Noise Exposure and Hearing Conservation in U.S. Coal Mines—A Surveillance Report

Abstract

This study examines the patterns and trends in noise exposure documented in data collected by Mine Safety and Health Administration inspectors at U.S. coal mines from 1987 through 2004. During this period, MSHA issued a new regulation on occupational noise exposure that changed the regulatory requirements and enforcement policies. The data were examined to identify potential impacts from these changes. The overall annual median noise dose declined 67% for surface coal mining and 24% for underground coal mining, and the reduction in each group accelerated after promulgation of the new noise rule. However, not all mining occupations experienced a decrease. The exposure reduction was accompanied by an increase of shift length as represented by dosimeter sample duration. For coal miners exposed above the permissible exposure level, use of hearing protection devices increased from 61% to 89% during this period. Participation of miners exposed at or above the action level in hearing conservation programs rapidly reached 86% following the effective date of the noise rule. Based on inspection data, the occupational noise regulation appears to be having a strong positive impact on hearing conservation by reducing exposures and increasing the use of hearing protection devices and medical surveillance. However, the increase in shift duration and resulting reduction in recovery time may mitigate the gains somewhat.

Interventions to prevent occupational noise-induced hearing loss: A Cochrane systematic review

“…Two studies used a randomized design (Berg et al, 2009; Seixas et al, 2011) and two studies used an interrupted time-series (ITS) design (Joy & Middendorf, 2007; Rabinowitz et al, 2011). All remaining studies used a form of controlled before-after design.…”

“…The legislation evaluation study (Joy, 2007) was carried out in coal mines and the administrative control intervention study (Seixas et al, 2011) in construction sites in the USA.…”

“…For time-series, data from the original papers (Joy & Middendorf, 2007) were extracted or additional data were obtained from the authors (Rabinowitz et al, 2011) and re-analysed according to the recommended methods for analysis of ITS designs for inclusion in systematic reviews (Ramsay et al, 2003). This resulted in an effect estimate for an immediate change in noise levels after the intervention and an estimate for the change in trend over time after the intervention.…”

Insertion Loss of Noise Barriers on an Aboveground, Full-Scale Model Longwall Coal Mining Shearer

“…This model was chosen due to the extremes of the operating environment and the fact that shearer operators are routinely exposed to hazardous noise levels at 151% of the allowable daily dose. (8) The total room absorption (TA) of the full-scale longwall model was measured using a known sound power source to determine how reflective the room would be. The greater the contribution of reflected path noise over direct path noise, the less insertion loss would be expected from the barrier.…”

“…(8) The underground IL estimated that the simple barrier reduced noise at the operators' positions by 1.7 to 2.5 dBA. The less practical full barrier resulted in a greater estimated reduction of 3.7 to 7.3 dBA.…”