Studying How COVID Cleared the Air

If you’ve watched a traffic report since COVID-19 stay-at-home orders were issued back in March, you probably noticed something was missing—traffic.

For Atmospheric and Oceanic Science Professor Russell Dickerson and his research team at the University of Maryland, this presented a rare opportunity to answer an important question: When daily routines like commuting to work or school change, how does that impact air quality?

“Lots of scientists who worry about air quality and greenhouse gas emissions had that question simultaneously,” Dickerson said.

Since the COVID-19 lockdown began in March, he and his research team have been working with the National Oceanic and Atmospheric Administration (NOAA) to take airborne measurements of how the disruption of our daily schedules has affected air pollution in the D.C. metro area. 

Research scientist Xinrong Ren and graduate student Phillip Stratton, both from UMD’s Department of Atmospheric and Oceanic Science, regularly fly three-hour missions around the area on a small Cessna research aircraft equipped to gather real-time information on pollutants like carbon monoxide and ozone, and greenhouse gases such as methane and carbon dioxide.

On the ground, the team analyzes that data, along with wind and weather information, comparing them to measurements on days when traffic was normal. 

“Car traffic actually fell to about half of what it would typically be for a few weeks,” Dickerson said. “The idea was to take the measurements we had from February before the lockdown and in March, April and May, after the lockdown, and say, ‘Ok, what’s the difference?’”

Preliminary results show significant differences between air pollution levels before and after the lockdown, with both carbon dioxide and carbon monoxide down roughly 30% in March.

Even before the pandemic hit the U.S., NASA imagery foreshadowed the impact the coronavirus would have on air quality here.

“Before we knew that this was going to be a major disruption to the world’s economy, satellite observations were showing that air pollution over China just got dramatically better, and they had a very serious lockdown,” Dickerson said. 

Dickerson believes the aerial research, which has been underway for five years, plays an important role in policymaking and education. It may be months before Dickerson and his team have the final results from the current COVID-19 aerial studies, he said, but the research on how changes in our routines and driving habits can impact air quality could be crucial for transportation and environmental planning.

As stay-at-home orders are lifted and people start driving more, Dickerson’s team will continue to track the changes. He expects to see a return to normal levels for some of the pollutants in the air, but not anytime soon.

“The demand for electricity is down, gasoline sales are down, jet fuel sales are down, and I think it’s going to be a little while before we have business as usual,” Dickerson said. “Where we’ll be a year from now is anybody’s guess.”