Dozens of wildfires are burning in the Canadian province of Québec, and the smoke is so bad that it's causing air quality problems across large swaths of the U.S.
The National Weather Service said air quality has "plummeted" across the Northeast.
Officials from the Midwest to the East Coast and as far south as North Carolina are warning residents to take precautions as the hazy smoke floats south and poses a risk to public health.
Canada has been experiencing a particularly brutal wildfire season this year, as extreme weather is worsening in part due to climate change. Blazes have recently flared up across Alberta, British Columbia and Nova Scotia.
Earlier fires have also sent smoke into the neighboring U.S., and Canadian officials are warning that the country's wildfire situation may get worse as the summer wears on.
"This is a scary time for a lot of people, not just in Alberta, but right across the country, including in the Atlantic, the North and Québec, too," Prime Minister Justin Trudeau said at a news conference on Monday.
So far this year, there have been 2,214 wildfires across Canada, according to Minister of Emergency Preparedness Bill Blair. The blazes have burned 3.3 million hectares — or more than 8 million acres.
The country is currently battling 413 wildfires, 249 of which are categorized as out of control, and an estimated 26,000 people remain evacuated from their homes.
Across Québec, more than 150 fires are raging, many of which are burning out of control, according to the province's forest protection service. Authorities have restricted access to parts of the forest and closed some roads.
Though officials said they hope precipitation forecasted for later in the week will help suppress the fires, the blazes were still sending smoke into the U.S. on Tuesday.
The Environmental Protection Agency and state officials in New England were predicting that wildfire smoke would linger over the region for a few days.
Poor air quality alerts were in effect for all or parts of Connecticut, Massachusetts, New Hampshire, Rhode Island and Vermont.
New York issued an air quality health advisory Tuesday for fine particulate matter in many parts of the state, including the New York City metro area.
Some Midwestern states were under threat from wildfire smoke, with air quality warnings in states including Minnesota, Wisconsin and Indiana.
Southern states were also impacted. Charlotte, N.C., and nearby areas were under a code orange air quality action day on Tuesday.
According to AirNow, an air quality database maintained by several federal agencies, moderate air quality and air quality unhealthy for certain groups was also recorded in Pennsylvania, Ohio, Illinois, Michigan, and several other states.
"How concerned you should be has a lot to do with your own situation," Jeff Schlegelmilch, director of the National Center for Disaster Preparedness at Columbia University, told NPR.
Not everybody is equally vulnerable to poor air quality, he said. It can be especially harmful for certain groups, including those with lung and heart disease, the elderly and pregnant people. Poorer communities already at a higher risk for diseases that can be worsened by unsafe air are also less able to pay for protective measures needed to guard against exposure.
The severity of poor air quality can also vary, which is why the U.S. uses a color-coded systems to communicate how bad the air is in a certain place at a given time. Under the Air Quality Index, green indicates the best conditions while maroon is the worst.
Still, Schlegelmilch says everyone should heed officials' warnings about poor air quality. Common recommendations include staying indoors and using an air filter, wearing a mask like an N95 when outside and avoiding strenuous activities.
"If you've got a red alert for air quality, it's probably not the time to go out and go for that jog or go for that run," he said, "because you're breathing in more air and you're breathing in more air more deeply."
Schlegelmilch says people should treat poor air quality as an ongoing health concern rather than a one-off event, since extreme weather is only going to worsen in the future and even repeated exposure to low levels of poor air quality can have a cumulative negative impact on your health.
"I think it's really important that we sort of think of these things as we do any other type of health or hygiene process. It's a process. It's not one moment in time that we take a specific action and we're protected," he said.
"When the air quality is bad, we have to take some of these protective measures for ourselves, both for the short-term and the long-term."
