Denver Brock and his son Aundra used to spend early mornings hunting rabbits in the wooded highlands of Harlan County, Kentucky. But they don’t get out there much these days. They both get too breathless.

Instead, they tend a large garden alongside Denver Brock’s home. Even that can prove difficult, requiring them to work slowly and take frequent breaks.

“You get so dizzy,” Denver Brock said, “you can’t hardly stand up.”

The Brocks both have coal workers’ pneumoconiosis, a debilitating disease characterized by masses and scarred tissue in the chest, and better known by its colloquial name: black lung.

Denver Brock, 73, wasn’t all that surprised when he was diagnosed in his mid-60s. In coal mining communities, black lung has long been considered an “old man’s disease,” one to be almost expected after enough years underground.

But his son was diagnosed much younger, at 41. Like his father, he has progressive massive fibrosis, the most severe form of the disease. And today, at 48, he’s even sicker.

When Aundra Brock followed his father into mining, he thought he was entering a safer industry. By the 1990s, safety standards and miner protections had nearly consigned the disease to history.

But now, black lung is back.

Modern miners are contracting it at younger ages and at rates not seen since the 1970s. For 20th- century miners, it could take decades to develop severe black lung. For men of Aundra Brock’s generation, just a few years can be enough. Nationwide, 1 in 10 working miners is now estimated to have black lung. In the heart of the central Appalachian coalfields, it’s 1 in 5. Often, their disease is more severe, the progression faster.

Experts say it should be possible to reverse the trend.

“The entire thing about this whole disease is it’s 100% preventable,” said Dr. Robert Cohen, a pulmonologist at the University of Illinois Chicago. “It’s not an act of God or an act of nature. It’s not something out of our control. In a wealthy country with a wealthy economy, we should be able to do better.”

From an industry perspective, miner health and safety “is always an area that can be improved,” said Ashley Burke, a spokesperson for the National Mining Association, which represents more than 250 companies. Burke said the association has supported mandatory screenings, research into technologies that could protect miners and an expedited government approval process for new equipment.

But as President Donald Trump aims to revitalize the mining industry, doctors and researchers like Cohen also worry that federal government cuts are hampering efforts to find a solution.

When Dr. Brandon Crum, 50, opened his radiology clinic in Coal Run Village, Kentucky, in 2013, he didn’t expect to encounter many grave cases of black lung.

Rates had fallen in the years after Congress passed the Coal Mine Health and Safety Act of 1969, which put limitations on acceptable levels of dust and established a federal program for black lung benefits. During the 1990s, the government documented only a few dozen cases, a low number even when accounting for the steep decline in mining jobs. Progressive massive fibrosis was nearly eradicated.

Crum, a Kentucky native, was well aware of the trends. But quickly, he began seeing a shocking amount of progressive massive fibrosis: 60 cases over about 18 months. And the patients were often younger. One was just 44.

Progressive massive fibrosis occurs when dust settles in the lungs, and over time the resulting inflammation turns to hardened tissue. Medication can sometimes slow the disease’s progression, but there is no cure. Hearts fail. People can struggle to breathe as their chests fill with fluid.

In 2016, Crum attended a black lung conference in West Virginia in hopes of speaking to Scott Laney, an epidemiologist at the National Institute for Occupational Safety and Health and the chief scientist of the institute’s health surveillance program for coal workers. Crum explained what he was seeing.

Laney was skeptical, but agreed to travel to the clinic in Coal Run. There, Laney viewed one X-ray after another of the worst black lung he had ever seen.

“I was sick to my stomach,” he said. “I could not believe my eyes.”

Around the same time, Cohen noticed something was amiss too.

When Cohen and his colleagues analyzed the lung tissue of 13 miners from West Virginia, Kentucky and Pennsylvania, they were alarmed to find that only one had classic coal-based black lung. The others all had silicosis.

Silicosis is caused by inhaling a mineral called crystalline silica that is typically found in sand, stone and concrete. It is a building block of the Appalachians. But in the air, it is dangerous, able to create much worse scarring in the lungs than coal dust alone. Breathing the coal and silica dust together can create a kind of hybrid disease that quickly leads to progressive massive fibrosis.

In 1974, the occupational health institute tried to limit miners’ exposure to silica by recommending mine operators ensure that their workers weren’t breathing more than 50 micrograms of silica per cubic meter of air. Regulators set the exposure limit twice as high.

Back when Denver Brock’s career began in 1969, it was typical to be working along an underground wall of coal. Today, many of those large coal deposits have been mined out of central Appalachia. The coal that remains is encased in thick layers of quartz and sandstone. When miners drill, cut and blast it apart, that rock turns to crystalline silica dust.

On April 1, more than 800 people at the National Institute for Occupational Safety and Health, including Laney, received notices that their jobs had been eliminated as part of broader federal cuts. After a federal judge issued an injunction, Laney and others in the coal workers’ health surveillance program got their jobs back. But many other government scientists focused on solving the black lung problem did not.

The cuts have had a ripple effect.

For more than a decade, an agency within the Department of Labor, the Mine Safety and Health Administration, had been using the occupational health institute’s data, as well as the research of Cohen and others, to develop a case for lowering the silica exposure threshold.

Last year, the agency finally issued a new standard, reducing the limit to the 50 micrograms that was recommended decades ago. It was set to go into effect this April.

But in the wake of “unforeseen NIOSH restructuring,” the agency announced it would pause implementation of the rule. The announcement came less than a week before enforcement was set to begin, and on the same day Trump signed executive orders aimed at bolstering what he called the “beautiful clean coal industry.”