In an effort to determine the levels of air pollutants during the coldest months of the year, Environment and Climate Change Canada is leading a study in partnership with York University’s Air Pollution Lab. The Study of Winter Air Pollution in Toronto (SWAPIT) involves more than 90 scientific and technical experts conducting around 44 projects, making this the largest study of its kind globally.
Few studies have explored air quality during the coldest months. This gap in research is especially significant during extreme weather events that increasingly occur due to climate change.
SWAPIT is led by Elisabeth Galarneau, air quality research scientist at ECCC. “Studies like this can lead to improved tools for testing air quality and provide better information about our urban cities across the country,” says Galarneau.
The results could offer new insights into how pollutants behave in colder months and what factors contribute to air quality deterioration. There are different sources of pollutants from indoor heating to the de-icing of highways, which could have impacts.
“There is a need to understand what pollutants are most prevalent in the air in the winter as different sources of contaminants become more prevalent during that time compared to the summer, things like high particulate matter from forest fires which is unlikely during winter,” says Professor Cora Young of York University.
It’s been proven that the levels of some pollutants are elevated in the winter months. The study also seeks to uncover how different contaminants interact to form new compounds, potentially posing additional health risks. York University researchers deploy a spectrometer, a particulate matter sensor, and an anemometer to measure wind speed and direction. These tools, along with cameras monitoring traffic patterns, provide valuable insights into pollution sources and distribution. Among the pollutants being measured are per- and polyfluorinated substances (PFAS), volatile organic compounds (VOCs) like benzene, and trace contaminants such as flame retardants and plasticizers. The study aims to understand how these pollutants vary across the city and over time.
The initiative brings together public organizations, environmental scientists, and air quality specialists to analyze data from a vast network of monitoring sites. These include long-term air monitoring stations as well as temporary locations added specifically for SWAPIT. Air quality measurements are being taken at:
- High Park in Toronto’s west end
- Evergreen Brick Works near the Don Valley Parkway
- University of Toronto’s Scarborough and St. George campuses
- York University’s Keele campus
- The CN Tower
- Roadside poles across the city
- Mobile monitoring vehicles driving through various neighborhoods
- Toronto Pearson International Airport
By studying air quality at these diverse locations, researchers are mapping how pollution varies across the city and identifying which sources contribute the most to winter air pollution.
A key question SWAPIT seeks to answer is why certain air pollutants have not declined as expected in recent years. The study will help determine what sources and processes contribute to Toronto’s urban air pollutant mixture, how these pollutants vary by location and time, and how they relate to public health risks.
SWAPIT’s findings will play a critical role in identifying pollution trends and developing strategies to reduce harmful emissions. As data collection wraps up and analysis begins, researchers are eager to share their insights with policymakers and the public. The study’s results will contribute to evidence-based solutions that help create cleaner, healthier urban environments for all Canadians.
Ultimately, the goal of SWAPIT is to identify the sources of pollution affecting air quality in different seasons and inform policies that can mitigate their impact.
