Global Air Quality Rankings Place Toronto Among the Worst
Toronto Experiences Deteriorated Air Quality Due to Wildfire Smoke
Toronto is currently grappling with poor air quality, with the primary cause being wildfire smoke from hundreds of active fires burning across Canadian provinces, including Ontario. According to reports from NASA, IQAir, and Air Quality Ontario, the smoke has produced large amounts of black carbon particles, a key component of fine particulate matter known as PM2.5, which significantly reduces air quality.
The wildfire smoke plumes, driven by weather patterns, have moved eastward, affecting multiple provinces and parts of the northern U.S. In Toronto, the high concentrations of PM2.5 reached levels triggering Air Quality Health Index (AQHI) warnings of level 10 or above, indicating a very high health risk. On certain peak days, Toronto's air quality ranked among the worst globally, second only to Kinshasa.
The potential long-term effects on Toronto's air quality from persistent wildfire smoke include sustained high levels of fine particulate matter (PM2.5) in the air, which can aggravate cardiovascular and respiratory diseases such as asthma, bronchitis, and other lung conditions. Chronic exposure to black carbon and other pollutants can elevate the risk of chronic respiratory illnesses and cardiovascular problems, especially among vulnerable populations like children, the elderly, and those with pre-existing conditions.
Air quality expert Jed Kaplan warned that fine particulate matter from Canada's forest fires can penetrate deep into the lungs. He emphasized the importance of avoiding prolonged outdoor activities during smoky conditions. If someone must spend time outdoors, wearing a well-fitting respirator-type mask is recommended to reduce exposure to fine particles in the smoke.
If a home does not have an air purifier, Kaplan suggested going to places like libraries or malls that are likely to have clear air. Torontonians can stay updated on the city's air quality health index by visiting airhealth.ca.
The wildfire smoke is anticipated to impact much of southern Ontario throughout the day and potentially into Tuesday. As of 6 a.m. on Monday, the AQHI for downtown Toronto was at a six, which is a moderate risk. It is forecasted that the AQHI will reach a high of seven - a high risk - before tapering off to a five by the evening.
Environment Canada urges limiting the amount of time spent outdoors and considering reducing or rescheduling any outdoor plans due to the smoke levels. They also advise keeping windows and doors closed to prevent wildfire smoke from entering homes.
Common symptoms of poor air quality include eye, nose, and throat irritation, headaches, or a mild cough, while wheezing, chest pains, or a severe cough are potential but less common symptoms. If you experience any of these symptoms, it is advisable to seek medical attention.
Kaplan also advised using air conditioners or air purifiers to improve indoor air quality. He emphasized that air quality and visibility due to wildfire smoke can fluctuate over short distances and can vary considerably from hour to hour.
[1] NASA, IQAir, and Air Quality Ontario sources, August 2025. [2] IQAir, August 2025. [3] Environment Canada, August 2025.
- Toronto's current poor air quality, caused by wildfire smoke, is linked to deteriorating health, as persistent high levels of fine particulate matter (PM2.5) can aggravate cardiovascular and respiratory diseases like asthma and bronchitis.
- Prolonged outdoor activities should be avoided during smoky conditions, as fine particulate matter from Canadian forest fires can penetrate deep into the lungs, potentially increasing the risk of chronic respiratory illnesses and cardiovascular problems among vulnerable populations like children, the elderly, and those with pre-existing conditions.
- Environmental science and climate change play a role in air quality, as increased wildfire activity, possibly linked to a changing climate, can contribute to higher concentrations of pollutants, thereby affecting health in cities like Toronto, and requiring the implementation of strategies like air quality monitoring systems, public health advisories, and indoor air improvement measures like air purifiers or wearable masks.
