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Asbestos is a name given to a group of naturally occurring fibrous minerals. Asbestos has been heavily used in commercial and industrial application due to its unique properties of being resistant to abrasion, inert to acid and alkaline solutions, and stable at high temperatures.
Asbestos fibers are woven together or incorporated within other materials to create many products – an estimated 3,000 products contain asbestos. The building and construction industry used asbestos for strengthening cement and plastics. Also, asbestos was used for heat insulation, fire proofing, and sound absorption. The ship building industry used asbestos to insulate steam pipes, boilers, hot water pipes, and nuclear reactors in ships. Because of it's good resistance to friction and durability, asbestos is often used in brake shoes and clutch pads in cars, trucks, and airplanes.
Asbestos containing materials can be classified into one of three types:
Asbestos is a hazardous material when it becomes friable – meaning that asbestos is easily crumbled and reduced to powder by hand pressure, such as when it is disturbed or damaged. When asbestos is damaged or disturbed it releases fibers into the air. Airborne asbestos fibers are microscopic, odorless, and tasteless. Because asbestos fibers are small and light, they can be suspended in the air for long periods. People who live or work near asbestos related operations have a high chance of inhaling asbestos fibers that have been released into the air by work activities.
Once inhaled, the small, inert asbestos fibers can easily penetrate the body's defenses. They are deposited and retained in the airways and tissues of the lungs. In the alveoli, the location of gas exchange, asbestos causes the development of scar tissue - asbestosis. This thickening of the alveoli wall reduces the amount of oxygen available to the body leading to shortness of breath and chest pains. Asbestos is a known carcinogen that can cause lung and gastrointestinal cancers. Mesothelioma, a rare form of cancer affecting the outer membrane of the lung, heart, and abdominal cavity, is directly caused by asbestos exposure.
In 1988, the Environmental Protection Agency (EPA) of the United States government published a survey investigating the presence of asbestos in public and commercial buildings. Looking at 3.6-million buildings, the EPA found:
These results show a significant amount of buildings in the nation contains asbestos. In many cases, buildings had asbestos at varying levels of damage, meaning the presence of a potential hazard. Because of the dangers associated with friable asbestos, appropriate actions are required to reduce this risk. One of the most popular actions is the outright removal of asbestos. IN ALL CASES, AN ACCREDITED PROFESSIONAL SHOULD CONDUCT ASBESTOS REMOVAL.
They are four basic methods available for the safe removal or stripping of asbestos insulation, coatings and insulation boards. These are
1) Dry stripping – Is the most common method. However, removing asbestos in a dry state without using any water will produce higher dust levels than other methods. In fact, regulatory authorities do not recommend this asbestos removal method.
2) Controlled wet stripping - Involves the use of wetting fluids which are injected under pressure through needles into the lagging material. This softens the insulation matrix, breaking down the binding agents and controlling the fiber release. The insulation is cut away in clean sections and transferred to the disposal system. This is probably the safest way of removing asbestos since when properly saturated; the asbestos fiber release is very low.
3) High pressure water jetting - Is a specialized and potentially highly dangerous process usually used in large-scale operations, where access to the asbestos containing materials are difficult. It should only be used for removing stubborn patches of asbestos where other methods have failed.
4) Air management for hot stripping - This method can be used for hot stripping and comprises a high velocity airflow that directs the asbestos fibers to a filtered exhaust at the end of a specially designed enclosure. While the asbestos-containing insulation is cut and removed, it is sprayed to dampen the fiber release. Any residue remaining is cleaned using shadow vacuum techniques. Heat stress is greatly reduced due to the air movement and is further curbed by positioning reusable loose insulation quilts over exposed hot pipe work.