Air pollution eases in 4 Canadian cities as pandemic measures keep people home

Public health measures shutting downworkplaces and schools to fight theCOVID-19 pandemic have led to a noticeable reduction in air pollution in multiple Canadian cities known for their traffic congestion, according to satellite images shared with CBC News.

Toronto, Edmonton, Calgaryand Vancouver have seen drops in vehicle traffic over the last few days as physical distancing measures introduced toslow the spread of the novel coronavirushave kept Canadians closer to home.

Images from Descartes Labs of the major cities and surrounding areasshow their average levels of atmosphericnitrogen dioxide (NO2) a pollutant created by the burning of fossil fuels, such as gasoline hasplummeted compared to a year ago. The New Mexico-based geospatial analysis group shared the data with some news organizations, including CBC and the New York Times.

The composite images come from the European Space Agency's Sentinel 5P satellite and show averages over time.

"It seems pretty clear to us that things are slowing down in cities because of the outbreak," Tim Wallace, the head of creative atDescartes Labs, toldCBCNews.

MostNO2emissions come from vehicles. The gas has a pungentodourand in high concentrationsit can irritate the lungs and cause coughing, wheezing and difficulty breathing. Prolonged exposure has beenlinked to the development of asthma and other illnesses, according to the U.S. Environment Protection Agency.

Toronto

According to the traffic analysis firm Inrix, Toronto was the most congested city in Canada in 2019 and the 19thmost congested in the world. Ontario's residentswere asked by their provincial and federal governments to stay home in March the clear reduction in NO2 levels since then shows that they've been listening.Other cities, includingOshawa, Brampton and Hamilton, have also seendeclines. (You can movethe slider on the images below to see the year over year differences.)

Edmonton and Calgary

Edmonton and Calgary both saw similar emission declines within their urban cores and along Hwy 2, the main artery that connects the two cities.

Vancouver

British Columbia has been outpacing the rest of Canada in the adoption of electric vehicles and the province is considered by some to have a robust"green culture." But even those on the West Coast might be breathing a bit easier lately as the city and its surrounding areas seeless traffic.

Impact on greenhouse gas emissions?

Nitrogen dioxide should not be confused with greenhouse gases butbecause it and carbon dioxide are both produced when fossil fuels are burned, there is a relationship between levels of NO2 and carbon dioxide emissions the gas most associated with climate change.

"These are striking reminders of the impacts of the way that we are living now and our striking use of fossil fuels," said Michael Brauer, a professor in the School of Population and Public Health at the University of British Columbia.

Ryan Katz-Rosene,president of the Environmental Studies Association of Canada, said that the world should seea decline in greenhouse gas emissions as result of this pandemic.

And while the immediate concern should be the health and well-being of citizens, Katz-Rosene, an assistant professor of political studies at theUniversity of Ottawa,said policymakers should use this time toconsider how post-pandemic stimulus and recovery money could be directed atcreating jobs in clean tech, encouraging companies to use lesscarbon-intensive technology and building greener transportation networks.

"(We need to make) sure that we use the post-pandemic stimulus packages to work towarda just transition," hesaid.