CHARLESTON, W.Va. -- Citing a "grave danger" to the nation's coal miners, the Obama administration said Tuesday that mine operators must take additional steps to control the buildup of highly explosive coal dust underground.
The U.S. Mine Safety and Health Administration issued an emergency rule that will force operators to apply more crushed stone to the walls, floors and other surfaces in underground coal mines.
Experts from the National Institute for Occupational Safety and Health urged a toughening of federal "rock dusting" standards in reports published in 2006 and 2009. But MSHA officials did not act until another NIOSH report was published this May, a month after 29 miners died in an explosion at Massey Energy's Upper Big Branch Mine in Raleigh County.
"It's something that's long overdue," said Dennis O'Dell, safety and health director for the United Mine Workers union. "We support it, absolutely."
Coal dust is highly explosive, and can turn what might be minor ignitions of methane gas in underground mines into massive blasts that take many more lives. Federal and state investigators and independent experts believe that's exactly what happened on April 5, when a huge explosion ripped through the Upper Big Branch Mine, causing the worst U.S. coal-mining disaster in 40 years.
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.
Under the 1969 federal Coal Mine Health and Safety act, coal companies must apply enough rock dust so that "incombustible content" of mine dust in clean-air intake tunnels makes up at least 65 percent of all dust measured. In "return air" sources, rock dusting must be adequate to make the incombustible content 80 percent of all dust measured.
But that 41-year-old law is based on coal-dust surveys of U.S. mines conducted in the 1920s. More recent NIOSH studies, conducted after a series of disasters in 2006, found that more modern and highly mechanized mining practices produce significantly finer coal dust that requires more rock dust to control.