A new coal mining rule goes into effect tomorrow that regulators hope will help prevent explosions like the one at the Upper Big Branch Mine last year. The federal Mine Safety and Health Administration will require coal mine dust to be at least 80 percent rock dust, which is non-combustible. The other 20 percent can be coal dust, which can cause explosions.Dennis O’Dell is the Administrator of Occupational Health and Safety for the United Mine Workers of America.“We can always make improvements but this is definitely a vast improvement considering that the rock dust standard hasn’t been changed since the 1920s,” he said. “So, I would say that this is something that, once applied, will help.”O’Dell says that most mines already make sure more than 80 percent of their dust is rock dust.“A lot of mines go above and beyond. This was just more or less to bring some of those outlaw bandits out there up to the same standard that the reputable operators were trying to do to protect the miners. Hopefully this will get us where we need to be.”Mine operators have had to comply with this rule since September, when an Emergency Temporary Standard went into place, but this final rule makes the change permanent.