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U.S. Department of Labor Mine Safety and Health Administration Protecting Miners' Safety and Health Since 1978 |
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§ 71.702 Asbestos standard. (a) Definitions. Asbestos is a generic term for a number of hydrated silicates that, when crushed or processed, separate into flexible fibers made up of fibrils. As used in this part-- Asbestos means chrysotile, cummingtonite-grunerite asbestos (amosite), crocidolite, anthophylite asbestos, tremolite asbestos, and actinolite asbestos. Fiber means a particle longer than 5 micrometers ([mu]m) with a length-to-diameter ratio of at least 3-to-1. (b) Permissible Exposure Limits (PELs)-- (1) Full-shift limit. A miner's personal exposure to asbestos shall not exceed an 8-hour time- weighted average full-shift airborne concentration of 0.1 fiber per cubic centimeter of air (f/cc). (2) Excursion limit. No miner shall be exposed at any time to airborne concentrations of asbestos in excess of 1 fiber per cubic centimeter of air (f/cc) as averaged over a sampling period of 30 minutes. (c) Measurement of airborne fiber concentration. Fiber concentration shall be determined by phase contrast microscopy using a method statistically equivalent to the OSHA Reference Method in OSHA's asbestos standard found in 29 CFR 1910.1001, Appendix A. |
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