PURPOSE:  To establish representative noise exposure profiles for the various mining occupations, equipment noise levels, and characterize the exposure/source relationship.

RESEARCH SUMMARY:  Noise-induced hearing loss (NIHL) is recognized by NIOSH in the NORA document as the most common occupational disease in the United States. Despite the progress achieved over the last 2 decades, overexposure to noise in the mining workplace remains a serious problem for mine workers. Every day, 80% of the Nation’s miners go to work in an environment where the time-weighted average (TWA) noise level exceeds 85 dB(A); even worse, 25% of the miners are exposed to a TWA noise level that exceeds 90 dB(A). Several studies have shown that by age 50, 90% of miners have a hearing impairment. Recent noise exposure data collected in the coal industry during project surveys indicate that nearly 50% of workers were exposed to noise levels above 90 dB(A), with some exposures nearly 6 times the permissible exposure level. Clearly, a need exists for research to ensure that the hearing of miners will be preserved.

Surveillance is seen as one of the fundamental keys to this effort. The collection of baseline information that will provide a current and improved characterization of worker noise exposure patterns and mining noise sources is essential to develop effective intervention strategies for preventing hearing loss. The baseline line data will consist of worker noise dose, task observations to relate source to dose, and equipment noise profiles. It is anticipated that 5 to 10 mines and plants will be surveyed each year, with 45 to 50 mines and plants total surveyed by project end in 2007. The mining sectors investigated will include coal, stone, and sand and gravel.

Results to date indicate that upwards of 40% of all workers monitored were subject to noise exposures above 90 dB(A) TWA8. In the underground coal mines, the percentage is nearly twice as high for workers directly involved with the extraction of coal at the mine face. The data also reveals that the underground coal extraction equipment is among the noisiest equipment used in mining and is the primary contributors to worker overexposures.

The expected outputs of this research are updated data bases of equipment noise and worker noise exposures in all sectors of mining. The outcomes include a more comprehensive understanding of the noise environment in the mining industry and a more effective selection and application of both engineering and administrative controls for reducing worker noise exposures.