Toronto’s air quality is among the worst in the world — again — due to wildfire smoke

Toronto had some of the world’s worst air quality on Wednesday, according to global air quality tracker IQAir, as smoke from forest fires over northeastern Ontario and Quebec moved into the city.

Toronto had already placed among the world’s worst for air quality earlier this month, but it eventually fell further down the list.

IQAir ranked Toronto as fourth in the world for poor air quality on Wednesday morning, following Dubai in the No. 1 spot, as well as Detroit and Chicago in the second and third spots, just some of the U.S. cities that are contending with smoke from Canadian wildfires.

Canadian wildfire smoke even crossed the Atlantic, according to Europe’s Copernicus Atmosphere Monitoring Service, with most of the smoke reaching western Europe on Monday and predicted to continue further east until Thursday.

Environment Canada issued a statement saying Toronto’s conditions were expected to improve for some areas on Thursday night.

Wildfire smoke health risks

Even at low concentrations, wildfire smoke can be harmful to health, Environment Canada warns.

While people respond differently to smoke, it adds that those with lung disease (like asthma) or heart disease, older adults, children, pregnant people, and people who work outdoors face greater risks to their health.

The pollutant that carries health hazard concerns in wildfire smoke is known as PM2.5, as measured by Canada’s Air Quality Health Index.

PM2.5 is the by-product of the smoke emitted by wildfires — fine particles of matter with a size of 2.5 microns or less. You could fit about 30 of them across the width of a hair.

At this size, PM2.5 can easily sift down through air passages to the depths of the lungs. At that size, it can also pass into the blood, causing a system-wide inflammation that can exacerbate heart conditions and potentially cause cancers.

Those particles are capable of infiltrating almost every organ in the body, said Matt Adams, director of the Centre for Urban Environments at the University of Toronto.

Air pollution harms cognition and mental health

Scientists warn that even brief exposure to forest fire smoke and air pollution also has the potential to harm brain function.

Sarah Henderson, the scientific director of Environmental Health Services at British Columbia’s Centre for Disease Control, told the Star that studies show wildfire smoke exposure generally lowers brain performance in the short term. People who breathe in more air pollution consistently perform worse on cognitive tests, research shows.

There are fewer studies on the long term impact, but the knowledge around air pollution can be applied to smoke, Dr. Samantha Green, a physician at Toronto’s Unity Health, said.

“We know that particulate matter and other components of air pollution can cause long-term neurological harm,” Green said. “For example, there’s growing evidence associating long-term exposure to air pollution and an increased risk of dementia.

“There is also similarly an increased risk of Parkinson’s disease from long term exposure to air pollution, and increased risk even of ALS,” Green continued.

Different risks — such as “increased prevalence of ADHD, lower IQ scores, increased need for academic support” — are associated with young children, she said.

How to protect yourself from forest fire smoke

Environment Canada advises people to check the Air Quality Health Index and monitor symptoms. People should stop or reduce their activity level if breathing becomes uncomfortable or if they begin to feel unwell, it adds.

If they’re experiencing mild irritation and discomfort, drinking lots of water can help.

Keeping doors and windows shut if the temperature inside a home is comfortable is best, along with avoiding smoking or vaping indoors, burning incense and candles, frying foods, using wood stoves and vacuuming.

Jeff Brook, an associate professor at the University of Toronto’s Dalla Lana School of Public Health and Department of Chemical Engineering and Applied Chemistry, told the Star there are many steps people can take to clean the air inside, such as building an air purifier or using a “state-of-the-art” portable air cleaner or HVAC system.

Other steps people can take include wearing a mask outdoors and keeping children, who are considered by experts as being more susceptible to smoke because their lungs are still developing, indoors on particularly poor air quality days.

Considerations for buying a respirator to combat worsening air quality

Those who have to spend time outside should wear a well-fitted mask, such as a NIOSH certified or N95 equivalent, Environment Canada says.

As air quality worsens due to climate change, some people have pointed to the use of elastomeric respirators as an alternative to regular pandemic-style masks.

Respirators are “gas mask” sized and have “disc shaped attachments” on either side of the face that can be changed to clean the air differently, Brook explained.

“You can have modules that just remove, say, the particles, or modules that remove particles plus some of the gases that can be harmful (and) create odours,” he said.

While needing such masks and respirators is “clearly not the way we want the world to go,” Brook said “they all provide a benefit in terms of protecting you from what you’re breathing in.”

Especially for people who need to be outside for long periods of time, wearing a really well-sealed mask for several hours can be onerous and may be tempting to remove for some time. In this case, Brook said it may be more beneficial to wear a mask with less of a tight fit as long as it’s kept on for the entirety of time spent outside.

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