thinner coal seams in central Appalachia are likely to blame for spikes in complicated black lung. The thickest seams are mostly gone. The thin seams that remain have coal embedded in rock, and that rock contains quartz. Cutting quartz and coal together results in mine dust that includes silica, which is especially toxic in lung tissue. Stanley worked in so much dust he labeled his mining machine the dust dragon.
"They kept getting less coal and more rock. So you're cutting 19 inches of coal, you're cutting 50-60 inches of rock," Stanley recalls. "And the more rock you cut the more dust you're going to eat."
There's also the practice of slope mining, where crews cut solid rock to reach coal seams. Burnham did that in Kentucky for six straight months, working 14 16-hour shifts at one point.
It was "pure rock dust," he says. "I had my respirators on and you'd actually have to remove it to help take a breath every once in a while because the dust packed so much around your filters you couldn't get no air in."
Protective masks are among the controls that are supposed to prevent inhalation of coal and silica dust. Robust ventilation in mines is supposed to sweep dust away. Water sprays are used to tamp down dust.
Kentucky miner Barney Stanton says those things didn't always work, even when most of the companies he worked for provided proper safety gear.
"It's hard to wear a mask and do a physical job," he says. "Just trying to do your job, you breathe so hard the dust will come in around the mask."
Stanton has been diagnosed with the most serious stage of PMF and is awaiting a lung transplant.