They were supposed to safeguard miners. They’re charged with cheating on safety tests.

Supervisors who were supposed to help safeguard the health of miners at two Kentucky coal mines conspired to cheat on tests for dust that can cause debilitating black-lung disease, a federal grand jury has charged.

The grand jury indicted eight people who worked at two Armstrong Coal Company underground mines in Muhlenberg and Ohio counties in Western Kentucky.

The company was listed as an unindicted co-conspirator in the alleged crime.

The company endangered miners’ health to save money, the indictment charged.

“By circumventing the dust-sampling procedures, Armstrong Coal and its co-conspirators, avoided implementing ventilation and production controls that might cost money or lower production, and thus were able to save money at the expense of exposing the miners employed at the Parkway and Kronos mines to the risks of breathing air with elevated levels of respirable coal dust, increasing their risks of contracting black lung,” the indictment said.

The indictment is one of the largest mine-safety cases in Kentucky in years, and points up a problem that miners and safety advocates say has not been limited only to the mines named in the indictment.

U.S. Attorney Russell M. Coleman, the federal prosecutor for Western Kentucky, said the investigation that resulted in Wednesday’s indictment continues.

That raises the potential for more people to be charged.

Black lung is an incurable disease caused by breathing dust churned up during coal mining. It impairs breathing and leads to premature death.

“Black lung is a horrible disease. It basically chokes miners to death,” said Tony Oppegard, a Lexington attorney who represented three miners in claims against Armstrong, including the one who initially reported the alleged cheating.

The disease has been the primary or contributing cause of death of more than 75,000 miners since the late 1960s.

Mining companies are supposed to take actions to limit miners’ exposure to breathable dust, such as using ventilation and water sprays to hold down concentrations of dust.

They also are required to monitor dust levels.

The grand jury charged that supervisors at the Parkway mine in Muhlenberg County and the Kronos mine, in Ohio County, schemed to defeat dust-monitoring requirements and cover “pervasive” violations.

The indictment said that the measures supervisors and foremen took included ordering miners to leave dust monitors in areas with cleaner air at times; having miners who were supposed to wear monitors work away form the mine face, where there is more dust; and having miners not wear monitors for their entire shifts.

In one case, two Armstrong employees submitted dust data cards from a time when there was no power on in the mine and it was evacuated, the indictment said.

Those actions would have made the air in the mines appear cleaner than it actually was, and masked the miners’ exposure to dust.

Officials at the mines reported inaccurate readings to the U.S. Mine Safety and Health Administration, the indictment charged.

MSHA relies on reports from the mines to assess compliance. The agency can issue fines for violations.

MSHA did a surprise compliance blitz at the Parkway mine in January 2014 after Justin Greenwell, who operated a machine to install bolts and hold up the mine roof, reported alleged cheating to the agency, according to Oppegard and records.

Inspectors found two monitors that miners at the working face were supposed to be wearing hanging at the power center, where there is less dust.

Oppegard said Greenwell later faced retaliation.

In one case, a company supervisor removed pages from a notebook he was using to record safety concerns, and the company ultimately fired him for allegedly sleeping on the job, which he denied.

Oppegard filed a claim for Greenwell that resulted in him being reinstated, but he later left the mine.

Mike “Flip” Wilson, 63, said he worked at both the mines listed in the indictment at various times in his career of more than 44 years, and that cheating on dust monitoring was common.

But Wilson said he saw that throughout his career at various mines. He was quickly shown how to cover the monitor with a rag after he started working underground in 1974, Wilson said.

Wilson said miners go along with the cheating for fear of getting fired if they don’t.

“I’ve seen’m get fired for it,” he said of refusing to go along with unsafe practices.

Wilson said he was no different for years. Ultimately,though, he decided he didn’t want to see any more young miners exposed to health and safety hazards, and was involved in Greenwell calling MSHA.

He’s also facing the fallout from years of breathing coal dust — black lung. He uses an inhaler to help him breathe and gets winded so easily he can’t walk in the yard with his great-grandsons.

“It’s gonna get worse. There’s no cure,” he said.

Oppegard said he’s heard stories of coal companies in both ends of the state cheating on dust monitoring throughout his 38 years representing miners.

“It’s not an isolated incident,” Oppegard said of the allegations involving the two mines.

Coleman, the federal prosecutor, said he stressed at a news conference on the case that miners need to help guard their own safety and that of co-workers by reporting problems if they see them.

Coleman also said that while most coal companies operate within the law, the ones that might be tempted to engage in wrongdoing should consider the very real possibility of being prosecuted.

Those indicted Wednesday were Charley Barber, superintendent at the Parkway mine; Brian Keith Casebier, safety director at Parkway; Steven Demoss, the assistant safety director; Billie Hearld, a section foreman at Parkway and Kronos; Ron Ivy, safety director at Kronos; John Ellis Scott, who worked in the safety department at Parkway; and Dwight Fulkerson and Jeremy Hackney, section foremen who did dust sampling.

The conspiracy charge carries a top penalty of five years in prison.

Armstrong Coal declared bankruptcy after the period covered in the indictment from January 2013 to August 2015.

The Parkway mine is closed but the Kronos mine is open under new ownership.

The prevalence of black lung among miners went down significantly after Congress approved laws designed to limit miners’ exposure to dust in 1969, but there has been a resurgence in the disease in Eastern Kentucky and nearby areas in recent years.

There have been fewer cases reported from Western Kentucky, but it can take years for the disease to manifest.