It’s been a rough news week for the state of Kentucky, and it’s not likely to get any better with the PBS Frontline exposé, Coal’s Deadly Dust.

The title holds certain truths to be self-evident, and it shouldn’t come as a surprise to anyone that coal mining, by its very nature, is dangerous, potentially deadly work. And the danger doesn’t end the moment the shift is over. The long-term health effects of a life spent in the mines are only now coming to light.

That there are long-term health effects won’t come as a surprise, either, given what we know now about smoking, bad diet choices, toxins in the air we breathe and any number of other existential health threats.

What is new is the likelihood that the coal industry — and government agencies — knew about the long-term effects of being exposed to coal dust, but did next to nothing to warn miners of it. As the program, produced in cooperation with NPR, notes in its opening moments, this isn’t an issue limited to Kentucky but also Virginia, West Virginia, and Pennsylvania — in short, wherever there are coal mines and coal miners to mine them.

Black lung disease was thought to be in decline as recently as two years ago, but as an investigation by NPR — and a tip to NPR reporter Howard Berkes, who had been working on the issue of black lung disease for six years — reveals, an outbreak of an advanced form of black lung disease happened just two years ago. Why? And why did no one know about it at the time?

Coal’s Deadly Dust asks that age-old question that dogs alleged cover-ups everywhere: Who knew what, what did they know, and when did they know it? And, more importantly, why didn’t they tell anyone?

Coal’s Deadly Dust talks to a former miner with an advanced stage of black lung disease as he ruminates about missing quality time with his young family because he put in 12- to 18-hour shifts in the local mine, to make ends meet and carve out a better future for his loved ones. Dry statistics are one thing, but first-person witness testimony is always more compelling, especially when the story is as sad and affecting as Greg Kelly’s (right), an otherwise fit family man who now struggles with simple, everyday tasks.

Again, there’s nothing new here — Coal’s Deadly Dust recalls the worst elements of Love Canal and the Flint, Michigan water crisis, cover-ups that are inevitable whenever environmental regulations are loosened, and industries are allowed to regulate themselves. There’s a pattern here.

The difference this time is that the problem was supposed to have been resolved. Black lung disease was believed to have been all but eradicated, remember. The figures show that the disease was in decline over a period of several decades. So why did Berkes get a tip out of the blue that coal miners appear to be getting an advanced form of black lung disease, at a younger age and more quickly than before? Why this, and why now? Those are the unanswered questions that form the core of Coal’s Deadly Dust’s story. Chest x-rays don’t lie.

Experts are unfashionable these days, but experts are expert for a reason. One epidemiologist tells Berkes that much of the testing and monitoring focused on working coal miners, for obvious reasons, but not recent retirees from the job, even when those retirees were in their 30s and 40s — much too young to walk away from a well-paying job for health reasons. “Horror, shock, I don’t know how many other words to use,” the epidemiologist tells Berkes, midway through the program. “I was really taken aback, not only that these cases were legitimate but just how severe they were. It indicated that we had a huge problem and we realized immediately that it wasn’t going to be isolated to a single clinic.”

More than 2,000 cases later, spread across four Appalachian states, it’s clear the problem is not isolated at all. Frontline and NPR reveal that some clinics are reporting “dozens of new cases” a month.

“For so many years these men extracted this coal,” an overwhelmed clinic director and former director of a black lung program in Stone Mtn., Virginia tells Berkes, “so that you and I . . . They paid the price so that we can have luxuries. I feel that America just forgot about it.”

Not easy viewing. But Frontline is the epitome of good, solid reporting in an era when so-called fake news is all the rage. Frontline is in the business of telling viewers what they need to know, not what they want to hear. And Coal’s Deadly Dust is a prime, primetime example of that.

Frontline "Coal’s Deadly Dust" airs Tuesday on PBS at 9 p.m. ET (check local listings)