Respirable coal mine dust at surface mines, United States, 1982–2017

Abstract

Background: Exposure to respirable coal mine dust can cause pneumoconiosis, an irreversible lung disease that can be debilitating. The mass concentration and quartz mass percent of respirable coal mine dust samples (annually, by occupation, by geographic region) from surface coal mines and surface facilities at U.S. underground mines during 1982-2017 were summarized.Methods: Mine Safety and Health Administration (MSHA) collected and analyzed data for respirable dust and a subset of the samples were analyzed for quartz content. We calculated the respirable dust and quartz concentration geometric mean, arithmetic mean, and percent of samples exceeding the respirable dust permissible exposure limit (PEL) of 2.0 mg/m3, and the average percent of quartz content in samples. Results:The geometric mean for 288 705 respirable dust samples was 0.17 mg/m 3 with 1.6% of the samples exceeding the 2.0 mg/m 3 PEL. Occupation-specific geometric means for respirable dust in active mining areas were highest among drillers. The geometric mean for respirable dust was higher in central Appalachia compared to the rest of the U.S. The geometric mean for respirable quartz including 54 040 samples was 0.02 mg/m 3 with 15.3% of these samples exceeding the applicable standard (PEL or reduced PEL). Occupation-specific geometric means for respirable quartz were highest among drillers.Conclusion: Higher concentrations of respirable dust or quartz in specific coal mining occupations, notably drilling occupations, and in certain U.S. regions, underscores the need for continued surveillance to identify workers at higher risk for pneumoconiosis.

Assessment of pneumoconiosis in surface coal miners after implementation of a national radiographic surveillance program, United States, 2014–2019

“…The findings from the latest assessment of the respiratory health of actively working US surface coal miners are remarkably similar to findings from assessments conducted in decades past. In addition to the current health findings, our recent analysis of 36 years of compliance sampling data 17 led us to the same paradoxical conclusion that Parobeck and Tomb 12 reported in 1974—the majority of dust samples collected at the US surface mines are at or below the applicable standard even though medical surveillance findings are consistent with surface miners in certain occupations being overexposed to respirable dust including respirable crystalline silica. Taken as a whole, these surveillance findings, recent clinic‐based investigations (which identified surface miners with advanced disease including PMF) and the MSHA inspector‐collected compliance sampling findings are consistent with pneumoconiosis in surface coal miners being caused by overexposure to respirable dust containing quartz (a type of respirable crystalline silica) 1,4,17 …”

“…In a large sample of the US surface coal miners, 109 (1.6%) had pneumoconiosis and there was significantly more disease in Central Appalachia compared with the rest of the United States, even after adjusting for tenure. The higher prevalence of the disease among surface miners in Central Appalachia corresponds to sampling data which shows that surface coal mines in this region consistently have higher respirable dust, respirable quartz, and percent quartz in their samples when compared with the rest of the United States 17 . Miners who had worked as a driller or blaster had a significantly higher prevalence of disease compared with those who had never held these jobs, which also corresponds to the surface mine sampling data and previous studies identifying surface miners with PMF as primarily having worked as drillers or blasters 5,6,10,10,17 …”

“…Increasing evidence in the form of case reports, clinic‐based investigations, and targeted surveillance efforts has revealed that the burden of pneumoconiosis in modern US coal miners is not isolated to underground workers but also occurs in surface miners 4–6 . Both underground and surface coal miners can be exposed to excessive amounts of respirable coal mine dust which, with sufficient exposure, causes pneumoconiosis 7 . Coal mine dust is composed of coal dust and other mineral dust, such as respirable crystalline silica dust from rock containing quartz.…”

Respirable Coal Mine Dust: A Review of Respiratory Deposition, Regulations, and Characterization

“…The risk of CWP prevalence is associated with RCMD composition, concentration, and exposure duration [4,22,109]. Doney et al [74,110] investigated the mass concentrations of RCMD and RCS using the MSHA database between 1982 and 2017. The results of 681,497 RCMD and 210,944 respirable silica dust (RCS) samples in underground mines showed an average of 0.55 mg/m 3 and 0.038 mg/m 3 for RCMD and RCS concentrations, respectively.…”

“…The number of RCMD samples exceeding the PEL in underground mines was three times greater than surface mines. The geometric mean of RCMD for different occupational group in underground coal mines was reported as longwall worker (1.02 mg/m 3 ), continuous miner operator and helper (0.73 mg/m 3 ), cutting machine operator and helper (0.67 mg/m 3 ), auger (0.65 mg/m 3 ), roof bolter (0.59 mg/m 3 ), stopping builder/ventilation man/mason (0.57 mg/m 3 ), blaster and helper (0.50 mg/m 3 ), coal drill operator and helper (0.48 mg/m 3 ), beltman/conveyor man/belt cleaner (0.46 mg/m 3 ), and loading machine operator (0.44 mg/m 3 ) [74,110]. * Data obtained from [99].…”