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Asbestos is a fibrous mineral found in metamorphic rock, a rock composed of several minerals compressed by time and movement of the earth over millions of years. The most common type of asbestos, chrysotile, is extracted from serpentine, a metamorphic rock that is common worldwide. Asbestos is separated from other minerals by crushing the rock and sifting to separate the various minerals by weight. Chrysotile asbestos has needle-like fibres that cling to anything they come into contact with including leaves, fabric and human tissue. Asbestos' carcinogenic properties have been documented beginning in the 1930s and today, the mineral, once prized for its insulating and fireproofing qualities, is used only in a chosen few applications like brake drums and gaskets. Most countries, including the United States, European Union and Australia, have outlawed its use in construction and closely regulate safety in manufacture and delivery of remaining allowed uses.
When the dangers of asbestos fibres were first verified by studies in the 1970s, governments began requiring retrofitting and removal of asbestos insulation, flooring and roofing materials. In 1989, the U.S. Environmental Protection Agency outlawed the use of the material but the prohibition was modified by a federal court three years later to remove prohibitions on certain uses where no practical substitute was available. Workers in asbestos manufacturing facilities were the first victims of environmental asbestos but they were not the last. Today, free asbestos is found in the atmosphere and water supply of most industrialised nations. In the 1990s, new guidelines defined what type and condition of asbestos should be removed. The Occupational Safety and Health Administration (OSHA) developed rules for safe removal. Although homeowners are allowed to remove asbestos from their own domicile or encapsulate it in a spray covering, most home and all business owners choose to hire professionals to diagnose and extract existing asbestos.
Asbestos is extracted in a sealed, high humidity environment. Negative air pressure is generated in large areas to insure that any airborne fibres flow back into the work area rather than floating out. Air may flow into the area but not out until it has been filtered through a sealed vacuum system. Workers must be trained in "Haz-Mat" asbestos protocols and wear protective clothing and masks that are donned before entering and discarded before leaving the work area. All material scheduled for removal is wet down to retard airborne dispersion. Although small amounts, like brake linings, are removed and sealed in a "glove bag", larger amounts are sealed in special containers or sealed wraps. All asbestos is deposited in a dedicated hazardous waste landfill or is recycled into silicate glass to be used in tiles and bricks. The expense of extraction makes it sensible to get an expert opinion from an OSHA-certified professional before tearing out intact materials.