Toronto air quality | WWF

Toronto air quality

Posted on
01 March 2012

Researching health effects from air pollution

Toronto is a pioneer in research on the health effects of air pollution. Toronto Public Health has published a dozen reports in the past ten years that quantitatively document the link between poor air quality and illness. These reports have built up support for major remedial measures. And in recent years, Toronto has copied the same approach with climate change.

Keywords: Air pollution, health, research, climate change, coal plants

When Toronto Public Health (TPH) issued their first report in 2000, Air Pollution Burden of Illness, local scientific studies of air pollution’s effects on health were not very common. Since that time TPH has continued its research with the explicit purpose of documenting the health effects of poor air quality and climate change. This also builds political support for action both within the public sphere and in collaboration with private operators – citizens, businesses, and NGOs alike. TPH's strategy has been successful. Toronto currently has ambitious plans for reducing greenhouse gas emissions and improving the quality of the air (see also Toronto, Vitoria-Gasteiz and Dehli). In addition to this, Toronto has become a city that is very active in a broad spectrum of sustainability issues.

Examining health effects
The first report quantified the relationship between air pollution and health by focusing on the number of premature deaths and hospital admissions. In 2004, TPH followed this up with the first comprehensive study of both acute and chronic health effects of particles, and the most important secondary air pollutants. It showed that Toronto’s air pollution annually caused 1,700 premature deaths and 6,000 hospitalisations, as well as 6,000 emergency room visits, 12,000 cases of bronchitis in children and 72,000 days of asthma symptoms. The report attracted a great deal of attention.

In collaboration with the Government of Canada in 2005, TPH copied the same approach with climate change. It examined the total health effects of air pollution and extreme weather conditions using data on air pollution, weather, and deaths between 1954 and 2000. The trends were extrapolated into the future and showed that, with the hot summers expected due to climate change, heat-related deaths will double by 2050 and triple by 2080, while deaths due to air pollution will increase 20 percent by 2050 and 25 percent by 2080 if no preventative action is taken.

Coal plants, traffic and industry
In a report of the same year, TPH showed that coal plants, both in Ontario and in the American Midwest, were significant contributors to Toronto's air pollution. This information was then used in several contexts, including US lawsuits against the coal industry, in which Toronto participated, resulting in a large number of coal plants having to clean up their emissions in the US as well as in Canada. This also resulted in some coal plant closures in Canada. Ontario is now phasing out its coal plants by 2014.

In 2007, TPH investigated traffic's contribution to air pollution in Toronto. The report showed that 440 of the 1,700 deaths caused annually by air pollution were due to vehicular traffic. This “price” of vehicular traffic in terms of health and money was subsequently used as a point of argumentation for an investment in public transport.

The following year TPH commenced a large ongoing study about small- and medium-sized sources of air pollution from local businesses. From 2011, and backed by a new local ordinance, 5,000 companies were forced to track and report 25 substances each year, information that is then made public. The program is the first of its kind in Canada.

Heat waves and air quality index
Toronto Public Health is currently carrying out a study on adaptation to heat waves brought on by climate change; this is to provide support for long-term planning. In addition, TPH is developing, in collaboration with Toronto's Environment Office, a high-resolution model for urban air quality at the neighbourhood level. The model will predict average concentrations of 30 different substances, and the local sources of these. This could support changes in legislation.

TPH is also implementing a study of how income inequality impacts the urban environment, air pollution, and differences in health conditions. Finally, TPH has assisted the Canadian Government in formulating an air quality index, ranging from 0 to 10, which is now used in the city. In addition to being a health risk indicator, the index facilitates the planning of outdoor activities when health threat levels are low.

New York City Global Partners, Innovation Exchange, “Best Practice: Demonstrating Air Quality and Climate Change Impacts on Public Health”, 2011,

“Impact of Traffic Air Pollution on Health in Toronto”, Pollutionfree Cites, September 22 2010, Worldpress,

City of Toronto, Air quality and climate change,

Environment Canada, Air Quality Health Index,

Key data are retrieved from the UN World Urbanization Prospects: The 2011 Revision,

Text by: Martin Jacobson