UPDATED 18:49 PM EST, January 17, 2013
The changes were first proposed less than a year after the Upper Big Branch mine exploded in April 2010, killing 29 men. It was the worst U.S. coal mine disaster in four decades, and Labor Secretary Hilda Solis said her agency has since undertaken "a serious and comprehensive evaluation of mine safety practices."
The Mine Safety and Health Administration said the new rules could help prevent a disaster like Upper Big Branch.
