air quality toronto

New study shows air quality in Toronto has improved dramatically in recent weeks

The impacts the current pandemic is having on Toronto are huge, and one might be that air quality in the city has actually improved since the lockdown started.

University of Toronto Engineering Professor Greg Evans, together with his team at Southern Ontario Centre for Atmospheric Aerosol Research , have been monitoring the concentrations of a wide range of air pollutants in downtown Toronto for over a decade.

"Our preliminary data indicates that air quality has improved dramatically in Toronto since the pandemic shutdown started," said Evans.

"For example, the concentrations of two traffic-related air pollutants, nitrogen oxides and ultrafine particles, have decreased in downtown Toronto to almost half their concentrations prior to the shutdown."

Data taken from the 2003 SARS-CoV-1 virus (SARS) outbreak suggests that wind increased the virus' propagation while high air pollution doubled mortality in certain places.

An early study from Harvard shows what many already suspect: that death from COVID-19 was substantially higher in counties that have had poorer air quality over the previous 16 years.

"Emissions have decreased in an unprecedented way across Canada and the U.S., which has provided an opportunity to better understand the many sources of air pollution and how these sources influence air quality," said Evans.

"Fortunately, Canada in general has very good air quality, which may work to our advantage during this pandemic. The reduction in emissions due to the shutdown will further improve this advantage."

"While it’s much too early to know if this improvement in air quality is helping to reduce hospitalization, people may still want to err on the side of caution and do what they can to further reduce emissions and their own exposure. This might include limiting their use of gas-powered cars, BBQs, leaf blowers and lawn mowers," he said.

Evans said his hope is that when the economy ramps up again in about a year, "our country will also work with and follow the guidance of Canada’s experts in climate change and sustainability."

Lead photo by

Kevin McBride


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