The Minneapolis skyline is barely visible from Bde Maka Ska due to Canadian wildfire smoke on Thursday. Credit: Ron Trenda | MPR News

An air quality alert remains in effect for all of Minnesota through Tuesday, as what the state Pollution Control Agency calls an “unprecedented” stretch of poor air quality continues to affect the region.

This story also appeared in Minnesota Public Radio News

On Thursday, an air quality monitor in St. Cloud recorded the highest particulate reading on record for Minnesota — 422 micrograms per cubic meter — according to data from the Minnesota PCA. Most MPCA monitors came online in 2000.

“Good” air quality is considered to be 50 or lower. Air is “very unhealthy” at 201 or greater.

MPR News has gathered questions from readers and listeners about the smoky air descending on the state; here are answers to some frequently asked questions.

Why is the air quality so bad? 

Several large wildfires are burning north of the border in Canada, in western Ontario and Manitoba. When the wind comes out of the north, it can funnel smoke from those fires across Minnesota. High pressure is forecast to remain over the state until Tuesday, causing the smoke to recirculate, leading to a prolonged period of smoky, hazy air. 

Wildfire smoke contains fine particles that are really small (less than 2.5 micrometers across). By comparison, a human hair is around 60 micrometers in diameter. Fine particles can lodge in the tissue deep in your lungs, and can make their way into the bloodstream. They can cause shortness of breath, coughing, chest pain and fatigue. 

Smoke from wildfires in Canada caused poor air quality and visibility in the Twin Cities. Credit: Jaida Grey Eagle | Sahan Journal

How long is it supposed to last? 

Smoke will continue pouring into the state into Sunday, and will linger through Monday. Fine particle levels are expected to improve on Tuesday as southerly winds start moving the smoke out of Minnesota. 

Where is the air quality the worst? 

According to an update from the Minnesota Pollution Control Agency on Saturday, fine particle levels are expected to reach the Red (unhealthy for everyone) or Orange (unhealthy for sensitive groups) AQI categories through the weekend.

Purple AQI readings — a level considered very unhealthy for everyone — are still possible, but the MPCA reported Saturday that “some rain fell over the most intense wildfires last night and the smoke is less prolific compared to the past 2-3 days.”

Who’s at highest risk from the bad air? 

Those at highest risk include people with chronic lung diseases or cardiovascular conditions, including asthma, COPD, heart disease and high blood pressure. Children and older adults are also more sensitive to unhealthy air quality, as are people doing extended physical activity outdoors. 

Pregnant women should also be cautious. Smoky air can be harmful to a developing fetus, said Dr. Zulfiqar Ali, a pulmonologist with Sanford Health in Fargo.

What precautions should people with underlying heart and lung conditions take to stay safe? 

Those at the highest risk, including people with chronic lung diseases or cardiovascular conditions, and children with chronic respiratory issues like asthma, should avoid going outdoors as much as possible, said Dr. Justin Stocks, a pulmonary and critical care physician at CentraCare in St. Cloud.

Those people also should keep their rescue inhalers with them, Stocks said.

The MPCA recommends that people with asthma should review and follow the guidance in their written asthma action plan. If you don’t have a plan, make an appointment with your health-care provider. 

The Crow Wing County Courthouse in Brainerd, Minn., is obscured by smoke on Thursday. Credit: Kirsti Marohn | MPR News

Should I go for a walk or run outdoors? 

Generally speaking, it’s not going to be hazardous for healthy people to exercise outdoors for an hour, Stocks said. But, prolonged activity outdoors for multiple days could cause some respiratory symptoms. 

The MPCA offers this advice: Limit, change or postpone your physical activity level as needed. If you experience respiratory symptoms like shortness of breath or coughing or wheezing, then cut back or avoid doing those activities outdoors. 

The MPCA says in areas with very unhealthy air (the purple category), sensitive people should avoid any outdoor activity, and everyone else should avoid prolonged exertion. 

In areas where the air is in the red, or unhealthy category, sensitive individuals should avoid prolonged exertion, and everyone else should limit it. 

Should I keep my kids inside? 

Not necessarily. “If they can tolerate being outdoors for a limited amount of time for an activity, then certainly do it,” said Stocks. But he cautioned that there are many children with undiagnosed asthma, who may experience worsened symptoms in poor air quality. 

Dr. Ali in Fargo takes a more cautious approach. He recommends skipping the soccer practices for a few days until the air quality improves. 

Physical exertion outdoors means you’re not only exposing yourself to air pollution, he said, but because you’re breathing harder, you’re inhaling 1.5 to 2 times as much air. “And in this way, you will breathe more polluted air inside, and that will be more harmful,” Ali said. 

In general, watch your kids for symptoms, and don’t be afraid to modify your behavior over the next few days. It’s not a bad idea to play inside instead of going to the playground, said Jesse Berman, an environmental epidemiologist at the University of Minnesota. 

He also recommends going outdoors in the morning, when the air is cooler and the air quality tends to be a little bit better. 

Should I wear a mask? 

Masks can be helpful for people most at risk from the unhealthy air — people with lung diseases and cardiovascular conditions. But properly fitted N95 masks should be used, said Stocks. Surgical masks only filter out a small percentage of fine particles. 

Does air conditioning help?

Yes. The MPCA advises using indoor air filtration or air conditioning with the fresh-air intake closed/set on recirculate to reduce indoor air pollution.

But if you have to open your windows, try to do it in the morning and at night. Avoid the middle of the afternoon when air quality is going to be at its worst, said Berman. 

How worried should I be about going outside? 

Healthy people shouldn’t be overly concerned about being outdoors for limited amounts of time.

“Don’t panic,” stresses Stocks.

If you have a chronic health problem that could be exacerbated by the air pollution, then minimize your exposure, he said. For those who aren’t in high-risk categories, “it’s a good idea to avoid bad air, but don’t completely change all of your plans,” Stocks said. 

CONTRIBUTING REPORTER Dan Kraker is based in Duluth, Minn., and covers northeastern Minnesota for MPR News.