Thousands of veterans fear "burn pits" exposed them to lethal disease

Over 1.5 million American troops were deployed to Iraq and Afghanistan between 2001 and 2011. Many returned with visible scars of war – but for some, their injury is hidden. At some of the military bases throughout those regions, waste materials were disposed of in so-called "burn pits." Breathing fumes from the burn pit fires appears to have damaged the health of countless veterans.

Air Force veteran Dan Jentik struggles with what most don't even think about: taking a breath. Jentik is part of a lung study at the National Jewish hospital in Denver. But he's also part of a much larger group: he was one of thousands of men and women who served in Iraq and Afghanistan who may be sick or dying because they inhaled smoke from massive burn pits next to their bases.

Jentik said the pits smelled acrid, like "when you burn plastic." He said, "you just constantly saw the smoke or you smelled it, pretty much everyday, all day."