The nation's coal mines were in compliance on nearly all dust samples taken this year with new monitors aimed at cutting miners' exposure to particles that can cause deadly black lung disease, federal regulators announced Monday.

The coal industry had challenged the new dust-control rule, arguing among other things that the monitors had a high failure rate.

However,
Joseph A. Main, head of the U.S. Mine Safety and Health Administration, said Monday the sampling results show the monitors and the rule work to protect miners.

The latest phase of tougher dust-control rules in coal mines took effect Feb 1.

It required companies to begin using continuous personal dust monitors on miners in the dustiest jobs and to conduct more sampling.

The monitors give miners and supervisors real-time information about dust levels so they can make adjustments to lower exposure to dust, Main said.

Under the old rules, it could take days or weeks for test results to show the concentration of dust miners had worked in.

MSHA announced Monday that it had analyzed more than 20,000 dust samples collected by the personal monitors in underground coal mines from April 1 to June 30, and about 99 percent complied with exposure limits.

In addition, MSHA said more than 98 percent of the samples would have been in compliance with a new standard set to take effect Aug. 1, when the permissible exposure level of breathable dust for a miner will drop from 2 milligrams per cubic meter of air to 1.5 mg.

The results show the industry can meet the lower limit, Main told the Herald-Leader.

"We know that's an achievable standard," Main said.

MSHA began phasing in new standards in 2014 to try to cut coal miners' exposure to dust churned up during mining.

The dust can cause black lung, an incurable disease that impairs breathing and causes premature death. The disease has been the primary or contributing cause of death of more than 76,000 miners since 1968, according to MSHA.

The prevalence of black lung dropped markedly after Congress approved rules in 1969 to limit miners' exposure to dust, but began increasing in the late 1990s.

Eastern Kentucky has been a hot spot for the resurgence. In one round of screening from 2005 through 2009, 9 percent of Eastern Kentucky miners screened had the disease.

Main said one problem is that the old dust-control rules were not adequate.

Miners have also said coal companies sometimes failed to comply with the rules, tampering with samples to make it appear mines were not as dusty as they really were.

In announcing the test results Monday, Main credited the efforts of the coal industry and MSHA to clean up the air in coal mines air and implement the dust rule to protect miners.

Luke Popovich, spokesman for the National Mining Association, also pointed to the industry's continuing effort to lower dust levels.

"We are pleased to see this record of improvement and look forward to working with MSHA to achieve the reductions we all desire," Popovich said.

The coal industry had challenged the dust rule, arguing MSHA failed to show it was technologically and economically feasible and put in flawed sampling requirements, and questioning the reliability of the personal monitors.

Main, however, said the monitors had been proven in independent testing.

A federal appeals court said MSHA had adequate evidence to conclude the monitors will produce accurate results, and turned down the industry challenge.

Popovich said the industry continues to have questions about the technology and expects more to arise, given that the monitors have only been in use five months.

However, the industry did not appeal the court ruling.

Bill Estep: 606-678-4655, @billestep1

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