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Asbestos |
Respirable Particulates (PM2.5) |
Temperature | Relative Humidity | Carbon Dioxide | Carbon Monoxide | |
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Crystalline silica is found in materials such as concrete, masonry and
rock. When these materials are made into a fine dust and suspended in the
air, inhaling these fine particles can produce lung damage. Diseases
associated with the inhalation of silica-containing dusts include
silicosis, chronic airways obstruction and bronchitis, tuberculosis, and
lung cancer. The International Agency for Research on Cancer (IARC) has
identified silica as a potential human carcinogen.
Silicosis, a scarring and hardening of lung tissue, can result when particles of crystalline silica are inhaled and become embedded in the lung. The disease can be progressively debilitating and fatal. Silicosis usually develops only after long term exposures to high levels of silica dust, as may occur among construction workers and miners. However, exposure to materials that contain only small amounts of crystalline silica may be hazardous if they are disturbed in ways that produce high dust concentrations. Silicosis is normally not apparent until 20 years or more after the first exposure to silica has occurred. The rate at which silicosis progresses is related to the length and level of exposure to silica. The disease may progress even after exposure has stopped. There is no known medical treatment to reverse silicosis. Therefore, because prevention of exposure is the best method of protection, the Occupational Safety and Health Administration (OSHA) requires dust to be controlled whenever possible.
The National Institute for Occupational Safety and Health has a recommended
(industrial) exposure limit to silica of .05 /mmg/m3 (milligrams silica per
cubic meter of air).
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