WASHINGTON (AP) — The Obama administration said Wednesday it is cutting the amount of coal dust allowed in coal mines in an effort to help reduce black lung disease. Perez was one of several top government officials to announce the long-awaited final rule Wednesday at an event in Morgantown, W.Va. Black lung is an irreversible and potentially deadly disease caused by exposure to coal dust, where the dust particles accumulate in the lungs. The rule by the Labor Department's Mine Safety and Health Administration lowers the overall dust standard from 2.0 to 1.5 milligrams per cubic meter of air.