Typically, when people think of a coal mine, they think of people with lights on their hard-hats, working underground in very dusty, dark, hot, humid and dangerous conditions. However a surface coal mine, like Wyodak, has workers in the sunlight and working in equipment that is air-conditioned and heated. An ailment associated with coal mining is pneumoconiosis , or Black Lung. That ailment, to date, has not been associated with surface coal mining. Surface miners aren't exposed to the same levels of dust as those found in underground coal mines.
Underground mining is a much more hazardous situation.
MSHA, the Mine Safety Health Administration , a division of the Department of Labor, has total jurisdiction over all permitted mine sites in the United States. They perform inspections, impose fines, write citations and can even close a mine if they feel conditions present immediate danger.