The top image is the average concentration of nitrogen dioxide in March of 2015-19, while the bottom image shows the average concentration measured in March of this year.
The top image is the average concentration of nitrogen dioxide in March of 2015-19, while the bottom image shows the average concentration measured in March of this year.


If there are any small silver linings to come out of the COVID-19 pandemic and lockdown, one of them is that air quality has improved. But whether that improvement remains after we get back to the new normal is up for debate. 

Over the past several weeks, NASA satellite measurements have revealed significant reductions in air pollution over New York and New Jersey, similar to the reductions observed in other regions of the world where the pandemic has caused normal life to shut down. 

Although New York went on total lockdown in mid-March and New Jersey a week later, many businesses had already closed or allowed employees to work from home. 

With fewer cars and buses on the streets, levels of nitrogen dioxide (NO2), primarily emitted from the burning of fossil fuels for transportation and electricity generation, have lowered substantially. 

“These recent improvements in air quality have come at a high cost, as communities grapple with widespread lockdowns and shelter-in-place orders as a result of the spread of COVID-19,” Peter Jacobs, of NASA’s earth public affairs (acting), wrote in an announcement made last week.

Nitrogen dioxide levels can also be used as an indicator of changes in human activity.

The atmospheric nitrogen dioxide was measured by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite.

Satellite images gathered by NASA spanning five years show March 2020 to have the lowest monthly atmospheric NO2 levels of any March during the time span. The data collected indicate that the nitrogen dioxide levels in March 2020 were about 30 percent lower on average across the region of the I-95 corridor — from Washington, D.C., to Boston — than the March mean of 2015-19, according to NASA. 

Nitrogen dioxide levels observed from space serve as an effective proxy for NO2 levels at Earth’s surface, though there will likely be differences in the measurements from space and those made at ground level. It is also important to note that satellites that measure nitrogen dioxide cannot see through clouds, so all data shown is for days with low cloudiness. 

Dirk Vanderklein, Ph.D., the chairperson of Montclair State University’s Department of Biology, said that in the short term, fewer cars and buses on the streets is a good thing. 

“NO2 also plays a part in the production of ozone,” he said. “Ozone in the upper atmosphere is good for us because it blocks UV radiation. Ozone in the lower atmosphere where we breathe is bad for us because it damages lung cells and leaf cells. So, the reduction in NO2 should also mean a reduction in ozone in our breathing air, which is also a good thing for animals and plants.”

Vanderklein says that in the long term, a couple of low-level nitrogen dioxide months won’t really matter. And if people are required to report to work while the pandemic is in full effect, it’s possible that commuters will feel safer driving their own vehicles, rather than taking public transportation on crowded trains or buses.

However, the “new normal” could make a difference, if more employers allow people to work from home and more people continue walking on errands rather than getting into vehicles. 

Gray Russell, Montclair’s sustainability officer, said commuters are limited to public transportation because driving to the city during rush hour could take two hours. He thinks more corporations will be willing to allow employees to work from home and to hold meetings through webinars.

“This event has exaggerated that you don’t need to drive to a meeting and that employees can work from home and be very productive,” he said. 

In addition, he said, companies facing economic downturns due to the virus may want to lose the cost of real estate and overhead and have employees work remotely. 

Another good thing that has come from the pandemic, Russell said, is that people are looking for healthier lifestyles. More people are walking, the number of shoppers at the open-air farmers market has doubled, and more people are growing their own vegetables at home. 

“It all depends on if these things become habits. We will know better in six to 12 months,” he said.