CHARLESTON, W.Va. -- Federal and state standards for controlling coal dust in underground mines date back nearly a century, and are not adequate to prevent explosions in modern, highly-mechanized operations, according to government research that regulators have never acted upon.
Researchers at the National Institute for Occupational Safety and Health published reports in 2006 and 2009 urging regulatory agencies to re-examine the standards, but no such action has been taken.
Joe Main, assistant labor secretary for the U.S. Mine Safety and Health Administration, said the NIOSH recommendations would get a closer look in the wake of last week's deadly explosion at Massey Energy's Upper Big Branch Mine in Raleigh County.
"I think you can pretty well expect that to be on the table," Main said in an interview Tuesday afternoon.
Gov. Joe Manchin said Tuesday he is considering emergency action to tighten West Virginia's dust standard until he can call the Legislature into special session to pass a new law.
"I'm going to do everything I can in this state," Manchin said. "I can't wait until the feds start moving."
Coal dust is highly explosive, as is methane gas, which is naturally liberated by geologic formations underground.
If methane builds to explosive levels and is ignited, coal dust can be tossed into the air and explode -- making underground blasts 10 times more powerful. When methane ignites in the presence of excessive dust, an explosion that might have caused minor damage or injured miners can easily shoot through mine tunnels, killing dozens of workers.
Investigators digging into the cause of last week's explosion that killed 29 workers at Massey Energy's Upper Big Branch Mine in Raleigh County are focusing on their belief that coal-dust accumulations made the disaster far worse. The operation has been repeatedly cited not just for ventilation problems, but also for unsafe levels of coal dust.
Mine safety experts have known for decades how to prevent coal dust explosions: Apply large amounts of "rock dust," usually powdered limestone, to wall and floor surfaces underground. Even if there is an explosion, the rock dust mixes with coal dust and helps prevent it from fueling a larger blast, experts say.
Under current federal regulations and West Virginia rules, coal companies must apply enough rock dust so that the "incombustible content" of mine dust in clean-air intake tunnels makes up at least 65 percent of all dust measured. In "return air" courses, rock dusting must be adequate to make the incombustible content 85 percent of all dust measured.
But those rules are based on dust surveys of U.S. mines conducted in the 1920s.
Four years ago, after a series of deadly mine disasters in West Virginia and Kentucky, NIOSH conducted the first comprehensive survey of coal dust in more than 80 years. The agency examined coal-dust particle size, which is important because smaller and finer dust particles require more rock-dusting to prevent explosions.
Michael J. Sapko and other NIOSH researchers examined coal-dust samples from 50 mines across the country.
"Underground coal mining technology has become highly mechanized, and this has resulted in increased coal production rates," Sapko wrote in an August 2006 paper. "Coal mining has become highly mechanized and this has resulted in increased coal production rates.