Mapping smoke from Canada: As wildfires burn, check the air quality in your area

Montana, North Dakota, South Dakota, Minnesota, parts of Wisconsin and Iowa were under an air quality alert Monday because of wildfire smoke coming from Canada.

Canada is fighting 138 active wildfires with dozens that are characterized as “out of control,” according to the Canadian Interagency Forest Fire Centre. The wildfires spread over the past week. Most of the fires are in British Columbia and Alberta. The fires are affecting the air quality of Kansas, Missouri and Iowa.

The smoke can be dangerous because it contains a mixture of hazardous gases and solid particles smaller than a human hair. According to the Environmental Protection Agency, particulate matter, also known as PM 2.5, is a main component of wildfire smoke and is the air pollutant of greatest concern to public health. The fine particles can be inhaled and enter the lungs and bloodstream, where they can damage other organs. 

Intense heat from the wildfires pushes the smoke high into the atmosphere, where it stays until it cools and descends. Sometimes the smoke sinks to the ground. Strong winds can carry the smoke long distances, even thousands of miles. Smoke concentrations during a wildfire rapidly change, which makes it important to frequently monitor updates to smoke predictions. 

Where is the wildfire smoke coming from?

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As these tiny particles make it to ground level, they can also enter indoor spaces. There is good news, however: As smoke moves downwind, it generally becomes more diluted and widespread and less dangerous, according to Susan Stone, a senior environmental health scientist at the EPA’s Office of Air Quality Planning & Standards. That means more people may be affected over a larger area but by less intense air pollution.

Even when smoke is visible in the atmosphere, the actual air quality reading might be lower than expected if the smoke is not concentrated near the ground. 

The EPA monitors air quality near ground level where people breathe and describes the health effects you may experience within a few hours or days after breathing polluted air. The map below shows the level of PM 2.5.

U.S. air quality map

"Predicting if the air quality will improve or worsen can be difficult because of the unpredictable behavior of wildfires and factors such as wind, weather, and terrain," according to an EPA course on air quality for health care providers.

Wildfires burning in the USA and Canada

Depending on what's burning – grasslands, trees, vegetation or buildings – wildfire smoke can contain toxic chemicals such as carbon monoxide, carbon dioxide, acid gases, sulfur dioxide, nitrogen oxides, benzene, toluene, styrene, metals and dioxins, says the New York State Department of Health. 

How toxic wildfire smoke affects your health 

Breathing the toxic smoke can cause a series of problems, from minor irritations to serious concerns, including cardiovascular- and respiratory-related problems. According to Yale Medicine, the PM 2.5 particles are so small they can pass the usual defense mechanisms of the upper airway and penetrate deep into the lungs where they can impair function. The particles can also pass into the bloodstream and travel to other organs. Exposure has been linked to an increased risk of heart attack, stroke, lung cancer and a decline in cognitive function.

Learn more: How bad is breathing in wildfire smoke? Graphics show how toxic air affects your health

Six tips to reduce exposure to wildfire smoke and protect yourself from smoke particles

More coverage about wildfires and smoke:

How bad is breathing in wildfire smoke? Graphics show what toxic smoke does to your lungs

Where will the West's next deadly wildfire strike? The risks are everywhere - search your area

US wildfire, smoke map: Track latest wildfires, red flag warnings across the US

Canadian wildfires have started. Will smoke descend on the USA like last year?

Smoke from Canadian wildfires brings poor air quality to Minnesota Monday, alert issued

Canadian wildfires are leading to air quality alerts in Wisconsin. What that means for you.

Contributing: Janet Loehrke and George Petras