Appalachian surface coal miners are consistently overexposed to toxic silica dust, according to new research from the National Institute for Occupational Safety and Health, and surface mine dust contains more silica than does dust in underground coal mines.
The research released Tuesday is the first to specifically analyze long-term data on exposure to toxic silica dust for workers at surface mines. The work reveals that while attention has been trained on a surge in disease among underground coal miners, surface miners are similarly at risk of contracting coal worker’s pneumoconiosis, or black lung disease.
Black lung disease has been identified in coal miners in every coal-mining state at both surface and underground mines. NIOSH researchers were specifically interested in surface miners’ exposure because those mines produce the most coal and, in 2017, twice as many miners worked at surface mines compared to underground mines.
Researchers analyzed 54,040 coal dust samples taken on surface mines between 1982 and 2017 to determine the percent of that coal dust that was silica, and found that the level of silica was above the permissible limit in 15 percent of those samples. Silica dust comes from quartz in the rock layers near coal seams, and it is significantly more harmful to lung tissue than coal dust alone.
“The exposure to coal mine dust declined over time,” said lead researcher and industrial hygienist Brent Doney. “However … when you look at the percentage of silica that was in those samples, that didn’t drop.”
After decades of successful reduction in black lung disease through safety controls in coal mines, black lung disease has been on the rise among coal miners for the last two decades. Central Appalachia has seen a marked increase in the most severe form of black lung, known as progressive massive fibrosis. A recent investigation from NPR and PBS Frontline found that federal regulators and the mining industry knew that exposure to silica dust was a major factor contributing to the surge in disease but failed to act to protect miners’ health.
The surge in disease is putting strain on the already-indebted federal Black Lung Disability Trust Fund, and as younger miners become disabled due to black lung, the strain on Appalachian mining communities continues to grow.
“Unfortunately, I’m not sure this is a particularly novel finding,” NIOSH epidemiologist Scott Laney said. “The evidence is very clear. We know that silica and mine dust are toxic, and we have the technology to suppress it, and yet coal miners are still exposed to way too much of it. So from a public health perspective, there’s ample evidence to suggest that further safeguards are necessary.”
The federal Mine Safety and Health Administration, which regulates coal mining, issued in August a request for information to determine whether additional regulation of silica was necessary, and if so, how best to proceed. Some critics of the administration argued the move was too little given what is already known about silica’s role in disease.