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MINER Center tracks black lung disease surge

Kirsten Almberg photo.

Public health researchers and clinicians have been building their understanding of the symptoms and risks of black lung disease for well over a century. Yet despite this long history, current and former coal miners are experiencing an historic rise in black lung disease cases and incidences of severe disease.

With colleagues at SPH’s Mining Education and Research Center, Kirsten Almberg, (PhD ‘16, MS ’12), research assistant professor of environmental and occupational health sciences, is digging into why black lung cases are on the rise. Research findings point to increased exposure to silica dust as a possible cause.

“Coal mine dust is a mixture of components, and a lot of those components can be quite toxic, but principle among those is silica,” Almberg said. “Much of the ‘easy’, or thin-seamed, coal has been mined out in the U.S., and the trend of extracting remaining coal from thinner, or otherwise hard to reach seams means more grinding of the rock above and below coal seams, leading to higher silica concentrations in the dust these miners are breathing.”

In a study of former coal miners from across the U.S. in 2020-21, Almberg and fellow researchers found miners in Central Appalachia – Kentucky, Virginia and West Virginia – are bearing the brunt of the increase in coal mine dust lung disease. Former miners in this region had significantly lower lung function compared to miners from the rest of the nation and these miners also experienced higher rates of black lung disease, including three times higher rates of progressive massive fibrosis, the most severe form of black lung disease.

Another study aimed to characterize mortality among coal miners. Examining more than 230,000 miners from 1979-2017, Almberg and co-investigators found significantly higher rates of death from pneumoconiosis and chronic obstructive pulmonary disease among miners, as compared with their counterparts in the general population. These disparities in mortality were highest in the most recent birth cohorts and among Central Appalachian miners.

The silica exposure believed to be driving these trends may have numerous causes. The increase in mechanization of mining, with more powerful machinery to pulverize rock and coal, generates smaller particles that travel deeper into the lungs. Almberg also cites the decline in unionization, which has decreased miners’ ability to bargain for safer working conditions.

Almberg says the Mining Safety and Health Administration should issue a separate rule for regulating silica dust, which currently does not exist despite standards for total respirable dust in mining operations. The Occupational Safety and Health Administration has regulated silica in other workplaces since 2018.

“Coal mine dust lung disease has one cause – over-exposure to coal mine dust,” Almberg said. “We know the causes, we know the public health implications, so the question becomes, why does this persist?”.