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; :17-39
Medical studies have shown that prolonged exposure to excessive levels of respirable coal dust can lead to coal workers' pneumoconiosis (CWP), progressive massive fibrosis, and chronic obstructive pulmonary disease. These lung diseases are irreversible and can be debilitating, progressive, and fatal. CWP contributed to the deaths of 10,406 U.S. miners during 1995-2004 [NIOSH 2008]. Pneumoconiosis continues to be a very serious health threat to underground coal mine workers. Historically, longwall operations have had difficulty in maintaining consistent compliance with the federal dust standard of 2.0 mg/m3. During 2004-2008, mine operators and MSHA inspectors collected 6,600 and 1,321 valid compliance samples, respectively, from longwall designated occupations or high-risk occupations. These dust samples showed that 719 (11%) of the mine operator samples and 144 (11%) of the MSHA samples exceeded 2.1 mg/m3 [Niewiadomski 2009]. In addition, MSHA inspector sampling results from 2004-2008 show that longwall face workers were exposed to elevated levels of respirable silica dust. For MSHA occupation codes 044 (tail-side shearer operator) and 041 (jack setter) that were on reduced dust standards due to silica levels above 5%, 31% and 21% of the samples, respectively, exceeded the reduced standard [MSHA 2009]. The continued occurrence of CWP in underground coal mine workers and the magnitude of respirable dust overexposures in longwall mining occupations point to the need for improved dust control technology on longwalls. Longwall mining equipment and operational practices have improved dramatically since the early 1980s. In 2007, longwall mines accounted for 50% of U.S. underground coal production. Overall production from U.S. longwall mines peaked in 2004 and decreased by about 10% in 2007 with over 176 million tons mined [EIA 2009]. These production rates continue to challenge dust control efforts of the industry. Longwall workers can be exposed to harmful respirable dust from multiple dust generation sources, including the intake entry, belt entry, stageloader/crusher, shearer, and shield advance. This chapter discusses dust control technologies that are available to reduce dust liberated from each of these sources. Alternate controls that have the potential to provide additional dust reductions but currently not in use will also be discussed.