Best practices for dust control in coal mining. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 2010-110, Pittsburgh, PA: National Institute for Occupational Safety and health, 2010 Jan; :65-76
Overexposure to airborne respirable crystalline silica dust (referred to here as "silica dust") can cause silicosis, a serious and potentially fatal lung disease. Mining continues to have some of the highest incidences of worker-related silicosis, and the mining machine operator is the occupation most commonly associated with the disease [NIOSH 2003]. In particular, some of the most severe cases of silicosis have been observed in surface mine rock drillers [NIOSH 1992]. A voluntary surface coal miner lung screening study conducted in Pennsylvania in 1996 found that silicosis was directly related to age and years of drilling experience [CDC 2000]. U.S. mine workers continue to be at risk of exposure to excessive levels of silica dust. The percentage of Mine Safety and Health Administration (MSHA) dust samples during 2004-2008 that exceeded the applicable or reduced respirable dust standard because of the presence of silica were: 12% for sand and gravel mines, 13% for stone mines, 18% for nonmetal mines, 21% for metal operations, and 11% for coal mines [MSHA 2009]. At surface mining operations, occupations most frequently exceeding the applicable respirable dust standard are usually operators of mechanized equipment such as drills, bulldozers, scrapers, front-end loaders, haul trucks, and crushers. This chapter summarizes the current state of the art of dust controls for surface mines. Surface mining operations present dynamic and highly variable silica dust sources. Most of the dust generated at surface mines is produced by mobile earth-moving equipment such as drills, bulldozers, trucks, and front-end loaders excavating silica-bearing rock and minerals. Four practical areas of engineering controls to mitigate surface mine worker exposure to all airborne dusts, including silica, are drill dust collection systems, enclosed cab filtration systems, controlling dust on unpaved haulage roads, and controlling dust at the primary hopper dump. Many surface mine dust control problems can be visually observed and diagnosed. Visible airborne dust emissions generated from a particular surface mine process usually indicate that respirable silica dust can be present and potentially become a worker exposure problem. Visual dust emissions affecting nearby workers indicates that an engineering control is needed or an existing control needs maintenance. Investigating possible causes of visual dust emissions when using an engineering control often can uncover the reason for its poor dust control effectiveness. Frequent visual inspections of engineering control systems can identify needed maintenance to optimize their dust control effectiveness. Area dust sampling should be conducted, in conjunction with personal sampling, to quantify potential dust sources and examine their contribution to the worker dust exposure problem.
Mining-industry; Silicosis; Respirable-dust; Silica-dusts; Lung-disease; Equipment-operators; Machine-operators; Surface-mining; Coal-mining; Exposure-levels; Dust-sampling; Standards; Occupational-exposure; Dust-control; Control-methods; Engineering-controls; Dust-collection; Control-systems; Filtration; Dust-exposure