Poor air quality due to wildfire smoke is a growing public health concern, even if you don’t live in a province with active fires.Illustration by Photo illustration by The Globe and Mail. Sources: iStock
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Poor air quality due to wildfires during the spring and summer months in Canada is becoming more common. In 2023, Canada saw record-breaking wildfires and the 2025 season is already off to an intense start.
This has become not just a seasonal nuisance – it’s also a growing concern for public health. Even if you don’t live in a province with active wildfires, wind patterns can spread smoke thousands of kilometres away from the source – bringing with it immediate and noticeable health impacts.
Wildfire smoke is affecting air quality across the country. Here’s what you need to know
Every year, I see more patients in the emergency department with respiratory issues linked to wildfire smoke and poor air quality, including difficulty breathing, coughing, sore throat, wheezing, asthma attacks and low oxygen levels. And research has found that asthma-related emergency department visits increase during wildfire smoke episodes.
Here are some things to help you understand what poor air quality means for your health – and how to stay safe this wildfire season.
What is the Air Quality Health Index (AQHI)?
Air quality refers to the amount of pollution particles suspended in the air. These particles can come from sources such as vehicle emissions, industrial activity, fossil fuel combustion, and, of course, wildfire smoke.
The Air Quality Health Index (AQHI) measures air pollution and the potential health risks so people can take steps to protect themselves, such as modifying their activity levels. It’s important to familiarize yourself with the index, which ranges from level one to 10+.
Levels one to three indicate a low risk and no precautions are required for the general population when it comes to outdoor activities.
Wildfire threatens Squamish, B.C., as Environment Canada warns of more fires this summer
Levels four to six signal moderate risk, when individuals should consider reducing or rescheduling outdoor activities if they are experiencing symptoms such as coughing or throat irritation, or if they have underlying conditions such as heart or breathing problems. People who fall into that category should stay indoors where possible.
Levels seven to 10+ mean high or very high risk for experiencing the effects of poor air quality. During these times, outdoor activity should be limited or avoided, especially for at-risk populations such as children, the elderly and people with underlying health conditions.
What does poor air quality do to your lungs?
You may think air pollution is just an annoying smell of smoke – something you notice when it’s hazy outside or when your throat feels a bit scratchy – but the effects can cause significant damage to the lungs. Symptoms can be both short-term and long-term.
When air pollution levels rise, you might experience immediate symptoms such as coughing, throat irritation, wheezing, shortness of breath, eye and nose irritation and headaches.
For those with asthma or chronic obstructive pulmonary disease (COPD), even mild air pollution can trigger flare-ups, which is why it’s recommended that those with underlying health conditions avoid time outdoors even when the AQHI is at moderate levels.
Exposure to air pollution over time can change the structure of the lungs, leading to inflammation, scarring and decreased lung function in the following ways:
- Reduced lung function: Breathing polluted air regularly can cause chronic inflammation and damage to lung tissues, leading to progressive breathing difficulties.
- Progressions of asthma and COPD: Repeated exposure also increases the likelihood of irreversible airway remodelling, making asthma and COPD more severe over time.
- Increased risk of lung cancer: Many pollutants in the air, such as benzene and formaldehyde, are carcinogenic. Chronic exposure increases lung cancer risk, even for non-smokers.
Air pollution affects more than just lung health
Air pollution affects every system in the body, and long-term exposure is also associated with reduced life expectancy. In a 2021 report, Health Canada estimated that air pollution contributes to more than 15,000 premature deaths a year in Canada. Air pollution can affect:
- Heart health: Pollution particles can enter the bloodstream through the lungs, leading to inflammation in the arteries and an increased risk of high blood pressure, heart attacks and strokes.
- Brain and cognitive function: Research suggests an association between long-term exposure and increased risk of Parkinson’s disease and Alzheimer’s disease.
- Pregnancy and childhood development: Pregnant individuals exposed to pollution are more likely to experience preterm births and low birth weight while children growing up in polluted environments may develop weaker lung function.
Who’s most at risk?
While poor air quality affects everyone, some groups are at higher risk for complications, including young children, the elderly, pregnant people and individuals with heart disease, lung conditions or diabetes.
These groups should limit outdoor activity at lower AQHI levels than the general population, because even low and moderate air pollution can cause symptoms.
How to protect yourself
While you can’t control pollutants like wildfire smoke, you can take steps to minimize your exposure and symptoms such as:
- Monitor AQHI levels regularly: Environment Canada publishes AQHI forecasts. And BlueSky Canada, a project supported by multiple partners including British Columbia and Alberta, has created a public smoke forecast map.
- Stay indoors when air quality is poor: When AQHI levels rise, limit outdoor exercise and unnecessary exposure. Remember that the AQHI threshold varies depending on your underlying risk profile.
- Use air purifiers indoors: Especially if you or a family member has respiratory issues. Health Canada has a list of specifications you should look for when choosing an air purifier.
- Mask up: Wear a well–fitted N95 respirator mask when spending time outdoors in high AQHI conditions.
- Recognize warning signs: If you notice persistent shortness of breath, chest pain, dizziness or worsening respiratory symptoms, seek medical attention immediately.
Dr. Shazma Mithani is an emergency physician working with adult and pediatric patients in Edmonton. Dr. Mithani is actively involved with the Canadian Medical Association, Alberta Medical Association and Sexual Assault Centre of Edmonton. She is also co-host of The Doc Talk Podcast.
