When Pennsylvania ordered coal mines closed because of the coronavirus, then reversed course and declared them to be “essential,” West Virginia Gov. Jim Justice, who made a fortune in coal, was quick to mock his neighbors.

“Coal is so essential it is unbelievable,” said Justice, a Republican. “We have to have good electricity flowing into our homes.”

The mine workers union agrees with him. So does President Trump, who has spent the past three years talking up the coal business.

But in the face of the pandemic, is coal mining actually so essential?

Because of the nature of the work — a lot of crowding, coughing and spitting — and the significant incidence of lung damage from years of exposure to coal dust, silica and diesel exhaust, coal miners may be especially vulnerable to the coronavirus, medical researchers say. And coal provides less than a quarter of America’s electricity, at a moment when demand for power is falling and there are already large stockpiles of coal nationwide because of the warm winter, as well as a glut of cheap natural gas.

In fact, last week, as oil prices collapsed and gas continued its downward slide, coal for the first time became the most expensive fossil fuel. There are about 51,000 miners employed in surface and underground mining in the United States, according to the U.S. Department Bureau of Labor Statistics.

On the economics alone, said Jeremy Richardson, a senior energy analyst with the Union of Concerned Scientists, “for a lot of plants, it would just make sense to shut down for now.” The rest of the grid has plenty of capacity, he said.

But there’s more than economics at stake. Though black lung disease sharply fell among miners from the 1970s to the 1990s, it has been on the rise since then. A Centers for Disease Control and Prevention study found that more than 10 percent of the longest-tenured miners are still working even as they have the disease, and it afflicts a smaller portion of younger miners, as well.

“Adding an infection to a coexisting lung disease can make things worse,” said Anna Allen, a doctor who studies black lung disease at West Virginia University. “It’s not unusual for us to find coal miners who have early-stage disease, feel fine, think they’re okay.” But, she said, they’ve already lost a portion of their reserve lung capacity.

The complications from the coronavirus occur when the virus settles in the lungs and results in pneumonia.

With black lung disease and silicosis, said Robert Cohen, a doctor who is the principal investigator at the Black Lung Clinic Program at the University of Illinois at Chicago, “you damage the lung’s ability to heal itself and to resist further damage.”

Miners can be stubborn, though.

“A lot of things can get you in the mines,” said William J. McCool, who lives outside Whitesburg, Ky., and spent 40 years as a miner. Water, rocks, air, equipment — any of those can go wrong, he said. McCool retired eight years ago with a bad case of black lung, but if he were still working today, he’d probably go on down.

“It was exciting. Every day was different. You were with your buddies all the time. I never had no trouble,” he said. A disease might catch you, he said, but it’s sad, too, “when a whole mountain falls on you — nothing but rock.”

The United Mine Workers of America, the once-powerful union, argues that the work is essential and the mines should stay open. But a spokesman, Phil Smith, cautions that the riskiest aspect of the job is in the locker rooms and “mantrips,” or mine cars, that carry the workers to the face, or the surface where mining work is advancing. In these places, more than at the work site, conditions are most crowded and the chances of infection the greatest.

“After they change into their work clothes they hang around for a while waiting for their shift to start,” he said. “It can be a couple of hundred people.”

Unionized mining companies are providing materials to wipe down surfaces, he said. “Beyond that, it’s pretty hard to maintain the level of social distancing you might want.”

Cohen agrees. On the elevators that take miners up and down in some shafts, he said, “they pack them in like a subway in Japan.”

But the coal face isn’t such a safe place, either, he said, even though miners are more spread out there. “You’re coughing, you’re spitting, you’re wiping your nose.” There’s no hand sanitizer along a seam of coal, nor a nearby washroom. Miners typically don’t wear respirator masks because they make it too difficult to do heavy labor.

If mining is essential, Cohen said, then it’s appropriate to ask miners to make the sacrifice, and take the risk.

One coal company in Kentucky, Blackhawk Mining, voluntarily announced a shutdown of operations last week because of the pandemic. Its workers won’t be paid but will keep their benefits while on furlough.

“We have been following the CDC’s recommended guidelines for minimizing workplace impacts and have been actively encouraging sick employees to stay home,” the company’s president, Jesse Parrish, said in a statement.

“Despite our best efforts, and considering the growing rate of infection, our company feels compelled to take additional measures. We regret the impact of these actions and realize that this may cause certain hardships on our employees and stakeholders.”

Last week, Pennsylvania Gov. Tom Wolf, a Democrat, included mining on a list of “nonessential” industries that should close because of the coronavirus. But a day later, the state moved it to the “essential” column.

Dominique Lockett, a spokeswoman for the state’s Department of Community and Economic Development, said the change was made after state officials consulted a list of “critical infrastructure” categories identified in an advisory issued by the U.S. Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency.

Most of the coal mined in the United States is used by power plants. A little less than 3 percent is needed for the production of steel.

Justice is reported to be the wealthiest person in West Virginia, with a billion-dollar-plus fortune based on his holdings in Bluestone Industries and Bluestone Coal. An NPR story in 2016 found Justice’s companies had failed to pay millions of dollars in mine-safety penalties.

Elected as a Democrat, Justice switched parties in 2017 and embraced Trump over the president’s enthusiasm for coal. West Virginia is the second-largest producer of coal, after Wyoming.

Last week he closed the Greenbrier resort, which he also owns, because of the pandemic, but said he had no intention of sending coal miners home on furlough.

“Absolutely they’re essential in my book,” he said, “in every way, shape, form and fashion.”

The National Mining Association also argues that mines should remain open.

“Coal continues to provide a quarter of the nation’s electricity generation,” it said in a post Monday. “And in many states, coal is far-and-away the leading fuel for electricity generation.”

The National Mining Association has been seeking since last week a $220 million rollback of taxes it pays to support 25,700 disabled miners and their dependents, as well as cuts in mandated cleanup costs.

“It’s just horrible they would do that now,” Richardson said. “It really speaks to the need for investing in rural health care.”

Those retired miners with black lung disease are of course also at increased risk of serious complications from the coronavirus. If normal breathing is like blowing up a balloon, said Allen, of West Virginia University, breathing with black lung is like trying to inflate a bicycle tire. The scarring in the lungs gives them less capacity to handle a case of pneumonia.

“There’s a lot of concern,” said Rebecca Shelton, of the Appalachian Citizens’ Law Center, in Whitesburg, Ky., which advocates on behalf of black lung sufferers. “Our main focus right now is how we can get the best information out there — what they can look out for, and how they can protect themselves.”