety Commission, Department of Transportation , and the Mine Safety and Health Administration.
The EPA has authority to oversee use of asbestos in commerce and has developed standards controlling its handling and use. It administers the Asbestos Hazard Emergency Response Act (AHERA) of 1986 that regulates asbestos in schools. The Act prescribes management practices and abatement standards for both public and private schools, and it follows a 1979 rule that launched a technical assistance program to aid schools in efforts to identify asbestos-containing materials. AHERA requires schools to develop a management plan concerning their asbestos-containing materials. Schools must appoint an asbestos manager to be responsible for a number of activities, which include implementing a plan to manage asbestos-containing building materials and ensuring compliance with federal asbestos regulations. AHERA also requires local officials to carry out inspections to identify asbestos-containing materials in public and private elementary and secondary schools, and to comply with AHERA's record keeping requirements. The emphasis on asbestos abatement in schools arises from the recognition that children are especially vulnerable to a virulent form of lung cancer called mesothelioma caused by asbestos.
The EPA also administers the Asbestos School Hazard Abatement Reauthorization Act (ASHARA) of 1990 which requires that accredited personnel be used to work with asbestos in schools and in public and commercial buildings. The Act sets training requirements for asbestos professionals, contractors, and abatement workers. It is estimated that 733,000 public buildings in the United States (about 20% of the total) have some type of defective or deteriorating asbestos-containing material in them. Asbestos is frequently found in pipe and boiler insulation, caulking putties, joint compounds, linoleum, acoustical plaster, ceiling tiles, and other building components. ASHARA does not require owners of public and commercial buildings to conduct inspections for asbestos-containing materials, but it does require owners who opt for inspections to use accredited inspectors. To obtain accreditation, asbestos workers must take a 4-day, 32-hour EPA-approved training course covering topics such as potential health effects of asbestos exposure, the use of personal protective equipment, and up-to-date work practices. Detached single-family homes and residential apartment buildings of fewer than 10 units are not covered by the Act.
The EPA is also responsible for the 1989 Asbestos Ban and Phase out Rule that was partially overturned by a Federal Court in 1991. Originally, the ban applied to a wide variety of asbestos-containing products including roof coatings, floor tile, brake pads and linings, and pipeline wrap. Although these products and many others were removed from the ban, it still applies to all new uses of asbestos. The ban remains in effect for the sprayed-on asbestos fireproofing that has been prohibited since 1978.
Individual home owners may seek advice from local health officials concerning potential asbestos problems in or on their dwelling. State agencies often publish pamphlets or brochures that offer help in identifying and correcting problems. Common places to find asbestos in homes include wall, ceiling, and pipe insulation in structures built between 1930 and 1950, and in sheet vinyl, vinyl tile, and vinyl adhesive used in floor coverings. These materials are considered safe, and need not be removed unless they are damaged or disturbed. Wall and ceiling surfaces may contain troweledon or sprayed-on surface material containing asbestos. If the material is hard, firmly attached, and does not produce a powder or dust when hand pressure is applied, it is probably not hazardous. On the exterior of many older homes, a cement asbestos board called Transite™ has been used as sheet or lap siding and has sometimes been shaped to mimic wood shingles. This material, too, is considered safe unless it has been damaged or disturbed. Other asbestos-containing objects in the home include older electrical lamp socket collars, switch and receptacle boxes, fuse boxes, and old-fashioned "knob and tube" wiring. Asbestos is found in insulation blankets of older ovens, dishwashers, water heaters, and freezers. These items need not be removed if they are intact and not damaged.
There is no safe and reliable way for an untrained individual to identify asbestos except to have it analyzed by a competent testing laboratory. In taking a sample for laboratory analysis, it is important that one not release fibers into the air or get them into one's clothes. To avoid this, it is often helpful to spray the material with a fine mist of water before sampling. The material should not be disturbed more than necessary, and the sample for testing should be enclosed in a sealed plastic or glass vial. If asbestos-containing materials must be removed, they should not be placed with other household trash. Local health officials should be contacted for instructions on safe disposal.
Most public buildings with asbestos-containing materials do not pose an immediate risk to the occupants. As long as the asbestos is sealed and not releasing fibers, there is no health threat. Since asbestos is easily disturbed during building alterations, routine maintenance, and even normal use, it is wise to take precautions to control or eliminate exposure. When asbestos-containing objects are identified, removal, encapsulation, and containment may be used to protect occupants. If the objects are damaged or in poor condition, they should be removed. Proper removal techniques must be strictly followed to avoid spreading contamination. Encapsulation is accomplished by sealing objects with an approved chemical sealant. Containment can be accomplished by constructing suitable physical barriers around the objects to contain any fibers that may be released. Air monitoring and inspection of buildings with asbestos-containing material should be performed regularly to be sure that fiber releases have not occurred. Maintenance and operations crews should be notified of an asbestos threat in their building, and they should be taught proper precautions to avoid accidental disturbance.
The Occupational Safety and Health Administration (OSHA), under the jurisdiction of the United States Department of Labor, is charged with protection of worker safety on the job. OSHA estimates that 1.3 million employees in construction and general industry face significant asbestos exposure in the workplace. Greatest exposure occurs in the construction industry, especially while removing asbestos during renovation or demolition. Workers are also apt to be exposed during the manufacture of asbestos products and during automobile brake and clutch repair work. OSHA has set standards for maximum exposure limits, protective clothing, exposure monitoring, hygiene facilities and practices, warning signs, labeling, record keeping, medical exams, and other aspects of the workplace. Workplace exposure for workers in general industry and construction must be limited to 0.2 asbestos fibers per 0.061 cu in. of air (0.2 f/cc), averaged over an eight-hour shift, or 1 fiber per 0.3 cu in. of air (1 f/5cc) over a standard 40-hour work week.
[Douglas C. Pratt ]
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U.S. Environmental Protection Agency. Asbestos in the Home: A Homeowner's Guide. Washington, D.C., 1992.
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