The rules were developed as a result of a federal review of accident investigation reports of mine explosions in intake air courses that involved coal dust.

MSHA also utilized the findings in the National Institute for Occupational Safety and Health report Recommendations for a New Rock Dusting Standard to Prevent Coal Dust Explosions in Intake Airways.

An emergency temporary standard was issued last September and the final rule maintains those same requirements.

Mine operators are now required to maintain the percentage of incombustible content of combined coal dust, rock dust and other dust at 80% in all accessible areas of underground bituminous coal mines, plus an additional 0.4% for each 0.1% of methane where methane is present in any ventilating current.

Like the temporary version, the final rule also increases the total required incombustible content for all areas of a mine outside of return air courses from 65% to 80%.

"This rule is an important next step in the Labor Department's efforts to keep our miners safe," secretary of labor Hilda Solis said.

"Inadequate rock dusting can increase the potential for explosions that destroy mines, lives, families and communities, and we must minimize that potential."

MSHA assistant secretary Joseph Main said the agency responded rapidly to the NIOSH report, which included new scientific evidence calling for an improved rock dusting standard.

"We are committed to enforcing this important standard that ultimately will save lives and we expect mine operators to act quickly to reduce the threat to those mining coal underground," he said.

MSHA has posted the final rule in its entirety on its web site as well as in the Federal Register. A video overview showing the danger of un-neutralized coal dust in mine explosions is available at http://www.msha.gov/streaming/wvx/floatcoal.wvx.

To view a full copy of the NIOSH report, visit http://www.cdc.gov/niosh/mining/pubs/pubreference/outputid2825.htm.