TORONTO -- One major Canadian city recorded carbon monoxide concentrations in its air of 50 per cent less than expected levels during the early days of the COVID-19 pandemic, according to a new study, as lockdown-like measures had most Canadians spending more time at home and less time driving.
The study out of Concordia University in Montreal, which will be published in an upcoming edition of Science of the Total Environment, shows that Canada was not immune to a global trend of declining greenhouse gas emissions during 2020.
Early estimates suggest that emissions of carbon dioxide – the greenhouse gas that is the biggest driver of global warming – fell by seven per cent worldwide last year. Overall greenhouse gas emissions dropped by more than 10 per cent in the United States, marking the largest decrease there since the Second World War. In Germany, the decrease was enough to push the country past its emissions-reduction target for the year.
No official Canadian figures have been published yet, but the Concordia study shows that the amount of key air pollutants was far lower in several large Canadian cities in August 2020 than it was at the same time in recent years.
The Concordia team based their findings on air quality readings from monitoring stations in Vancouver, Edmonton, Saskatoon, Winnipeg, Toronto, Montreal, Halifax and St. John's, as well as published data around traffic congestion and fuel consumption.
They found that emission levels decreased significantly during the pandemic, with the steepest fall occurring during the week in mid-March when most provinces instituted sweeping public health restrictions and the Canada-U.S. land border was closed to most non-essential northbound travel.
The reasons for this are straightforward. The lockdowns and similar measures meant more people were staying at home instead of getting in their cars. Xuelin Tian, the study's lead author, said in a press release that traffic congestion during that first week was 75 per cent lower in Montreal and 69 per cent lower in Toronto than it was during the comparable week of 2019. With fewer vehicles on the road, carbon dioxide emissions were reduced and the air was cleaner.
The reductions were not uniform across the eight studied cities. Only the four largest cities – Vancouver, Edmonton, Toronto and Montreal – were found to have significantly less nitrogen dioxide in their air last August than in previous Augusts. Edmonton also recorded the biggest decrease in carbon monoxide concentration levels, from 0.14 parts per million (ppm) in March 2018 to 0.07 ppm in March 2020.
These decreases will not have a significant effect on the battle against climate change. Some greenhouse gases, including carbon dioxide, can last in the atmosphere for a century or longer, making a one-year blip virtually meaningless over the long term. In fact, greenhouse gas levels in the atmosphere hit another record high in 2020, according to the World Meteorological Organization.
Tian and the other Concordia researchers say their findings show the effect emissions from vehicles have on Canada's air quality, and can also help project what replacing gas-burning vehicles with electric vehicles will do to improve our air.
