CHARLESTON, W.Va. -- West Virginia officials have withdrawn two rules addressing what mine operators must do to tamp down explosive coal dust.Monday's decision follows a letter from a Coal Mine Health and Safety board member raising concerns about their provisions.The rules focus on diluting coal dust with inert crushed rock. Coal dust played a role in the worst U.S. coal mining disaster in four decades. Twenty-nine men died in the 2010 explosion at West Virginia's Upper Big Branch mine.Board health and safety administrator Joel Watts urged the rules' disapproval in his Aug. 30 letter. That stance prompted questions from other board members. But not enough of them appeared Monday to conduct an emergency meeting on the subject.Mine officials argue that safety enforcement won't suffer while they revisit the proposed standards.