Canada is facing a series of intense wildfires that have spread from the western provinces to Quebec, with hundreds of wildfires. The smoke traveled to the United States, prompting a series of air quality warnings issued since May.

The US Environmental Protection Agency issued a poor air quality warning for New England on Tuesday, a day after parts of Illinois, Wisconsin and Minnesota received a similar warning. . Last week, US officials in southern Maryland, Baltimore, Virginia and Pennsylvania said they were affected by wildfires.

Here is a summary of what is being assessed and some suggested precautions:

WHAT IS HAPPENING?

Smoke from wildfires in Canada has been spreading to the United States since last month. The most recent fires near Quebec have been raging for at least several days.

The EPA said overcast skies, reduced visibility and a smell of burning wood were likely, and smoke would linger for a few days in New England.

“It’s not uncommon for us to get smoke from a fire in our area. It’s very common in northwestern Canada,” said Darren Austin, a meteorologist and senior air quality specialist with the Rhode Island Department of Environmental Management. But the smoke is generally in the air. air and does not affect people’s health, he said.

The fires in the Quebec City area are large and relatively close together, about 500 to 600 miles from Rhode Island. And they tracked the Nova Scotia wildfires, which prompted a short-lived air quality warning on May 30, Austin said.

WHAT IS THE BIGGEST CONCERN?

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

“We have defenses in our upper airways to capture the larger particles and prevent them from reaching the lungs. They are just the right size to overcome those defences,” said Waterbury pulmonologist Dr. David Hill, Connecticut, and member of the national board of directors of the American Lung Association “When these particles descend into the breathing space, they cause an inflammatory reaction in the body.

Trent Ford, the Illinois state climatologist, said atmospheric conditions in the upper Midwest, creating a hot, dry climate, allowed small particles to travel hundreds of miles from Canadian wildfires and to stay for days.

“It’s a good example of the complexity of the climate system, but also of its connection,” Ford said.

WHO SHOULD BE CAREFUL?

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

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

Children, who are often encouraged to go outside and play, “are more likely to smoke for a variety of reasons,” said Laura Kate Bender, The Lung Association’s National Assistant Vice President, Healthy Air. “Their lungs are still developing, they are breathing more air per unit body weight.”

WHAT CAN YOU DO NOW?

Now is a good time to postpone yard work and outdoor exercise. If you go outside, consider wearing an N95 mask to reduce your exposure to pollutants.

Stay indoors, keeping your doors, windows and fireplaces closed. It is recommended to run the air conditioner on a recirculation setting.

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

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Associated Press reporter Katie Foody in Chicago contributed to this story.