In 1907, 3,242 miners died on the job in the United States [source: MSHA]. Fortunately, that number has decreased significantly as the decades have passed. But in 2010, the number of deaths increased for the first time in years -- 71, compared to 2009's 34 [source: MSHA]. An explosion at West Virginia's Upper Big Branch Mine in April 2010 killed 29 people, the worst mining disaster since a 1970 explosion in Kentucky resulted in the deaths of 38 people [source: Urbina].
Most injuries and fatalities occur at coal mines. The most common cause of death in these accidents? Ignition or explosion. Powered haulage and roof falls also claim lives [source: MSHA].
Perhaps most infamous is black lung, the common name for pneumoconiosis, which is caused by breathing in coal dust. The dust inflames your air sacs and causes scarring and lung damage. Its symptoms are a cough that doesn't quit and shortness of breath -- and lungs that have quite literally turned black as coal.