Worker exposures to dust and noise were surveyed at 22 gravel crushing and hot mix facilities (SIC-5211) in Idaho, New Mexico and Oregon during 1968 to 1969. The companies employed a total of 118 workers. Free silica (7631869) concentrations ranged from 0.2 to 59 percent. Personal air samples contained up to 108 milligrams per cubic meter of free silica. Noise levels were 90 to 105 decibels, and the maximum daily exposure was 1 to 8 hours. Forty three percent of the workers at the dry run crushers and 67 percent of the workers in the hot mix areas that did not have emission controls were exposed to twice the threshold limit values of silica and to excessive amounts of noise. The author recommends that hot mix and crusher facility workers wear ear muffs or plugs, and that dry crusher and hot mix facility workers wear approved free silica dust masks. Workers should be given periodic chest X-ray and audiometric examinations. Crusher operations should be water washed, and all heavy equipment and dozer operation workers should be required to wear ear protective devices.
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