PURPOSE:  To determine the significance of cutting noise relative to the noise exposure of continuous mining machine operators.

RESEARCH SUMMARY:  Noise-induced hearing loss is (NIHL) is the most common occupational disease in the country. Despite 25 years of regulation, a recent NIOSH study showed that at age 51 approximately 90% of coal miners and 49% of metal/non-metal miners had a hearing impairment whereas only 10% of the non-occupational-noise exposed population had a hearing impairment. MSHA Coal Noise Data collected from 2000 to 2002 shows that 65% of the workers who were overexposed to noise operated one of seven types of equipment. Of these seven types of machines, continuous mining machines had the most noise overexposures, accounting for 35% of all noise overexposures.

The noise generated by a continuous mining machine is primarily due to three sources: the conveyor, the dust scrubber, and the cutting drum. Prior NIOSH projects have developed noise controls to reduce the sound levels generated by the conveyor and dust scrubber on continuous mining machines. However, the noise associated with cutting coal has not been addressed. This effort will focus on determining the significance of coal cutting noise to the noise exposure of continuous mining machine operators. The hypothesis is that cutting coal is a major contributor to the operator’s noise exposure. Sound levels near the continuous mining machine operator will be measured in mines while cutting and conveying coal. These sound levels will be analyzed to determine the worker noise exposure associated with each process.

NIOSH will determine if cutting noise is a significant contributor to the operator’s noise exposure. If so then candidate engineering control concepts would be evaluated and the promising concepts will be recommended for development and implementation.

Upon completion of this one year pilot study, the results will be published in a peer-reviewed journal and presented at the appropriate mining conferences. The results of the project will provide a direction for the development of engineering noise controls to reduce continuous mining machine operator noise exposure. If cutting noise is found to be significant, noise controls must be developed to reduce the sound levels generated by cutting coal. However, if cutting noise is found to be insignificant, the future direction of noise control development for continuous mining machines would then be focused on additional noise controls to address conveyor noise.