Here’s why there’s so much smoke in the air right now

Intense smoke blanketed the northeastern United States for a second day on Wednesday, turning the air a yellowish gray and prompting people to stay indoors and keep windows closed. Smoke was billowing from dozens of wildfires in several Canadian provinces.

Much of the air was in the “unhealthy or worse categories over parts of the mid-Atlantic to the northeast and parts of the upper Great Lakes,” according to an advisory issued by the Environmental Protection Agency on Wednesday evening. .

PICTURES: Skies over Canada and the United States clouded by dangerous wildfire haze

US authorities have issued air quality alerts in several regions and the smoke is expected to linger for days.

Conditions were particularly bad in parts of central New York, where airborne soot was at dangerous levels. In New York, officials said Wednesday that everyone should stay indoors. The conditions arrived late Tuesday afternoon, obscuring the view of New Jersey across the Hudson River.

Here’s a look at what’s going on and what’s in the smoke:

genesis of smoke

Unusually hot and dry weather that did not stop sparked the forest fires.

“May was just off the charts – record heat across much of Canada,” said Eric James, a modeling expert at the University of Colorado’s Cooperative Institute for Research in Environmental Science, who also does part of the National Oceanic and Atmospheric. Administration.

A warming planet will produce hotter and longer heat waves, creating bigger and smoldering fires, according to Joel Thornton, professor and chair of the department of atmospheric sciences at the University of Washington.

The fires in the Quebec region are large and relatively close, about 500 to 600 miles (about 800 to 970 kilometers) from Rhode Island and they followed wildfires in Nova Scotia.

“I don’t remember any fires of this magnitude in the last 10 years,” James said of the fires in Quebec.

Smoke from the fires in western Canada has been drifting towards the United States for weeks. But it was the recent fires in Quebec that produced the dangerous east coast haze.

Why does the smoke stretch so far?

Strong winds high in the atmosphere can carry smoke long distances, and it is common for large, violent fires to create unhealthy conditions hundreds of miles from where forests are burning.

But the right mix of circumstances had to align for smoke to blanket America’s major cities: a dry, hot spring led the way. Then the weather did the rest, said Bob Henson, meteorologist at Yale Climate Change Connections.

LEARN MORE: How to stay safe when the air outside is toxic

In Canada, air flows counterclockwise around a low pressure system near Nova Scotia. This sends air south over the fires in Quebec. There, the air picks up smoke, then heads east over New York State, carrying smoke to the east coast.

“It’s just a matter of trajectory,” Henson said. “Smoke goes where the wind takes it.”

This wind pattern is not particularly uncommon. But the confluence of events is.

“The timing of these weather conditions unfortunately overlaps with a situation that was ripe for large fires,” Thornton said.

Weather conditions change and the worst conditions should only last a day or two. Some smoke, however, could linger for a week or more, according to James.

What is smoke actually?

Although smoke looks familiar, it’s actually a complex mix of shapes, ranging from round to corkscrew under the microscope.

“It’s not just one type of chemical,” said Rima Habre, an expert in air quality and exposure science at the University of Southern California. “It could contain toxic gases, carbon and metals.” As it travels, Habré said, it also changes and may contain ozone.

Much of what we see in the air and measure are small particles, or PM 2.5. These are so small that they can go deep into the lungs, where oxygen enters your circulation.

“Most of the time we worry about the inflammation of the lungs,” Habré said, because of these high levels of pollution. But with climate change amplifying the fires, more and more, she says, she worries that more people will be exposed to less extreme smoke for weeks or months.

“Most healthy adults and children will recover quickly from exposure to smoke and will not experience lasting health effects,” according to the EPA advisory. But this is less true for a large category of people, including children whose lungs are still developing, the elderly, and people with lung diseases, such as asthma and chronic obstructive pulmonary disease.

Stay indoors, keep your doors, windows and chimneys closed, is the advice. Air conditioning on the recirculation setting can help filter out some particles, and air filters can remove many more.

Phillis reported from St. Louis. Associated Press reporters Katie Foody in Chicago and David B. Caruso, Deepti Hajela and Ingrid Lobet in New York contributed to this story.