The Obama administration on Thursday will propose new rules designed to eliminate black lung, a scourge affecting the nation's miners.
The disease, more technically known as coal worker's pneumoconiosis ("dusty lung"), is caused by inhaling coal dust over long periods of time.
The big question about Thursday's announcement: Will the agency propose to reduce workers' permissible exposure limit (PEL) to coal dust? Or will it simply take steps to limit miners' exposure to the dust?
The difference is nuanced but significant.
The mining industry has argued the current PEL — which, since 1972, has been set at 2 milligrams of dust per cubic meter of air over an eight-hour shift — is appropriate, but just not very well enforced. In their version of the tale, any occurrence of black lung is the result of companies simply not complying with the current limits.
More than 10,000 miners have died from the disease in the past 10 years.
Many health and mine-safety experts, however, tell a different story. They say the current PEL is too high and doesn't go far enough to protect the nation's miners. If the Labor Department simply takes steps to enforce the PEL without lowering it, they warn, black lung will remain an enormous problem.
"Even if every single company were complying with the standard, you would still have the disease," Celeste Monforton, a former mine-safety official in the Labor Department who's now a public health professor at George Washington University, said Wednesday. "The science tells us that 2 [mg/m3] is not protective."
Bolstering that argument, the National Institute for Occupational Safety and Health (NIOSH) issued a report 15 years ago that found occurrences of black lung in miners exposed to lesser levels of coal dust.
NIOSH recommended the PEL be reduced to 1 mg/m3 over a 10-hour shift. Even at that lower level, the agency warned in a more recent report, some miners would get black lung.
"Even at the 1 mg/m3 coal mine dust exposure limit recommended by the CCD, some occupational effect on ventilatory function is expected," NIOSH said.
Faced with opposition from the coal industry — not to mention the powerful lawmakers of coal country — the proposal was never adopted.
Meanwhile, the cases of black lung in America are on the rise. Last December, NIOSH reported that about 9 percent of miners with at least 25 years experience in the mines tested positive for black lung between 2005 and 2006 — more than double the 4-percent rate of a decade earlier.
Monforton said it remains unclear why the problem seems to be getting worse. It could be that more miners are being diagnosed simply because more miners are being screened for the disease, she said. Or it might be that more powerful mining equipment is kicking up more coal dust underground; or more miners are working longer shifts; or the coal mines contain more silica — a substance found in quartz that's even more harmful to lungs than coal dust — than previously thought.
"All the more reason," Monforton said, "to adopt new standards based on science."
We'll know tomorrow if the administration takes that advice.