Wildland firefighters don’t care to be called “smoke eaters” anymore, but smoke is what’s on their menu.

And it’s on the minds of Joe Domitrovich and Joe Sol at the U.S. Forest Service’s Technology and Development Center in Missoula, where they’re studying just how much smoke a firefighter can eat – or breathe – before health issues start to hurt performance.

The Joes, as they’re known at the center, are in the first year of a five-year analysis. Domitrovich has a doctorate in exercise physiology and Sol has a master’s degree from the University of Montana.

“We’re also both experienced firefighters,” Sol said. “We understand the culture and we know how to stay out of the way. It’s made it easier to get volunteers.”

Questions about smoke exposure started circulating in 1988, when the summer-long conflagration in Yellowstone National Park got people wondering if there was a health and safety issue from breathing fumes shift after shift. But the technology wasn’t ready to provide any good answers.

Now the T&D Center can provide carbon monoxide dosimeters smaller than a deck of cards (or a pack of cigarettes) that clip onto a firefighter’s shoulder strap. The little devices pump in air and calculate CO levels minute by minute.

Volunteers in the study also carry little activity monitors and cameras. That allows Domitrovich and Sol to crunch data for the whole day’s activity, comparing smoke levels when the firefighter is in camp, traveling to a perimeter, working on active flame fronts or performing mop-up work.

Current Occupational Safety and Health Administration standards say workers can endure about 50 parts per million of CO during an average eight-hour shift, with short-term exposure of up to 200 ppm. But firefighters often work 14- to 16-hour shifts, and then may return to a base camp that’s shrouded in smoke.

That’s different from the U.S. Environmental Protection Agency’s recommendations for air quality that the Missoula City-County Health Department reports on smoky days. Those standards are aimed at pollution levels that could affect elderly or infirm people, while the OSHA standards assume the subject is an otherwise healthy working adult.

One unexpected result of the study showed where smoke exposure tends to be worst. It’s not in the roaring inferno of a wildfire perimeter, but the cooler mop-up stage when firefighters are digging up smoldering stumps and soaking hot spots that most smoke gets inhaled.

“There’s a continuum of risk in firefighting,” Domitrovich said. “There’s hazard trees and driving and the fire itself, and then there’s smoke. You’re managing all of these minute by minute.

“But we’re also looking at what happens to firefighters over the course of a career. Carbon monoxide breaks apart quickly, but particulates stick around in the respiratory system for much longer. Our lungs are completely over-built, which is great. After fire season, we’ll typically see a fall in performance and then recovery. They get time over the winter to return to preseason (strength) values. But how many times can you recover, before the damage starts to be permanent?”

They also want to know how firefighters’ mental functions change with smoke exposure. They give volunteers tests before and after shifts in pattern-recognition, decision-making and other brain-teasers.

One tricky part of the study is the social nature of wildland firefighters. They tend to be young, mobile and part-time, which makes it difficult to find them years after they’ve left for new careers. Another challenge is the location of fires. Does a California wildfire burning in creosote bush and poison oak produce the same smoke components as a Montana fire in lodgepole and spruce?

Then there’s what to do about it. Nobody expects a new OSHA rule prohibiting firefighters from working on smoky days. The study hopes to provide more practical recommendations, like understanding the difference between direct-attack smoke and mop-up smoke, or how air disperses in spring fires compared to summer events.

“The EPA has done lots of work on smoke effects for the public, and OSHA does similar things for workers,” Domitrovich said. “We’re trying to stay in the worker environment. Although as a firefighter, I don’t like going home to breathe more smoke, either.”

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