Haze blankets the Portland skyline earlier this summer. Credit: Troy R. Bennett / BDN

Maine and other New England states have raised concerns for years about how industrial air pollution from states to the west has affected the region’s air quality.

But as global climate change continues to play havoc with weather patterns around the world, smoke from western wildfires also is having an impact on Maine as the resulting particle pollution blows east.

The haze that settled over Maine and other New England states on Monday and Tuesday stems from smoke from wildfires in western Canada, which along with others in the western U.S. have burned nearly 9,000 acres on both sides of the border so far this year. The fires have affected air quality across the continent as winds have carried plumes of smoke east, prompting the Maine Department of Environmental Protection to issue a health advisory for people with breathing difficulties or who might engage in strenuous outdoor activity while air quality is poor.

Despite being thousands of miles away, large wildfires that have flared up in the West have caused dim skies in Maine in at least each of the past two summers. Closer to Maine, smoke from summer wildfires in Quebec has blown across the border multiple times in recent decades, creating brilliant orange sunsets while driving many people indoors in search of better air.

Joe Hewitt, lead forecaster for the National Weather Service in Caribou, said that the agency partners with the Maine Department of Environmental Protection in issuing the alerts. He did not have a number for how many wildfire-related air alerts have been issued in Maine in recent years, but estimated that Maine has roughly two air quality alerts each summer, either for wildfire smoke or for elevated ozone levels, which are driven primarily by pollution.

For wildfires out west, Hewitt said, the wind patterns have to line up just so to transport the haze to Maine. Smoke from fires in Quebec can drift into Maine at lower altitudes, but smoke from western fires have to get up into what he called “transport” winds between 10,000 and 20,000 feet to have an impact on the East Coast.

“That smoke can travel quite a distance,” Hewitt said.

As large wildfires farther west become more common due to changing weather patterns that are making conditions in that region hotter and drier, hazy days in Maine stand a good chance of becoming more common, according to Sean Birkel, a research assistant professor at the Climate Change Institute at the University of Maine and Maine’s state climatologist.

“Much of the western U.S., especially the Southwest region, is in a prolonged drought that began in the early 2000s,” Birkel said. “The western U.S. is expected to get drier as the climate warms, and with that there is greater likelihood of large fires. Some weather patterns produce long-distance transport that can bring smoke from those fires to the sky over Maine.”

Wildfires occur in Maine too, and seem to be happening more frequently the past few years, though persistent rainfall this month has reduced drought levels and kept the current danger of wildfires low. As of Tuesday, more than 570 wildfires had occurred in Maine so far in 2021, which is well ahead of the state’s annual average of 545 from 2016 through 2019, according to the Maine Forest Service.

Haze caused by wildfires in the western U.S. and Canada creates an orange glow around the setting sun outside the National Weather Service office in Gray on Monday. Credit: Courtesy of National Weather Service

It has been decades since a Maine wildfire burned more than 1,000 acres, and those that have occurred more recently generate far less smoke than the much larger wildfires that flare up each summer in the West. The 1,030 acres statewide that burned last year in Maine’s 1,150 wildfires amount to roughly half of 1 percent of the nearly 200,000 acres that, as of Tuesday, had burned in the Dixie wildfire near Chico, California.

Whether climate change will result in more wildfires in Maine is hard to predict, Birkel said.

“Maine’s climate is projected to get wetter, but with warmer temperatures there is also expected to be more evaporation and an overall intensification of the hydrologic cycle, meaning more extremes,” he said. “It is so far unclear how these combined factors will affect the future occurrence of drought and wildfire in the state.”

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....