Smoke from Canadian wildfires created unhealthy air quality conditions for vulnerable people in northern Maine on Wednesday, an indicator of how the climate-driven spike in the frequency and intensity of wildfires can threaten even those who live far from the flames.

Scientists say wildfires also are amplifying climate change. The wildfire flames destroy large swaths of carbon-storing forests, bogs and vegetation, and the smoke from those fires contains toxic black and brown carbon emissions that absorb sunlight and convert it to heat.

APTOPIX Canada Wildfires

Smoke from the McDougall Creek wildfire fills the air and nearly blocks out the sun as people take in the view of Okanagan Lake from Tugboat Beach, in Kelowna, British Columbia last month. Darryl Dyck/The Canadian Press via AP

Colby College assistant chemistry professor Greg Drozd and his students are studying brown carbon: how long these aerosolized molecules stick around in the atmosphere cranking out heat, and at what rate.

“There is certainly a feedback loop – climate change leads to more wildfires and wildfires lead to more warming – but what’s important to consider is the magnitude of that feedback,” Drozd said. “If they don’t last that long (in the atmosphere), or stop absorbing light, we don’t need to worry much.”

But Drozd’s preliminary research suggests that brown carbon could linger in the atmosphere for much longer than previously believed. And while it absorbs less light than black carbon, brown carbon is four times more abundant in wildfire smoke.

Brown carbon loses absorptivity over time in a process that is known as photobleaching, something Drozd likens to a car sunshade fading in the sun, but it loses less than might be expected. It may form new types of brown carbon. Some molecules, Drozd said, may even react to form compounds that absorb even more sunlight, and thus create more heat.


If these findings bear out across the other 100 or so molecules that make up brown carbon, climate models that factor a wide range of variables, including the impact of wildfires on climate change, may need to be updated to account for this difference, Drozd said.

Human-caused climate change is driving the increase in rising temperatures and droughts that make wildfire seasons longer and more severe across the United States, according to multiple studies and the U.S. National Oceanic and Atmospheric Administration.

While Maine will be impacted by the smoke produced elsewhere, and the resulting warming effects, Maine itself is not facing as much climate-driven wildfire risk as other parts of the country, said Aaron Weiskittel, a University of Maine professor of forest biometrics and modeling.

Maine’s moisture tends to be more evenly distributed throughout the year, which contains the ignition risk, said Weiskittel, head of UMaine’s Center for Research on Sustainable Forests. And Maine’s forests are not remote, so when wildfires do start, they are easier to contain here, he said.

Most importantly, the majority of Maine’s forestland is privately owned and well managed, unlike large forests of the western U.S., which are public and not as well managed, Weiskittel said. He learned about the U.S. West’s ticking wildfire bomb as a graduate student in Oregon 20 years ago.

While he’s not shocked by it, Weiskittel recognizes the West’s wildfire epidemic is a global problem.


“The wildfire emissions are a huge setback for achieving net zero and highlight the vulnerable nature of natural climate solutions,” Weiskittel said. “We do need to be more proactive and support policy that incentivizes good forest management.”

One of Drozd’s colleagues, associate professor of environmental studies Gail Carlson, elaborated on the health impacts of the particulate matter from wildfire emissions earlier in the summer, and the likelihood of it happening more often, when smoke from another Canadian fire reached Maine.

“Will this become more common? It is likely,” Carlson said in July. “What we are seeing are climate change impacts in the here and now. It’s important for people to realize that climate change is happening, and it’s affecting us now. This is not something far off in the future.”


The Maine Department of Environmental Protection has issued three wildfire-related air-quality alerts so far in 2023. The latest one declared unhealthy levels of particle pollution for sensitive groups in northern Maine from Tuesday night through late Wednesday night.

The dense ground-level plume of smoke from fires in Canada was expected to push the 24-hour average air quality above moderate for only a few hours on Wednesday, the DEP said.


Children, healthy adults who exert themselves and individuals with heart disease or respiratory diseases such as asthma, bronchitis or chronic obstructive pulmonary disease can experience reduced lung function, shortness of breath, coughing, throat irritation and chest discomfort.

Some actions that can help protect someone during periods of unhealthy air quality include avoiding strenuous outdoor activity, closing the windows and using a fan or air conditioner if indoors, and wearing a mask to reduce some of the particles inhaled into the lungs.

In addition to vulnerable people, sports coaches, elder care workers, nurses and others who are responsible for the welfare of vulnerable people impacted by poor air quality are urged to consider some of these precautions.

For more information, and to check to see if the smoke has cleared out Thursday morning, people can call DEP’s toll-free air quality hotline at 800-223-1196 or go to the DEP’s air quality forecast page.

Related Headlines

Comments are no longer available on this story