He's one of a handful of miners on an April afternoon to move through the RV parked at the fire department in Wharton. Inside, a team of NIOSH workers shepherds them from station to station: medical history, questionnaire, breathing test, chest X-ray. Foster hopes the tests will provide evidence he can use to submit a claim for benefits. Other miners are still working and want to make sure their lungs are clear.

It is from this rolling medical unit, in part, that NIOSH has documented the return of black lung. For decades, miners have been entitled to free X-rays every five years, and this has helped track the drop in the disease's prevalence. After the data started showing a reversal, NIOSH sent its RV out to gather more data in 2005.

What these researchers found, combined with data from routine medical monitoring, was worrisome: From the 1970s through the 1990s, the proportion of miners with signs of black lung among those who submitted X-rays dropped from 6.5 percent to 2.1 percent. During the most recent decade, it jumped to 3.2 percent.

In a triangle of Appalachia - southern West Virginia, eastern Kentucky and western Virginia - the numbers were even higher. The NIOSH unit found a disease prevalence of 9 percent in Kentucky from 2005 to 2009, for example.

Prevalence of the most severe form of black lung has tripled between the 1980s and the 2000s and has almost reached the levels of the 1970s.

A wake-up call for some came after the Upper Big Branch explosion in southern West Virginia in April 2010, which killed 29 miners. Of the 24 who had enough lung tissue for an autopsy, 17 had signs of black lung. Some had as few as 10 years of experience in mines; they ranged in age from 25 to 61.

Black lung leaves miners' lungs scarred, shriveled and black. They struggle to do routine tasks and are eventually forced to choose between eating and breathing.

"No human being should have to go through the misery that dying of [black lung] entails," said Dr. Edward Petsonk, who treats patients with black lung and works with NIOSH. "It is like a screw being slowly tightened across your throat. It is really almost a diabolical torture."

Underpinnings of an epidemic

There are theories about why the disease has returned, but no definitive answers. One likely explanation: Miners are breathing a more potent mix of dust. Coal seams are surrounded by rock, much of which contains the mineral silica. When ground up, silica is more toxic to the lungs than coal dust and can cause faster-progressing disease.

With larger coal seams becoming mined out, companies are turning to thinner seams surrounded by more rock. At the same time, because of the price of coal and advances in mining equipment, it now makes more sense economically for companies to cut through large amounts of rock to get at the coal.

NIOSH research suggests this may be having an effect. A particular marker on an X-ray is often indicative of silica-related disease. Comparing miners' X-rays taken from 2000 to 2008 with those taken from 1980-1999, researchers found that the proportion bearing these markers had nearly quadrupled and, in central Appalachia, had increased almost eight times over.

Rules are supposed to limit the amount of silica in the air in mines, but a Center for Public Integrity analysis of MSHA's dust sampling database, obtained under the Freedom of Information Act, shows that the agency has long failed to control silica dust. In each of the past 25 years, the analysis found, the average valid silica sample has been above the allowed level.

Another possible explanation for black lung's resurgence:  The number of hours worked by miners has steadily increased over the past three decades, MSHA data show. Longer hours mean more exposure to dust and less recovery time.

At the same time, production has increased, thanks in part to powerful new equipment. A longwall shearer, for example, can carve out huge swaths of coal in little time.

Mark McCowan ran one of these behemoths for the final years of his career. "By the time I was 40 years old, I had mined more coal than most miners mine in a lifetime," he recalled, sitting in his living room in Pounding Mill, Va.

McCowan was diagnosed with black lung at age 40. His disease has progressed to the most severe form; now 47, he finds it harder and harder to breathe. He pointed to a photo of a beaming, blond-haired 2-year-old on his wall - his grandson, Haiden. McCowan sees him two or three times a week and plays with him for as long as his lungs can take. "My biggest fear," he said, "is I won't live long enough for him to remember me."

***

Our stories about black lung were jointly reported by the Center for Public Integrity and NPR News as part of "Hard Labor," an occasional series on health, safety and economic threats to U.S. workers. Additional reporting was provided by Charleston Gazette staff writer Ken Ward Jr.

Read more in Monday's Gazette and on the CPI website, http://www.iwatchnews.org/.

Graphic:Black lung by the numbers
Read more:Dust reforms stalled by years of inaction
Miners say UBB mine cheated on dust sampling

PRESTONSBURG, Ky. -- Ray Marcum bears the marks of a bygone era of coal mining. At 83, his voice is raspy, his eastern Kentucky accent thick and his forearms leathery. A black pouch of Stoker's 24C chewing tobacco pokes out of the back pocket of his jeans. "I started chewing in the mines to keep the coal dust out of my mouth," he says.

Plenty of that dust still found its way to his lungs. For the past 30 years, he's gotten a monthly check to compensate him for the disease that steals his breath -- the old bane of miners known as black lung.

In mid-century, when Marcum worked, dust filled the mines, largely uncontrolled. Almost half of miners who worked at least 25 years contracted the disease. Amid strikes throughout the West Virginia coalfields, Congress made a promise in 1969: Mining companies would have to keep dust levels down, and black lung would be virtually eradicated.

Marcum doesn't have to look far to see that hasn't happened. There's his middle son, Donald, who, at 51, has had eight pieces of his lungs removed. He sometimes has trouble making it through a prayer when he's filling in as a preacher at Solid Rock Baptist Church.

There's James, the youngest.  At 50, his breathing is becoming more labored, and his doctor has already discussed hooking him up to an oxygen tank part-time.

Both began working in the late 1970s - years after dust rules took effect - and both began displaying symptoms in their 30s. Donald now has the most severe, fastest-progressing form of the disease, known as complicated coal workers' pneumoconiosis.  James and the oldest Marcum son, Thomas, 59, have a simpler form, but James has reached the worst stage and is deteriorating.

Men with lungs like the Marcums' aren't supposed to exist. "In 1969, I publicly proclaimed that the disease would go away before we learned more about it," said Dr. Donald Rasmussen, a pioneer in recognizing and diagnosing black lung who is still practicing, at 84, in Beckley, W.Va. "I was dead wrong."

Throughout the coalfields of Appalachia, in small community clinics and in government labs, it has become clear: Black lung is back.

The disease's resurgence represents a failure to deliver on a 40-year-old pledge to miners in which few are blameless, an investigation by the Center for Public Integrity and NPR has found. The system for monitoring dust levels is tailor-made for cheating, and mining companies haven't been shy about doing so. Meanwhile, regulators have sometimes neglected to enforce even these porous rules.

A Center analysis of databases maintained by the federal Mine Safety and Health Administration found that miners have been breathing too much dust for years, but MSHA has issued relatively few violations and routinely allowed companies extra time to fix problems.

MSHA chief Joe Main issued a statement in response to the findings: "The current rules have been in effect for decades, do not adequately protect miners from disease and are in need of reform. That is why MSHA has proposed several changes to overhaul the current standards and reduce miners' exposure to unhealthy dust." Similar attempts at reform have died twice before.

From 1968 through 2007, black lung caused or contributed to roughly 75,000 deaths nationwide, according to government data.  In the decades following passage of the 1969 law, rates of the disease dropped significantly. Then, around the late 1990s, this trend reversed.

Many of the newer cases have taken a particularly ugly form. While rates of black lung overall have increased, incidence of the most severe, fast-progressing type has jumped significantly. These cases, moreover, are occurring in younger and younger miners. Of particular concern are "hot spots" identified in central Appalachia by the National Institute for Occupational Safety and Health, NIOSH, a government research agency.

"I think any reasonable epidemiologist would have to consider this an epidemic," said NIOSH's Scott Laney.

The National Mining Association, a trade group representing mining companies, agrees that black lung's comeback is a problem in need of attention. To the association, however, it is primarily a regional phenomenon - one that doesn't justify new national rules. What's needed, it says, is more research and better enforcement of current standards.

'A diabolical torture'

"They call me Lucky," retired miner James Foster says as he takes off his shirt and presses his chest against an X-ray machine in the back of an RV in Wharton, W.Va. "Worked 37 years in all kinds of mines. Been covered up twice. Been electrocuted."

His brushes with death aside, he's here because he fears there may be one hazard he can't dodge. "I come in here to file for my black lung," he says. During a recent heart surgery, he says, doctors said they saw what appeared to be signs of the disease.

He's one of a handful of miners on an April afternoon to move through the RV parked at the fire department in Wharton. Inside, a team of NIOSH workers shepherds them from station to station: medical history, questionnaire, breathing test, chest X-ray. Foster hopes the tests will provide evidence he can use to submit a claim for benefits. Other miners are still working and want to make sure their lungs are clear.

It is from this rolling medical unit, in part, that NIOSH has documented the return of black lung. For decades, miners have been entitled to free X-rays every five years, and this has helped track the drop in the disease's prevalence. After the data started showing a reversal, NIOSH sent its RV out to gather more data in 2005.

What these researchers found, combined with data from routine medical monitoring, was worrisome: From the 1970s through the 1990s, the proportion of miners with signs of black lung among those who submitted X-rays dropped from 6.5 percent to 2.1 percent. During the most recent decade, it jumped to 3.2 percent.

In a triangle of Appalachia - southern West Virginia, eastern Kentucky and western Virginia - the numbers were even higher. The NIOSH unit found a disease prevalence of 9 percent in Kentucky from 2005 to 2009, for example.

Prevalence of the most severe form of black lung has tripled between the 1980s and the 2000s and has almost reached the levels of the 1970s.

A wake-up call for some came after the Upper Big Branch explosion in southern West Virginia in April 2010, which killed 29 miners. Of the 24 who had enough lung tissue for an autopsy, 17 had signs of black lung. Some had as few as 10 years of experience in mines; they ranged in age from 25 to 61.

Black lung leaves miners' lungs scarred, shriveled and black. They struggle to do routine tasks and are eventually forced to choose between eating and breathing.

"No human being should have to go through the misery that dying of [black lung] entails," said Dr. Edward Petsonk, who treats patients with black lung and works with NIOSH. "It is like a screw being slowly tightened across your throat. It is really almost a diabolical torture."

Underpinnings of an epidemic

There are theories about why the disease has returned, but no definitive answers. One likely explanation: Miners are breathing a more potent mix of dust. Coal seams are surrounded by rock, much of which contains the mineral silica. When ground up, silica is more toxic to the lungs than coal dust and can cause faster-progressing disease.

With larger coal seams becoming mined out, companies are turning to thinner seams surrounded by more rock. At the same time, because of the price of coal and advances in mining equipment, it now makes more sense economically for companies to cut through large amounts of rock to get at the coal.

NIOSH research suggests this may be having an effect. A particular marker on an X-ray is often indicative of silica-related disease. Comparing miners' X-rays taken from 2000 to 2008 with those taken from 1980-1999, researchers found that the proportion bearing these markers had nearly quadrupled and, in central Appalachia, had increased almost eight times over.

Rules are supposed to limit the amount of silica in the air in mines, but a Center for Public Integrity analysis of MSHA's dust sampling database, obtained under the Freedom of Information Act, shows that the agency has long failed to control silica dust. In each of the past 25 years, the analysis found, the average valid silica sample has been above the allowed level.

Another possible explanation for black lung's resurgence:  The number of hours worked by miners has steadily increased over the past three decades, MSHA data show. Longer hours mean more exposure to dust and less recovery time.

At the same time, production has increased, thanks in part to powerful new equipment. A longwall shearer, for example, can carve out huge swaths of coal in little time.

Mark McCowan ran one of these behemoths for the final years of his career. "By the time I was 40 years old, I had mined more coal than most miners mine in a lifetime," he recalled, sitting in his living room in Pounding Mill, Va.

McCowan was diagnosed with black lung at age 40. His disease has progressed to the most severe form; now 47, he finds it harder and harder to breathe. He pointed to a photo of a beaming, blond-haired 2-year-old on his wall - his grandson, Haiden. McCowan sees him two or three times a week and plays with him for as long as his lungs can take. "My biggest fear," he said, "is I won't live long enough for him to remember me."

***

Our stories about black lung were jointly reported by the Center for Public Integrity and NPR News as part of "Hard Labor," an occasional series on health, safety and economic threats to U.S. workers. Additional reporting was provided by Charleston Gazette staff writer Ken Ward Jr.

Read more in Monday's Gazette and on the CPI website, http://www.iwatchnews.org/.