University of British Columbia: COVID-19 lockdowns only reduced air pollution in some parts of the world

When COVID-19 lockdown measures were first introduced last year, schools and shops closed, tourist spots were deserted due to international travel restrictions, and economies slowed down as most people adjusted to life in the confines of their home.

Globally, these measures reduced air pollution by 45 per cent domestically and 35 per cent internationally on average during the first wave of lockdowns. These are the findings of a recent study assessing the global environmental impacts of the initial COVID-19 lockdowns.

But the decrease in air pollution was not the case across the board. Some world regions including parts of South America, Asia and the American Midwest saw an uptick in air pollution based on their economic activity.

“It’s a piece that shows us how complicated the economic activity and the environment relationship is,” says UBC faculty of land and food systems assistant professor Dr. Frederik Noack. “It’s really dependent on the development level and composition of the economy.”

The study shows that a lockdown can, for example, reduce air pollution from traffic and industry but at the same time increase pollution from residential sources such as heating.

Dr. Noack, also a Canada Research Chair in Environmental Economics, says these findings suggest that policies to curb air pollution should take all economic sectors and the response of people to these policies into account including a shift to more polluting activities. He adds that that targeted policies could reduce air pollution while minimizing economic losses.

The study also shows how industry-heavy countries like Canada, which saw a 30 per cent decrease in air pollution between March to August 2020, could learn some environmental lessons from last year’s slowdown in mobility and industry.

Some countries with increases of up to 25%
This study linked detailed data on lockdown timelines with satellite pollution (PM2.5) data from 162 countries, factoring in times where lockdown restrictions eased. The analysis spanned November 2019 to August 2020 capturing medium-run environmental impacts, since most lockdowns were imposed in March or April.



Most changes in air pollution started to be seen after a lag of about one to two months after lockdown measures were set in place. The biggest reductions in air pollution were seen 90 to 120 days into lockdown.

Although the study focused on global urban centres, they found significant differences in air pollution trends from country to country.

Some countries even saw an increase in air pollution of up to 25 percent.



Most of North and South America, Europe, southern Africa, eastern Asia and the Pacific saw improved air quality (purple) during lockdown, but some parts of South America and Asia (orange) saw air quality worsen.

“It’s really about the source of the pollution here,” says Dr. Noack.

“Lockdowns don’t automatically mean air quality improves, because in less industrialized countries you might see more biomass burnings, increased agricultural activities and residential energy use.”

“Building back better” after the pandemic
The results of the study also shed light on how to build more sustainable economies where pollution can be curbed in less economically costly ways other than a full economic shut-down.

Air quality improved in most countries which saw a significant loss in GDP due to lockdowns. But this isn’t true for every country, as some saw an increase or no change in air pollution as a result of lockdown measures.

“There needs to be more nuance when it comes to addressing environmental issues,” says Dr. Noack.

“If we were to save the environment by only focusing on one sector [like limiting manufacturing, industry and transportation], it might give advantage to pollution in a different sector like agriculture.”

He suggests that more industrialized countries like Canada could learn from the pandemic by increasing flexibility for working from home after the pandemic, to reduce the impacts industry and transportation has on their air pollution.

The study also encourages the use of a mix of targeted policies that include all economic activities, and underlines the importance of market-based environmental instruments like pollution taxes or cap and trade systems.

This study was a collaboration between researchers from UBC’s faculty of land and food systems, University of Lausanne, University of Zurich, University of Manchester, University of Bologna, the Enterprise for Society (E4S) Center, and London School of Economics and Political Science.

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