Air quality impacts of wildfire go beyond visible smoke. In a year that Colorado has seen 17 fires over 1,000 acres, with six of those large wildfires having started in the last month, air quality is top of mind for many people. The Sopris Sun spoke with air pollution and environmental health expert Michael Petroni, PhD, to learn more about how wildfires affect air quality and what people can do to protect themselves.
Petroni did his graduate work at Syracuse University and State University of New York Environmental Science and Forestry, but has family ties to Colorado and has been visiting the Rockies since he was a child. He has worked with ProPublica on air pollutant exposure risk factors and spent over three years with the United States Environmental Protection Agency’s Sustainability and Pollution Prevention Branch. Petroni describes his motivation for his work as “making invisible environmental exposures visible and useful to regular people.”
Petroni says that self-protection from smoke and other transient air pollution is all about timing.
“The most useful thing I can tell people is that smoke is forecastable,” he said, “and the window before it arrives is when you have the most leverage. Most people react once the sky is already orange — the payoff is in acting a day ahead.”
Colorado’s location in North America means that winds often move northeast across the state, though they can sometimes move due north or northwest when powerful pressure systems push up from the Gulf of Mexico. Even when the state does not have active wildfires, smoke can move through from Utah, Nevada, Arizona and New Mexico.
Petroni recommends having a clean air plan for bad smoke days.
“When you know smoke is inbound, set up one ‘clean air room’ — usually a bedroom — with a HEPA purifier before the air turns. The actions compound, sealing windows alone cuts indoor levels roughly in half and adding HEPA filtration brings a room from hazardous to moderate inside the same house,” he said.
“Stage your N95 or KN95 respirators where you can grab them, run your [ventilation or air conditioning] on recirculate with a good filter and reschedule anything strenuous outdoors,” Petroni continued. “Have a specific plan for the higher-risk people in the household — kids, older adults and anyone with heart or lung conditions.”
“The biggest misconception is that a bad smoke day is just a bigger version of a normal bad air day,” Petroni said. “They are not the same. Urban PM2.5 tops out around
55 µg/m3 on a rough day and ozone peaks are predictable; a nearby wildfire can push past 450 µg/m3, a qualitatively different exposure. Furthermore, evidence suggests wildfire PM2.5 may be more toxic per microgram than ordinary urban particulate.”
“The second misconception is that once the sky clears, you’re fine,” Petroni said. “The biology doesn’t reset that fast. Each heavy smoke event sets off lung and cardiovascular inflammation that can linger for weeks, and repeated seasons leave measurable, lasting changes. This includes lung function that never fully returns to baseline, accelerated cardiovascular damage, even emerging evidence of neuroinflammation. The clearest example is wildland firefighters, otherwise fit adults, who show elevated lung-cancer and cardiovascular mortality.”
Fortunately, there are multiple levels to protecting oneself during periods of poor air quality, according to Petroni.
“Reduce what you breathe in,” he said, take advantage of filtered indoor air, and use properly fitted N95. “Fit matters as much as the rating,” he continued. “Press the nose bridge and check for leaks.” He noted that “surgical and cloth masks do essentially nothing against smoke particles.” Finally, “Cut physical exertion, since heavier breathing drives particles deeper.”
“The part people rarely hear is that how you take care of your body matters too, because so much of smoke’s harm runs through inflammation and oxidative stress,” Petroni said. “Emerging evidence suggests an antioxidant-rich diet. This includes plenty of fruits and vegetables, omega-three fatty acids, which may help blunt some of that inflammatory response. Staying well hydrated supports your body’s clearance, and it’s worth going easy on alcohol during heavy smoke since it adds to the inflammatory load.”
And, apparently, cleaning after smoke is important.
“When the smoke clears, fine soot and ash don’t disappear,” Petroni said. “They settle onto surfaces inside and outside your home, and they’re not just burned wood. Wildfire and especially structure-fire residues can carry PAHs, heavy metals and other combustion byproducts. Ash from burned buildings can contain lead and asbestos. The hazard is that this settled soot gets re-suspended into the air you breathe every time it’s disturbed — walking across it, dry-sweeping or running a leaf blower.”
Petroni recommends using damp wiping and a HEPA vacuum rather than dry sweeping, wearing an N95 mask while cleaning, keeping kids and pets away from ash and avoiding tracking outdoor soot into the home. Petroni said that he recommends the WatchDuty app for tracking fire and smoke. He has also been developing his own app, PollutionProfile, which forecasts air pollutant exposure and offers guidance for managing such risks.