While many workers have to take steps to avoid frostbite and hypothermia during the winter, miners face an even greater danger: explosions. Statistics show that coal-mine explosions occur most often during the colder months, October through March.

The U.S. Department of Labor's Mine Safety and Health Administration (MSHA) has placed Dennis Creg Yonts' Mine No. 2 in Letcher County, Ky., operated by Vision Coal, on potential pattern of violations status based on data gathered during agency audits.

Twenty-two of the coal miners trapped in a flooded mine in northeast China since August 19 have been rescued, according to a statement released by the vice governor of the province where the illegal mine is located.