Washington, Chicago, Detroit have some of the worst air quality in the world: Updates

ARLINGTON, Va. − Smoke from wildfires raging in Canada engulfed more U.S. cities on Thursday − from the Midwest to the Northeast to the mid-Atlantic to the Southeast − leading to perilous air quality for millions and prompting warnings to limit outdoor time.

The unhealthy air shifted slightly south since Wednesday, and more parts of the country are being affected, National Weather Service meteorologist Bryan Jackson told USA TODAY. The federal government tracks and publishes searchable real-time results.

"Some places are having a repeat of yesterday, some are worse than yesterday," Jackson said, adding that the smoke moved into cities like Pittsburgh and Washington, D.C., starting Wednesday afternoon. The Canadian wildfires have burned a larger area than the state of Maine.

Washington, Chicago, Detroit among cities with worst air quality in the world

As of Thursday morning, the Washington, D.C., area, Chicago and Detroit were among the cities with the worst air quality in the world, according to IQ Air's Air Quality Index. In some areas, authorities discouraged people from exercising outside over concerns the pollution could damage their breathing, especially if they have asthma.

Sheryl Stein, a writer in Arlington, Virginia, went out Thursday morning to exercise at her local community center. She was planning to go for a walk outside afterward but decided against it because just the walk to her car left her coughing from the smoke. Stein has asthma, and she put on an N95 mask to protect herself

"It smelled kind of like a chemical barbecue," Stein told USA TODAY. "I saw more people with masks on today than usual."

A 10-minute walk with her dog, Paige, was all it took for Renee Powlette, who works in IT and also lives in Arlington, to get a headache.

“I felt a little scratchiness in my throat, too, which didn't happen the last time, a couple of weeks back when we had this bad air quality. I think this seems to me was worse than last time,” Powlette said.

Powlette is the president of her condo association and said they are keeping the shared pool closed Thursday.

Powlette wasn’t wearing a mask when she went out with her dog, but when she had to go back out again later in the day, she put one on. She’s going to stay indoors until the air gets better and keep walks short to protect herself and her dog.

Experts warn risks of smoke exposure

Experts warned that healthy people are also at risk of getting sick when the Air Quality Index reaches an unhealthy level. Health officials advised people to limit outdoor activities and prevent smoke from getting indoors by closing windows or running central air conditioning with high-rated filters.

"Until the fires are out, there’s a risk," Jackson told the Associated Press. "If there’s any north component to the wind, there’s a chance it’ll be smoky."

Symptoms of respiratory illness can be caused by small particles in wildfire smoke and polluted air, such as irritation of the eyes, nose, and throat; shortness of breath; coughing; and chest tightness.

“With degree to which we’re seeing pollutants in the air, people who wouldn’t otherwise have symptoms start having more symptoms," said Dr. Brad Gable, an emergency medicine physician for OhioHealth.

Cities in over a dozen states have issued air quality alerts

More than 120 million residents across the Midwest and East Coast were under air quality alerts Thursday, AccuWeather said. Cities in over a dozen states from Duluth, Minnesota, to Portland, Maine, and as far south as Atlanta issued Code Orange air quality alerts or worse Thursday, according to the weather service.

Jackson said Madison, Wisconsin, as well as Pittsburgh and Columbus, Ohio, are experiencing dangerous levels of air pollution Thursday, and numbers on the Air Quality Index scale are hovering around 200, or "very unhealthy."

Entire states, including New York, New Jersey, Maryland and Vermont were blanketed by the warnings Thursday, according to the weather service.

In West Virginia, a "special weather statement" has been issued for most of the state warning motorists of low visibility on roads and "hazy conditions" caused by a combination of the Canadian wildfire smoke and river valley fog.

Thursday is "the third straight day" of air quality alerts for some cities, including Chicago, Detroit, and Milwaukee.

Air quality index basics: How it works, what each color code means and how to stay safe

Conditions are not expected to widely improve Friday

Detroit, which was ranked as having the world's worst air quality on Thursday afternoon, expected to see conditions remain poor Friday, along with the southeast Michigan counties of Oakland, Macomb, Washtenaw, Wayne, St. Clair, and Monroe.

In Washington, D.C., and Chicago and, conditions were expected to improve from red to orange, indicating a lower risk for most people but reflecting continued concern for people with sensitivities.

AccuWeather meterologists said localized showers and thunderstorms may help improve the air quality around the Great Lakes region but some areas will see smoke through the holiday weekend.

Will the Canadian wildfire smoke ever end this summer?

Thanks to the ongoing wildfires in Canada, which show no sign of ending, smoky air is likely to be a regular occurrence down here in the U.S. throughout the rest of the summer, experts said.

"As long as those fires keep burning up there, that’s going to be a problem for us," Weather Prediction Center forecast operations chief Greg Carbin said. "As long as there’s something to burn, there will be smoke we have to deal with."

The unusual jet stream pattern, which continues to periodically funnel the foul, smoke-filled air over U.S. cities, shows no sign of changing or letting up.

"While the fires are ongoing, you can expect to see these periodic bad air days," University of Chicago atmospheric scientist Liz Moyer said. "And the only relief is either when the fires go out or when the weather pattern dies."

When will conditions improve even slightly?

Some parts of the Midwest could see improvements in the air quality on Friday, Jackson said. A southerly wind that's spreading west across the upper Midwest could clear some smoke, he said.

"That is supposed to push the smoke farther north and allow it to disperse moweekend, meaning smoke could linger over the U.S. for several more months.

Contributing: Thao Nguyen, Gave Hauari, and Grace Hauck, USA TODAY; Keith Matheny, Marina Johnson, the Detroit Free Press; Jack Nimesheim, Columbus Dispatch; The Associated Press

This article originally appeared on USA TODAY: Air quality updates: 3 cities among worst; when will it recede?