A thousand-mile plume of toxic wildfire smoke from the Midwest and southern Ontario is turning Maine skies pink and blanketing the state with tiny dust particles that pose a health threat to residents.

The current haze has been thick enough to occasionally block out the sun and lower the local temperatures by 10 degrees, according to Derek Schroeter, a meteorologist with the National Weather Service office in Gray.

The thick smoke plume measures roughly 1,000 miles long and 250 miles wide, Schroeter said.

Across most of Maine on Tuesday and Wednesday, wildfire-related air pollution was at a moderate level of concern, according to the U.S. Air Quality Index. Conditions were projected to remain at that level Thursday.

Wildfire haze has become a new, dangerous reality for New England summers. Experts warn that climate change is fueling more frequent faraway fires, brewing up a toxic soup of chemicals that, given the right prevailing winds, can end up in Maine.

Wildfire smoke is a complex mix of gases and fine dust that can be less than half the size of a human red blood cell. The smoke can carry heavy metals or carcinogens like benzene released when fires consume buildings, electronics and cars.

These invisible threats are transported to Maine by powerful atmospheric currents.

The white-hot wildfire smoke rises until it hits the jet stream, a 40,000-foot-high wind that carries weather systems west to east. During an active fire season, the jet stream blows smoke in a concentrated plume straight toward the Northeast.

As of 2023, the prevailing winds have been directing more and more wildfire smoke to New England, according to David Madore, the Maine Department of Environmental Protection deputy commissioner and agency spokesman.

When the haze descends, either because of wind or because it cools, it can trigger a string of health issues, including some that can be felt right away and some that build over years, said Gail Carlson, an associate professor of environmental studies and the director of Colby College’s Buck Lab for Climate and Environment.

The smallest smoke particles bypass the body’s natural defenses in the nose to reach the lungs, Carlson said. From there, the particles can enter the bloodstream, causing cellular damage and inflammation throughout the body, and can even become lodged in your brain.

Inhaling wildfire smoke through acute exposure to high doses or steady doses over a long time can cause respiratory problems, including COPD, and pregnancy complications, like low birth weight, and is linked to heart attacks, strokes and dementia, Carlson said.

Maine is vulnerable because of its aging population and array of industries that keep workers outside, like logging and farming. Many Maine homes lack air conditioning, forcing people to leave windows open and draw microscopic pollutants directly into their living spaces.

Mainers can take simple steps to shield themselves from this far-reaching threat.

To protect yourself, the Maine Public Health Association advises keeping windows and doors closed as much as possible. If you do not have an air purifier, the MPHA urges a DIY solution: taping a high-efficiency filter to the back of a box fan to scrub the air inside your home.

Carlson, who is a member of the science panel advising the Maine Climate Council, said that Maine residents should not have to endure these smoke-tinged, bad-air-quality days as isolated events, but should demand policymakers address the root cause of the problem.

“If we are going to raise the concern enough to tell people to stay inside, stay cool and keep windows closed, we ought to do something about the ultimate cause: climate change,” Carlson said. “We keep burning fossil fuels at the pace we’re going, our air is only going to get worse.”