Urban air pollution is made up of a complex mix of hundreds of substances including toxic air pollutants and criteria air contaminants such as nitrogen oxides (NOx), sulphur oxides (SOx), ozone (O3) and particulate matter (PM). Air pollution can cause heart and breathing problems, affect birth outcomes, brain development and function, and is linked to cancer, chronic diseases (including diabetes), and other illnesses. Air pollution can affect people differently, and some people are more vulnerable to the health effects from air pollution. Reducing air pollution can result in better health outcomes for everyone.

The sources of Toronto’s air pollution

The air pollutants found in Toronto are mainly the by-products of burning fossil fuels. When we burn gasoline, diesel fuel, natural gas and coal in our cars, trucks, home furnaces, industries and power plants, we send pollutants into the air. Traffic-related air pollution (TRAP) is the largest local source of air pollution in Toronto, followed by emissions from industrial and residential sources. Toronto’s air pollution comes from local sources in Toronto and from beyond, and air pollution from Toronto can affect other communities.

About smog

In the past, smog and smog advisories were common for Toronto. Smog is a mixture of pollutants in the air that can affect our health and the environment. It sometimes appears as a brownish haze. Smog is made up of ground-level ozone, fine particles and other pollutants. Smog can occur any time of year, but it is most common in the summer. Smog can affect outlying suburbs and rural areas as well as big cities.

Thankfully, Toronto has not experienced a smog advisory since 2016. However, the persistence of air pollution means that smog remains a possibility in Toronto.

The TPH report Path to Healthier Air: Toronto Air Pollution Burden of Illness Update identified that Toronto is on a path to healthier air, but that more work needs to be done to ensure ongoing improvement in the City’s air quality.

The report found that:

  • Over half of Toronto’s air pollution is from sources within the City’s boundaries
  • Exhaust emissions from cars, trucks and other on-road vehicles are the largest source of local air pollution in Toronto
  • Air pollution continues to contribute to hospitalizations and premature deaths in Toronto
  • Reducing emissions from traffic and industrial sources, and reducing our use of natural gas are actions that can give the greatest benefit to improving Toronto’s air quality

Read the report to learn more about the health impacts from air pollution in Toronto.

Toronto Public Health works collaboratively with other City divisions in addressing air quality issues like wildfire smoke in order to protect the health of people in Toronto.

Find out more about some of these initiatives below.

TransformTO Net Zero Strategy

The TransformTO Net Zero Strategy aims to reduce community-wide greenhouse gas (GHG) emissions to net zero by 2040. The City’s 2040 net zero target is one of the most ambitious in North America.

Learn more about the TransformTO Net Zero Strategy.

Avoiding the TRAP

Traffic related air pollution (TRAP) is the largest local source of air pollution in Toronto. The TPH report Avoiding the TRAP: Traffic Related Air Pollution in Toronto and Options for Reducing Exposure identifies a number of strategies that can effectively mitigate exposure to traffic pollutants for people in Toronto.

Read the report to learn more about reducing traffic related air pollution in Toronto.

Idle-free Toronto

Idling gets us nowhere. Exhaust emissions from cars, trucks and other vehicles are a major source of air pollution in Toronto. Running your engine while parked for more than 60 seconds is prohibited under City of Toronto By Law 517.

Learn more about the health and environmental impacts of idling, and about the City’s Idling Control By-law.

Most heating, ventilation and air conditioning (HVAC) systems draw fresh air from outdoors. So, it may not be possible to completely prevent outdoor air and air pollution from entering your home. Still, there are actions that people can take to reduce the amount of outdoor air pollutants entering their home:

  • Close windows and doors if the temperature is comfortable indoors or use air conditioning to cool your home if available
  • Use the highest efficiency filter that is approved for your HVAC system – refer to the manufacturer’s and/or installer’s instructions
  • If possible, set your HVAC system to recirculate to prevent it from drawing in outside air until conditions improve
  • Limit the use of exhaust fans when cooking or showering as these may draw in outside air

Other measures to keep indoor air clean:

  • Don’t smoke or vape indoors when trying to keep your indoor air clean
  • Reduce indoor sources of particulate matter – refrain from lighting candles and incense, frying foods, using a gas stove and vacuuming
  • If you do not have a HVAC system with a filter, a portable air cleaner with a HEPA filter can clean the air in one area of your home; you can also make a portable air filter yourself using a box fan, air filters and other easily purchased .

If unable to get relief from air pollution including wildfire smoke at home, people can go to a public facility with air conditioning like a library, recreation centre or shopping mall.

People are encouraged to visit the AQHI health guide to evaluate their sensitivity to air pollution. Learn more about the AQHI below.

Everyone can take meaningful steps to reduce their own contributions to air pollution:

  • Take public transit, carpool, walk or bike instead of driving
  • Reduce or eliminate wood-burning in fireplaces, woodstoves and others
  • Use less energy (gas, oil and electricity) for home heating, and conserve electricity at home
  • Choose energy-efficient appliances, and choose renewable energy sources where possible

Learn more about what you can do to reduce emissions.

The Government of Canada and the Ontario Ministry of the Environment, Conservation and Parks (MECP) will jointly release air quality alerts like a Special Air Quality Statement (SAQS) or a Smog Air Health Advisory (SAHA) when the Air Quality Health Index (AQHI) is forecast to be high. People can sign up to receive air quality alert email notifications on the MECP webpage.

Visit the Ministry of the Environment, Conservation and Parks webpage to learn more about SAQS and SAHA. See below to learn about the Air Quality Health Index (AQHI).