"The town is the site of a toxic contamination that is unprecedented in American history," wrote Mark Levine of Libby, Montana, in his 2001 'Men's Journal' article "Killing Libby." At the time, environmental investigators had only begun to tap the full extent of the problem, but the culprit was clear: The processing of vermiculite ore from a local mine had released huge plumes of asbestos into the air for decades. Miners were dying early; their families were showing up at doctors' offices with persistent coughs. "An astounding one-third of Libby's residents are believed to have contracted asbestos-related lung disease," wrote Levine. Adding to the tragedy was the belief that W.R. Grace, the company that had operated the mine since 1963, had long known about the hazards. As one EPA scientist said at the time: "This was deliberate murder." Eleven years later, Levine returned to see what had become of the troubled town.

There is mountain time and there is human time, and somewhere in the purgatorial provinces between them sits Libby, Montana, a town of 2,600 that is ground zero in the vastest story of toxic contamination in U.S. history. The remoteness of this place, 110 miles west of Glacier National Park, is as striking as the severe beauty of the surrounding Cabinet Mountains. Libby can come across, at first glance, as a kind of rough-hewn Shangri-la, cut off from the upheavals of the world beyond its valley. Eleven years ago, I traveled there at a moment when it was beginning to grapple with the extent to which a local vermiculite mine, operated from 1923 to 1990, had doused the town with a virulent form of asbestos being blamed for the deaths of more than 200 residents.

I returned this winter to take stock of how the town and its people had progressed – if that's the right word – during the interim. The town I encountered in 2001 was a place of fear and intense division; many people seemed to blame their problems on a woman named Gayla Benefield. Benefield had been agitating for 27 years to bring attention to the contamination that she claimed had killed her parents and many others in Libby. I called her as soon as I returned, and to my surprise she suggested that we meet in a public place. We settled into a booth at Antler's Restaurant, and she started in chattily. "Don passed away," she said, filling me in on people I had previously interviewed. "Mike went on oxygen, and went downhill quick. His kids moved him away. Jimmy died of cancer. And Les, of course" – she took a sip from her mug of Diet Coke – "well, you missed the greatest funeral ever in Libby." For years, Benefield had received threats and anonymous calls urging her to leave town; old friends saw her in the supermarket and walked the other way. "Oh, all that's changed," she said. "Every once in a while people even come over and thank me."

Benefield's efforts brought an emergency-response team from the Environmental Protection Agency to Libby in November 1999. The EPA confirmed that Libby's vermiculite ore was laced with naturally occurring asbestos fibers, and that for years the mine had released a cloud of as much as 5,000 pounds of asbestos each day. The agency found the stuff everywhere: Piles of contaminated material had been kept at the edge of Little League ball fields, where children played in it; the high school track was surfaced with it; people collected it from depots in town and used it to improve the soil in their gardens; the forests where people hunted, fished, and gathered firewood were so contaminated that asbestos was braided into tree bark. After a federal agency administered screening, more than a thousand residents learned they had scarring on their lungs – an early sign of chronic, debilitating, irreversible asbestos-related disease. Benefield herself was one of 30 members of her extended family to be diagnosed with lung abnormalities. Libby had suffered a contagion.

Many residents refused to believe it. Although documents suggested that W.R. Grace, the conglomerate that owned the mine, had long been aware of the asbestos, the company had been a major benefactor of the community, and loyalty ran high. People who claimed to be ill were accused of malingering. In 2001, Benefield had introduced me to a friend of hers named Les Skramstad. Skramstad was forthright, charismatic, and a great storyteller, despite the fact that he gasped for air as he spoke. As a young man he had worked at the mine for just under three years, beginning in 1959. Not long before I met him, his family had been screened for lung abnormalities. "If it had just took the lives of us miners, that would have been bad enough," he had told me. "But I carried it home and gave it to my wife and three of our five children." Skramstad was one of the few locals who fought W.R. Grace in court and won. At the time, he was widely derided for inventing his illness to scam the company.

"The people who said we were blowing this out of proportion, they're quiet now," Benefield said. "There's hardly a soul in Libby at this point who doesn't have a friend, relative, or neighbor who's been afflicted by this." Indeed, for Benefield, Libby is a cautionary tale about the consequences of trusting too much – in a company whose profit motive might outweigh its commitment to safety and in government regulators who get too cozy with the industry they're supposed to patrol. Now 68, she was diagnosed with bladder cancer two years ago. She said her respiratory health is good – that of her husband and 47-year-old daughter, less so. She has ceased her activism. "I'm done. The real victory was letting them know I was too damn stubborn to kill." Les Skramstad contracted mesothelioma, a rare and incurable cancer almost invariably associated with asbestos, and died in January 2007.

Over the past decade, Libby has emerged as a living laboratory for the study of toxic exposure. I returned to visit Dr. Brad Black, medical director of Libby's Center for Asbestos Related Disease, or CARD. In 2001 he was the county's part-time public health officer, struggling to cope with the mysterious medical crisis that had been dumped at his doorstep. He had moved to Libby in 1977 to set up a pediatrics practice, and is now almost certainly one of the world's most experienced clinicians in a grim, specialized field. "You end up doing things you didn't expect," he said. "This thing has just kept on getting bigger." The clinic has 4,000 patients, half of whom have shown evidence of asbestos-related changes in their lungs. Black believes there could be 20,000 others who have gotten sick from Libby asbestos, or who will. (The disease can remain latent for up to 40 years.) Libby's rate of asbestosis is estimated to be 40 to 80 times higher than the population at large; its rate of mesothelioma is 100 times the norm. Asbestos-related disease, which, Black told me, slowly scars the lung, is frequently accompanied by chronic and severe pain. "I've seen couples in their early forties come in here crying because the pain makes it impossible for them to have sexual relations," Black said. "No one expected to have to deal with this."

The EPA team that arrived to deal with Libby's situation in late 1999 had the heroic sheen of scientist-cowboys, come to rescue the town from its plight. The EPA remains, but it has come to assume a workaday presence as it tries to get to the end of what can seem to be a bottomless problem. Mike Cirian, an engineer and the on-site manager for the EPA's Libby work, has been in town since 2005. "This isn't your typical cleanup," he said. "It's an entire community. People live in it." The boundaries of the cleanup encompass approximately 180 square miles. Close to one-third of Libby's properties were found to have vermiculite in their soil; air tests determined that gardening, mowing lawns, and using leaf-blowers were hazardous activities. According to Cirian, the EPA has decontaminated 1,600 residences, at a rate of 130 to 150 a year. It has removed 25,000 cubic yards of vermiculite insulation and 1.2 million tons of soil. The air in downtown Libby had 10,000 times as much asbestos in it when the EPA arrived as it does now. In 2008, the EPA negotiated a settlement of $250 million, its largest ever from a polluter, from W.R. Grace. Still, the agency has spent that and more in Libby – $420 million so far – and it no longer knows when its job will be done.

Cirian drove me around to show me some of the EPA's work. We passed an old Victorian house that had broad tubing running from its exterior to ventilation machinery on the lawn. We passed a row of three bungalows. "Did that one, did that one, did that one," Cirian said. At the edge of downtown, he steered his truck toward a large, muddy field, buzzing with heavy equipment, on the banks of the Kootenai River. After years of dispute, Libby and the EPA had agreed to reclaim this land for a 17-acre riverfront park to open this summer. It is the former site of the contaminated ball fields, where generations of Libby's children had played.

In 2001, I interviewed a man named Alan Stringer, a former superintendent of the mine and W.R. Grace's last remaining employee in Libby. He struck me as anxious and frustrated. He had been returned to the town for an unenviable public-relations role, and the tortuous explanations he offered on behalf of the company came across as wan and half-hearted. I was somewhat saddened when I learned, in 2005, that Stringer had been named as a defendant in a federal prosecution of W.R. Grace and former executives and managers on charges of conspiracy, wire fraud, violation of the Clean Air Act, and obstruction of justice – essentially, of knowingly contaminating Libby and covering it up. The prosecution, though, faced overwhelming challenges. W.R. Grace, which entered bankruptcy in 2001, nonetheless spent $160 million in its defense and litigated elements of the case up to the Supreme Court. There were years of pretrial delays. Before he could face a jury, Stringer died of cancer.

When the case was finally tried, in 2009, W.R. Grace's team of nearly three dozen lawyers raised questions about whether the vermiculite was actually asbestos and whether the diseased residents had been largely misdiagnosed. They convinced the judge to curtail the testimony of the EPA agent who had first discovered the contamination, and discredited one of the prosecution's lead witnesses, a former W.R. Grace executive who claimed the company was fully aware of the dangers. Following 11 weeks of testimony, the jury returned a not-guilty verdict after less than two days of deliberation.

"Everybody here was really disappointed by the verdict," Doug Roll, a former Marine who is currently Libby's mayor, told me. "No – that's not a strong enough word. With all the damage that company did, to see them get off scot-free just made people mad."

Roll, who has been mayor since 2009, runs an auto-repair shop down the street from Libby High School. The sign on his office door reads repair and despair. The sentiment is apt. If people in Libby had hoped for satisfaction from the justice system, what they got instead was a reminder of their own powerlessness. As Roll is intent on pointing out, though, asbestos isn't Libby's only problem, or even its most pressing one. "There's just no jobs here, nothing," he said. The timber industry, which once employed thousands in the area, has all but shut down. Lincoln County, which includes Libby, has Montana's highest unemployment rate, at 18.1 percent, compared with the state average of 6.5 percent. Close to one in five residents lives below the poverty line. "My best friend left a few months ago to work in the oil fields in North Dakota," the mayor said. "I probably know 10 guys who've gone there."

I asked Roll whether Libby could ever be made whole. "We've been down and beaten up," he said. "We've been angry so long it's hard to maintain the anger. Maybe things are going to turn around. Closure for us – that's probably 30 or 40 years down the road, when the town is all cleaned up and we don't have any more sick people."

That can seem like a fantasy, belonging to another life, another place. Although the EPA has assured residents it will not leave Libby before the cleanup is done, the agency's early drafts of toxicity studies of Libby asbestos – attempting to measure how much exposure to the fiber will put human risk at health – have suggested to some that even very low levels of exposure are potentially hazardous. This is a problem for the entire country – insulation containing Libby asbestos is estimated to be in 30 million homes in the U.S. – but it poses a particular threat to the existence of the town. As one person told me, "Maybe Libby can never be clean enough to be safe."

During my return, I often thought of a man I interviewed back in 2001. He was in his early thirties and in obvious distress. He had been diagnosed with lung abnormalities, and feared for his future. He lived in the woods outside town. The woods, he said, were the only place he ever felt he belonged. Hunting was his passion: He'd trained himself in taxidermy, and his handiwork – bighorn sheep, black bear – stared out at us as we spoke. He had a newborn son, he told me, and he dreamed of teaching him about the woods, of going hunting with him one day. But now he worried it would never happen.

I didn't remember this man until I went back to Libby this year. I asked around, but wasn't able to find him – after all, a long time has passed. I have young sons of my own now, so I think I can better understand what he must have been going through. The woods of western Montana would be a rare place for a child to grow up, for a man to grow old.

I hope he's doing well, wherever he is.