Nearly all air samples collected from coal mines in August and September complied with stricter new limits on dust even though the industry had argued it would have trouble meeting the standards, federal regulators announced.
Of the 4,255 valid samples collected by federal inspectors in the first 60 days of the new rule, only 20 — less than 0.5 percent — contained enough dust to warrant a violation, the U.S. Mine Safety and Health Administration said in a news release.
Coal operators also are required to take samples.
Of the 3,201 samples submitted by coal companies in August and September, only 42, or 1.3 percent, were over the limit, MSHA said.
"These samples were all generated under the new, more rigid standard," MSHA chief Joe Main said in a news release. "And the results clearly show that mine operators are able to comply with the rule. That's good news for the health of all coal miners and our efforts to end black-lung disease."
MSHA has done extensive training to help companies sample for dust under the new rules.
Operators are required to control the level of breathable dust, which can cause black lung, in coal mines through the use of ventilation and other measures.
Black lung, an incurable disease that chokes off breathing, has been the primary or contributing cause of death for more than 76,000 miners since 1968, costing the government $45 billion in benefits to miners and their families.
More than 40 percent of longtime miners in some regions got the disease before Congress approved rules in 1969 limiting underground miners' exposure to breathable dust kicked up during mining.
The prevalence of black lung dropped sharply afterward, dipping to 2 percent in screenings conducted from 1995 to 1999, according to the National Institute for Occupational Safety and Health, or NIOSH.
However, it started going back up after that, reaching 3.3 percent among surveyed miners in 2005 and 2006, NIOSH has said.
The level was worse in Eastern Kentucky, where 9 percent of the miners screened in one NIOSH program from 2005 through 2009 had the disease.
The agency also began seeing miners with advanced cases of the disease at younger ages, and documented a 40-year high of the most lethal form of black lung, NIOSH researchers have said.
MSHA put new rules in place beginning Aug. 1 aimed at eliminating the disease.
The agency lowered the level of coal and rock dust to which miners legally may be exposed, required personal dust monitors for miners to provide real-time information on exposure, and made several changes in how companies must monitor dust levels in mines.
For instance, the old rules allowed companies to take samples when there was less production going on, meaning less dust would be generated. The new rule requires dust samples be taken when production is at least 80 percent of capacity.
Coal companies and industry groups have sued, arguing that MSHA overstepped its authority in adopting the new rules, failed to properly analyze their feasibility, relied on flawed data, and required use of an inferior sampling method, among other things.
The industry argued that most companies comply with health and safety rules. The spike in black lung has been in Central Appalachia, including Eastern Kentucky, and MSHA should have tried increased enforcement there instead of putting new limits on all operators, the industry has argued.
However, NIOSH had called for a lower respirable-dust limit for years, and MSHA projected that the industry's cost to meet the standards would be less than the benefits from a reduction in black-lung cases.
Researchers have identified a number of possible factors in the increase in black lung, including longer working shifts for underground miners; increased mining of thinner coal seams in Central Appalachia, which requires cutting through more rock; inadequate dust-control rules; and the failure by companies to comply with the rules.
Safety advocates and retired miners also have alleged cheating by companies on dust sampling.