Pandemic lockdowns set up 'natural experiment' on air pollution

By Carol Clark | eScienceCommons | April 7, 2020

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Graphic shows the change from January to February in China's levels of nitrogen dioxide, which primarily gets into the air from the burning of fuel by motor vehicles and power plants. (European Space Agency)

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For years, Eri Saikawa has tracked growing levels of dangerous greenhouse gases and researched ways to reduce them. As an associate professor in Emory’s Department of Environmental Sciences, she trains students to do the same. Together, they’ve held conferences, published papers and served as delegates at the annual U.N. global climate talks.

Now the COVID-19 lockdowns have slashed air pollution levels faster than Saikawa or her students could have imagined. First in China, where COVID-19 was reported in December, then across Europe, and now in the United States.

“It’s an interesting natural experiment, for sure,” says Saikawa, an expert in public policy and the science of emissions linked to global warming. “Since not every industry has shut down, it may help us to better understand what emissions are coming from what sources. That could help guide the best strategies to improve air quality when the pandemic is over.”

This natural experiment has now become the focal point for Saikawa’s class “Introduction to Atmospheric Chemistry.” Previously, the students were set to do outreach projects for the Atlanta Science Festival, at K-12 schools and in Atlanta neighborhoods. COVID-19 changed those plans as the festival and other events were cancelled and schools and universities shifted to remote learning. 

Saikawa is now asking her students to track current greenhouse gas emissions and air pollutants and compare them with levels for the same period in previous years, based on data from the U.S. Environmental Protection Agency, NASA and global sources.

“The students will be among the first to study this,” Saikawa says. “That’s so much different than answering questions from a textbook. When you’re doing actual science, unexpected things happen that open up new questions. The students will be taking on real questions as they come up in real time.”

At the end of the class, in early May, plans call for the students to hold a webinar so that anyone interested in learning how the novel coronavirus impacted air quality and climate change can tune in and learn from it.

The pandemic also affected projects of Saikawa’s graduate students in Asia. Her lab has collaborations with universities in Nanjing, China, Tokyo, Japan and Yongsei, South Korea. “Our focus was looking at air emissions in East Asia in relation to climate change,” Saikawa says. “Now we are broadening that to also look at how a pandemic affects air quality, climate and economies.” 

The researchers may be better able to pinpoint the impact of emissions from different sectors, including industries that are major users of fossil fuels, such as steel-making, oil, natural gas and mining; electricity and other sources of power; and transportation in the form of motor vehicles, shipping and tractors.

“China is the largest emitter in the world of carbon dioxide and most other air pollutants,” Saikawa says. Even with the dramatic drop in pollution, as China ground nearly to a halt following the initial outbreak of COVID-19, the country had dangerously high levels of air pollution on some days. “That shows that the background level of pollution is really high, and how far China needs to go to clean its air,” Saikawa says.

She worries that all the gains made around the world could boomerang into even worse conditions than previous norms if economies go into overdrive to recover. The 2020 U.N. climate talks, set for Scotland in November, have been postponed until 2021. The conference venue in Glasgow where the conference was to be held is now a field hospital for people with COVID-19.

And the U.S. Environmental Protection Agency recently announced a sweeping waiver of its enforcement of regulations, due to the pandemic.

“Those that are hardest hit by the effects of the pandemic are those who are the most vulnerable in society,” Saikawa says. “The suspension of environmental laws makes them even more vulnerable.”

Follow Eri Saikawa on Twitter: @esaikawa.