Maintenance of Incombustible Content of Rock Dust in Underground Coal Mines

This final rule replaces the Mine Safety and Health Administration's Emergency Temporary Standard (ETS) pursuant to section 101(b) of the Federal Mine Safety and Health Act of 1977. The final rule adopts the requirements contained in the ETS. Under the final rule, mine operators must maintain the incombustible content of combined coal dust, rock dust, and other dust to at least 80 percent in underground areas of bituminous coal mines. The final rule further requires that the incombustible content of such combined dust be increased 0.4 percent for each 0.1 percent of methane present. Accumulations of coal dust can ignite, resulting in an explosion, or after an explosion, they can intensify flame propagation, increasing the severity of explosions. The final rule, like the ETS, reduces both the potential for a coal mine explosion and the severity of explosions should they occur.