Last December, Michael Spence, Montana's chief medical officer, got an unexpected piece of mail. It was a Christmas card from the management of the Super 8 motel in Libby, Montana--a reminder of just how much time he had spent in the small town more than 300 miles away from his office in the state capitol of Helena.

Before November 1999, most people in Montana knew of Libby, population 2,890, mainly as the childhood home of Governor Marc Racicot. That changed when the Seattle Post-Intelligencer published an article detailing asbestos contamination in the town, site of a vermiculite mine. Within days, state health officials had descended on Libby, and Spence has been a part-time resident ever since.

Libby is now considered to be the country's worst instance of residential exposure to a hazardous material. Vermiculite--a mineral used for insulation and fertilization--is not dangerous by itself. But the vermiculite in Libby was laced with a particularly insidious form of asbestos. As many as 30 percent of the area's 6,000 residents have shown symptoms of lung disease, and 200 have died of asbestos-related illnesses. Although the mine closed 10 years ago, asbestos can sit in the lungs for up to 50 years without causing symptoms, so the ultimate toll is still unknown.

Spence, who is 63, spent 22 of his life years teaching medicine, but environmental contamination was never one of his specialties. His training was in obstetrics and gynecology. Still, he did have experience with medical crises. In Philadelphia, Spence had run the largest clinic in the world for HIV-infected women, and a clinic for pregnant cocaine users. In Baltimore, he ran STD clinics for the city health department.

But as he reached his mid-50s, Spence was ready to move on. When a friend called in 1996 and told him that the state of Montana needed a medical chief, he jumped at the chance. About six months later, he was driving a Ryder truck from Philadelphia to Helena.

It wasn't just the scenery that changed. As chair of the OB-GYN department at Hahneman University in Philadephia, Spence supervised 100 employees. Now, he jokes, "I'm the highest paid typist in Montana."

He's accomplished a great deal. In addition to handling standard public health concerns, Spence expanded a program to educate legislators about health issues. "Education is the kind of business I've been in all my life," he says. "I try to make sure they understand what we're trying to accomplish."

The dominant issue for most of Spence's tenure in Montana has been the Libby case and its consequences. Asbestos was previously considered dangerous only for those with direct exposure, but Libby has proved that theory wrong. When the vermiculite was heated in a furnace during mining, much of the asbestos turned into a dust cloud that distributed itself over the town. Many who are now sick neither worked in the mine nor had family that worked there.

There's no simple cure for the problem, but Spence and his colleagues have done everything they can to ameliorate it. Patients thought susceptible to lung diseases such as pneumonia are given flu shots and carefully monitored. Health care services are provided for the uninsured. And Libby is the site of the nation's largest public-health testing program, with Spence and others evaluating more than 7,000 people in order to understand just how many were affected by the toxic mixture. For his work, Spence was recognized by the Agency for Toxic Substances and Disease Registry, a division of the Centers for Disease Control and Prevention, with the national Special Service award.

The effort to fully understand what happened at Libby, and to prevent it from happening elsewhere, will not be completed for many years. Spence wants to stick around to help coordinate that process, even if that means a few more nights in budget motels. "Montana," he says, "is where I'm going to be for the rest of my career."