Air Pollution and Health
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), and particulate matter (PM).
What is smog?
Sometimes people talk about “smog”, a mixture of pollutants in the air that can affect our health. Smog can occur any time of year, but it is most common in the summer. It sometimes appears as a brownish haze. Smog is made up of ground-level ozone, fine particles and other pollutants. Smog can affect outlying suburbs and rural areas as well as big cities.
Where does smog come from?
The air pollutants that make up smog mainly come from burning fossil fuels. Every day we burn gasoline, diesel fuel, natural gas and coal in our cars, trucks, home furnaces, industries and power plants, we are sending pollutants into the air. Ozone, the main ingredient in smog, is formed when two pollutants (nitrogen oxides and volatile organic compounds) combine in the presence of sun light. Toronto’s smog comes from sources in Toronto and beyond.
The City of Toronto has a comprehensive smog action plan. The Corporate Smog Response Plan involves City Agencies, Boards, Commissions and Divisions developing smog response plans specific to their functions.
Toronto Public Health works collaboratively with other City divisions in addressing air quality issues such as smog and its effects on health. Find out more about these initiatives.
Special Air Quality Statements and Smog and Air Health Advisories are issued to
- alert people with breathing difficulties to avoid unnecessary exposure to smog
- solicit help from everyone, including industries and major organizations, in reducing emissions
The Ministry of Environment and Climate Change, together with Environment and Climate Change Canada, will issue a Special Air Quality Statement if a high Air Quality Health Index value (7 or greater) is forecast to last for 1 to 2 hours.
The Ministry of Environment and Climate Change, together with Environment and Climate Change Canada, will issue a Smog and Air Health Advisory if a high Air Quality Health Index value (7 or greater) is forecast to last for 3 hours or more.
Idling gets us nowhere. Running your engine while parked for more than 60 seconds is prohibited under City of Toronto By Law 517. Read more about the health and environmental impacts of idling.