[inglés] Miscellaneous amendments to 30 CFR Parts 55 - Health and safety standards: Metal and nonmetallic open pit mines; 56 - Health and safety standards: Sand, gravel and crushed stone operations; and 57 - Health and safety standards: Metal and nonmetallic underground mines. Jurisdicción Estados Unidos Ańo 1974 Publicado en inglés Título original / otro título [inglés] Miscellaneous amendments to 30 CFR Parts 55 - Health and safety standards: Metal and nonmetallic open pit mines; 56 - Health and safety standards: Sand, gravel and crushed stone operations; and 57 - Health and safety standards: Metal and nonmetallic underground mines. Título de revista periódica Federal Register Fuente [inglés] 1 july 1974, Vol.39, No.127, p.24316-24320. Descriptores [Principales] Estados Unidos, minas, polvos, pulverización, separación, selección [Secundarios] agentes de voladura, amianto, ley, lucha contra los polvos, prevención de las explosiones, respiradores, valores umbrales Categoría Industrias y ocupaciones Resumen [inglés] These amendments, dated 26 june 1974, became effective on 1 July 1974. They prescribe that exposure to airborne contaminants must not exceed the TLVs adopted by the ACGIH, and that the 8-h time-weighted average airborne concentration of asbestos dust to which workers are exposed must not exceed 5 fibres >5ľm in length per ml, as determined by the membrane filter method. Control of employee exposure must be preferably by prevention of contamination, removal by exhaust ventilation or by dilution with uncontaminated air. Other provisions concern respirators, blasting agents, avoidance of spark or flame in repairing premise used for storage of explosives, coupling of oxygen hoses to jet-piercing drills, electrical equipment, prevention of over-travel of man hoists, etc. CIS No. 75-209 Número de registro 22368