Federal officials are warning about the dangers of inhaling chemicals at oil wells following the deaths of nine workers over the last five years.
All of the deaths involved workers at crude production tanks. Colorado and North Dakota each had three deaths and Texas, Oklahoma and Montana each had one death.
The Denver Post reports that most were originally considered to be due to natural causes or heart failure. But the men were later found to have all inhaled toxic amounts of hydrocarbon chemicals after either taking measurements of oil or other byproducts in the tank or takings samples of oil for testing.
The industry says the sudden rise in deaths could be linked to the number of inexperienced workers brought in to work during the energy boom.