Black lung is the miner's malady -- a deadly disease tied to years of coal dust inhalation.
Though stricter safety standards have led to a decline in black lung deaths since the 1970s, the disease still looms in mining states such as Pennsylvania and West Virginia, according to data from the U.S. Centers for Disease Control and Prevention and the National Institute for Occupational Safety and Health, and is at the center of a new yearlong investigation by ABC News' Chief Investigative Correspondent Brian Ross.
WATCH the full report tonight on ABC News "World News With Diane Sawyer" at 6:30 p.m. EST and "Nightline" at 12:35 a.m. EST.
Black lung earned its name from the appearance of the organ it attacks. Unlike the pink, fleshy lungs of a non-miner, those of a black lung patient are bespeckled with black coal dust.
The dust becomes trapped in the lungs, where it triggers inflammation and then scarring. Over time, symptoms like coughing and shortness of breath can give way to chronic obstructive pulmonary disease, respiratory and heart failure and even death, according to the National Institutes of Health.
INVESTIGATION: For Top-Ranked Hospital, Tough Questions About Black Lung and Money
More than 10,400 Americans died from black lung between 1995 and 2004, according to the latest Work-Related Lung Disease Surveillance Report released in 2007. Pennsylvania and West Virginia were hit hardest, with more than 6,200 deaths between them.
The disease, also known as coal worker's pneumoconiosis, has no specific treatment, according to the NIH. Instead, miners are urged to avoid inhaling coal dust.