Eric A. Lutz, Rustin J. Reed, Dylan Turner, Sally R. Littau and Vivien Lee, Mining Safety and Health Program, Environmental and Occupational Health, Division of Community, Environment, and Policy, Mel & Enid Zuckerman College of Public Health, University of Arizona, Tucson, Arizona; Chengcheng Hu, Department of Biostatistics, Division of Epidemiology and Biostatistics, Mel & Enid Zuckerman College of Public Health

Noise exposure and hearing loss in the mining industry continue to be a major problem, despite advances in noise-control technologies. This study evaluated the effectiveness of engineering, administrative and personal noise controls, using both traditional and in-ear dosimetry by job task, work shift and five types of earplug. The noise exposures of 22 miners performing deep shaft-sinking tasks were evaluated during 56 rotating shifts in an underground mine. Miners were earplug-insertion-trained, earplug-fit-tested and monitored utilizing traditional and in-ear dosimetry. The mean TWA₈ noise exposure via traditional dosimetry was 90.1 ± 8.2 dBA, while the mean in-ear TWA₈ was 79.6 ± 13.8 dBA. The latter was significantly lower (p < 0.05) than the Mine Safety and Health Administration (MSHA) personal-exposure limit (PEL) of 90 dBA. Dosimetry mean TWA₈ noise exposures for bench blowing (103.5 ± 0.9 dBA), jumbo-drill operation (103.0 ± 0.8 dBA), and mucking tasks (99.6 ± 4.7 dBA) were significantly higher (p < 0.05) than other tasks. For bench blowing, cable pulling, grinding and jumbo-drill-operation tasks, the mean in-ear TWA₈ was greater than 85 dBA. Those working swing shift had a significantly higher (p < 0.001) mean TWA₈ noise exposure (95.4 ± 7.3 dBA) than those working day shift. For per cent difference between traditional vs. in-ear dosimetry, there was no significant difference among types of earplug used. Reflective of occupational hearing-loss rate trends across the mining industry, this study found that, despite existing engineering and administrative controls, noise-exposure levels exceeded regulatory limits, while the addition of personal hearing protection limited excessive exposures.

J Occup Environ Hygiene, Volume 12, Issue 5, pages 287-293. Correspondence to: Eric A. Lutz, director, Mining Safety and Health Program, Mel & Enid Zuckerman College of Public Health, University of Arizona, 1656 E. Mabel Street, #113, Tucson, Arizona 85724; email: ealutz@email.arizona.edu.