Severe wildfires in Canada blanket the northeastern United States in a dystopian haze, souring the air, turning skies yellow-gray and prompting vulnerable populations to stay indoors.

The effects of hundreds of active fires raging across Canada’s western provinces all the way to Quebec could be felt as far away as New York and New England, obscuring the city’s skyline and sore throats. .

US authorities have issued air quality alerts. In the Great Lakes region, from Cleveland to Buffalo, there was haze and smoke from wildfires.

The mixed haze and smoke that hung over New York for much of Tuesday thickened late in the afternoon, obscuring New Jersey across the Hudson River and turning the sun into something of a red orb at sunset. In the Philadelphia area, the setting sun gave lavender hues to the fog.

Sal and Lilly Murphy of Brooklyn likened the burning aroma to that of a campfire. They said they could smell it even in enclosed spaces, in a restaurant in Manhattan, and as they left, they saw that the sky looked like it was about to unleash a storm, but it wasn’t raining. Lilly put on a mask to protect herself.

“It’s kind of scary,” Sal Murphy said.

Smoke from the Canadian fires has been spreading across northeastern US states for weeks, but in most places has not become apparent so far.

New York Governor Kathy Hochul said the hazy skies were “hard to ignore” on Tuesday, and New York City Mayor Eric Adams encouraged residents to limit outdoor activities “to the bare minimum”.

Here’s an overview of what’s going on and some suggested precautions for dealing with the fog.

WHAT IS HAPPENING?

Since last month, the United States has been receiving smoke from wildfires in Canada. The most recent, near Quebec, have been active for at least several days.

The US Environmental Protection Agency said haze, reduced visibility and the smell of burnt wood are likely, with smoke lingering for a few days in northern states.

“It is not uncommon for us to have smoke from fires in our area. It’s very typical of northwestern Canada,” said Darren Austin, a meteorologist and air quality specialist with the Rhode Island Department of Environmental Management. But normally the smoke would stay in the air. air and did not affect the health of the population, he stressed.

The fires in the Quebec City area are large and relatively close, 500 to 600 miles (800 to 970 kilometers) from Rhode Island. And they follow those recorded in Nova Scotia, which prompted a brief poor air quality alert on May 30, Austin added.

Jay Engle, a National Weather Service meteorologist based in Upton, Long Island, said the wind path that brought haze and smoke to the New York area could continue for days. Of course, he added, the main reason for this is the fires themselves. If they are reduced, the fog will be too.

WHAT IS THE MOST WORRIED?

Air quality flaps are caused by a number of factors, including the detection of fine particle pollution, known as “PM 2.5”, which can irritate the lungs.

“In our upper airways, we have defenses to trap larger particles and prevent them from descending into the lungs. These particles are just the right size to break through these defenses,” said Dr. David Hill, a pulmonologist in Waterbury, Connecticut, who serves on the national board of directors for the National Lung Association. “When these particles reach the respiratory space, they cause an inflammatory response in the body.”

Trent Ford, an Illinois State climatologist, said weather conditions in the Upper Midwest, which created hot, dry weather, allow small particles to easily travel hundreds of kilometers (miles) from active fires in Canada and stick around for days.

“It’s a good example of the complexity of the climate system, but also how it’s connected,” Ford said.

WHO SHOULD BE CAREFUL?

Exposure to high levels of fine particulate pollution can affect the lungs and heart.

The air quality alerts warn “sensitive groups”, a broad category that includes children, the elderly and people with lung conditions such as asthma and chronic obstructive pulmonary disease, or COPD.

Children, who are often encouraged to play outside, “are more likely to smoke for a number of reasons,” said Laura Kate Bender, associate vice president of the National Lung Association. “Their lungs are still developing, they are breathing more air per unit body weight.”

WHAT CAN WE DO NOW?

Now is a good time to put off gardening and outdoor exercise. If you go out, consider wearing an N95 mask to reduce exposure to contaminants.

Stay home and keep doors, windows and fireplaces closed. It is recommended to set the air conditioning with a recirculation program.

“If you have filters in your home’s HVAC system, you need to make sure they’re up to date and of high quality,” Hill added. “Some people, especially those with underlying lung or heart disease, should consider investing in air purifiers for their homes.”

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Associated Press writers Katie Foody in Chicago and David B. Caruso and Deepti Hajela in New York contributed to this report.