What to know
- Toronto had the worst air quality of any major city in the world on Wednesday as wildfire smoke from northeastern Ontario pushed the Air Quality Health Index to a rare maximum reading of 10+.
- Experts say fine particulate matter (PM2.5) in wildfire smoke poses serious health risks because it can enter the lungs and bloodstream, worsening respiratory and heart conditions.
- Although climate change is making wildfire smoke events more frequent, experts say Canada’s overall air quality has improved over the past three decades due to lower pollution levels.
- Residents are urged to stay indoors when possible, keep windows closed, and wear a well-fitted N95 or KN95 mask outside, while experts say governments should expand wildfire prevention efforts such as prescribed burns.
Toronto’s air quality on Wednesday was poor enough to make it the major city with the unhealthiest atmosphere in the world. With wildfires happening more year after year, some experts are saying the air has actually gotten cleaner over the years.
What happened on Wednesday?
Heavy wildfire smoke blanketed the city on Wednesday morning, persisting through the day due to multiple wildfires in northeastern Ontario.
This smoke coming down from around the Thunder Bay area led the city to have strong pollutants in the air, making it dangerous for residents to be outdoors for long periods of time.
Toronto broke Environment Canada’s Air Quality Health Index, reaching the top number around late morning on Wednesday.
“Toronto is mostly low risk,” said Rebecca Saari, University of Waterloo associate professor of civil and environmental engineering and a Canada Research Chair in Global Change, Atmosphere, and Health. “Its average air quality is between a level of two and three… Right now we’re at 10 plus.”
Saari added that a rank of “10+” is incredibly rare.
The rating came with an orange warning from the federal government, cautioning all residents to stay indoors if possible, regardless of whether they are part of a vulnerable group (elderly, child, pregnant, or with underlying health conditions) or not. Everyone is at risk.
What makes the air quality dangerous?
“The peaks that we’re seeing, the really extreme levels that we’re seeing, are in this particulate matter, and we know that particulate matter is a major health concern,” Saari said. “…These are small particles that can get past your airways into your lungs, and even into your bloodstream.”
Particulate matter, also known as PM2.5, can be microscopic. So much so, it can bypass typical blue medical masks and even the body’s natural defense systems. Outcomes, at times, can be deadly.
“Particulate matter is associated with around 17,000 deaths every year in Canada and about $140 billion in economic damages,” Saari said.
“…We’ve seen particulate matter start to go up and up and up, and for these very high-risk days like today.”
Particulate matter can be made up of smoke, soot, liquid, mould, bacteria, pollen and/or animal dander, according to Health Canada.
Inhaling this matter can cause decrased lung function, and can alsio aggrevate underling conditions, such as asthma, COPD and heart disease.
Common symptoms include eye, nose, and throat irritation, headaches, and a mild cough. More serious, though less common, symptoms can include wheezing, chest pain, and a severe cough.
People who work outdoors are encouraged to reduce or avoid strenuous outdoor activity where possible and seek medical attention if they experience concerning symptoms.
Residents are also advised to keep windows and doors closed to limit smoke from entering their homes.
Have we been seeing more wildfires yearly?
According to Saari, Canada has been seeing more wildfires year after year, greatly affecting the environment and residents nearby.
“Climate change has already increased the risk of wildfire in Canada,” she said. “It does seem that we have some evidence that it’s becoming more likely that we would have more wildfire-driven alerts in the summers.”
University of Toronto Professor of Chemical Engineering and Applied Chemistry Arthur Chan studies indoor and outdoor air pollution. He says the wildfires and days of poor quality have definitely become more frequent.
“I grew up in Toronto, and I don’t remember any of this when I was growing up. Historically, we haven’t had these really bad wildfire episodes,” he said.
He added that dry conditions can contribute to this, with fuel-like environments, such as grass and trees, strengthening the flames, and mostly due to high heat and climate change.
“The average temperatures are getting warmer, and the precipitation patterns are changing. The fuels are getting drier, and as a result, they can burn more easily,” he said.
Saari also added that the heat is a contributing factor as well.
“Hot, stagnant weather can allow smog to build up more intensely because pollution can’t get away.”
Is the air quality of the city getting worse?
With frequent wildfires annually, it seems like Canadians are being told to avoid breathing in smoke more often.
Although Saari added that’s not necessarily the case.
“Canada is still very, very clean. These are still rare events,” she said. “Canadian air quality is generally very good… since we started really measuring in about 1995…we’ve seen averages go from more in the moderate to low-risk category.”
Saari added that over the past 30 years, the data shows a small positive increasing trend in those very high-risk days
Data from the Ontario Government shows a decrease of both PM2.5 concentrations (12 per cent) and PM2.5 emissions (23 per cent) year after year since 2014.
“We have made strides in reducing harmful emissions of several pollutants over the past decade as well,” Saari noted.
The Canadian government has a 2030 Emissions Reduction Plan, which targets decarbonizing blue-collar industries, switching to electric vehicles, and embracing nature. The ultimate goal of the plan is to reduce carbon emissions to 40 per cent, getting it below 2005 levels by 2030 and net-zero emissions by 2050.
“We do generally see things are improving… but we also see a small increasing trend in these very high-risk days,” Saari noted.
What else can the government do?
Chan said there has been some conversation about Canada using “prescribed burns.”
“If there’s a lot of growth, it accumulates a lot of fuel… it becomes a stronger wildfire, and it can spread over larger areas,” he explained. “So, one of the management strategies is to clear that up, before that growth accumulates, you would do a burn, keep the burn small, and you could clear up the forest once in a while.”
He also added that prescribed burns tend to be a common practice in the U.S.
Chan also suggested the government figure out a predictive symptom so they can tackle a wildfire before it becomes out of control.
“If we could predict them better and know more about how they spread, I think that would help.”
How residents can stay safe
Chan said the best way to protect yourself, other than staying indoors, is by wearing the right mask.
“If they really want to protect themselves from wildfire smoke, getting an N95 or a KN95, well-fitted mask, is going to be very effective,” he advised. “The cloth masks might work for and for COVID, but they don’t work as well for wildfire smoke.”
This is due to the size of the particulate matter, as their microscopic size can pass through filters that aren’t strong enough to block them out.
Chan said it’s important to protect yourself, as there are still many things up in the air when it comes to the details of how wildfire smoke can affect a person.
“We need to learn more about how wildfire smoke impacts human health…” Chan said.
“Whether this particulate matter might have different health impacts from other types of pollution from urban sources is still a big unknown.”
