Staying close to home: Impact of public health measures on air pollution

For those living in large urban centres, sitting in bumper-to-bumper traffic used to be part of the daily grind. But since the COVID-19 pandemic forced many people to telework, traffic patterns have changed drastically. Has this had an impact on the air quality and air pollution in our cities? Scientists Keith Van Ryswyk and Eric Lavigne from Health Canada set out to find out!

As sometimes occurs in science, this study happened almost by accident. In fact, in June 2019, Keith and Eric had undertaken the yearlong Quebec City Air Pollution Exposure and Epidemiology study with colleagues from the Institut national de la santé publique du Québec to examine the sources, trends and levels of air pollution in Quebec City. However, in March 2020, public health measures used to combat the spread of COVID-19 resulted in a decrease in the city's commercial, industrial, traffic and transportation activities.

The researchers were excited to take advantage of this unique opportunity to examine the relationship between human activity and urban air pollution. In fact, they had measured several air pollutants and urban heat data for 13 months, the last four of which the population was under public health measures.

"The estimated impact of public health measures on ambient air pollution is a valuable research question in itself," explains Keith Van Ryswyk. "The public health measures being enforced to combat the spread of COVID-19 presented a unique natural experiment. The reduction of activity of this scale in a city provided a unique opportunity to demonstrate the relationship between human activities and air pollution."

In order to make sure they have the right information to draw conclusions, the researchers will examine information on the population's mobility. The anonymized, permissions-based data is compiled from location-enabled vehicles and devices. It will give the researchers a clear picture of the movements of the population while public health measures were in place and provide a good basis for their analysis.

Once they know more about the movements of the population, they will be able to determine the impact of the COVID-19 public health measures on ambient air pollution over time. "We will be able to determine air pollution levels, which will be adjusted based on weather, background air pollution and time of year," says Eric Lavigne.

The scientists are now hard at work examining the data and determining the true impact of the public health measures resulting from the COVID-19 pandemic on air pollution in Quebec City. Stay tuned to find out the results of this serendipitous study.

Find out more:
Outdoor air pollution and health: Overview