April 10 (UPI) -- Air pollution has declined by as much as 30 percent in cities across the northeastern United States. With COVID-19 spreading across the country, mayors and governors have issued stay-at-home orders to slow transmission and protect residents.
The movements of residents throughout the Northeast have been restricted for more than two weeks, and many businesses have been closed for days. The reduction in transportation and commerce has resulted in significant improvements in air quality.
Scientists often use nitrogen dioxide as a proxy for the influence of human activity on air pollution. Nitrogen dioxide is mostly emitted via fossil fuel combustion for transportation and electricity production.
In March, NASA's Aura satellite and its Ozone Monitoring Instrument measured the lowest nitrogen dioxide concentrations across the Northeast since it began capturing data in 2005.
The latest NASA data showed the average nitrogen dioxide concentration up-and-down the I-95 corridor, from Washington, D.C., to Boston, was 30 percent lower than the average concentration measured between 2015 and 2019.
"Further analysis is required to rigorously quantify the amount of the change in NO2 levels associated with changes in pollutant emissions versus natural variations in weather," NASA wrote in an update.
The United States isn't the only place experiencing cleaner air.
In China, where the COVID-19 outbreak began and where some of the most extensive and restrictive lock-down measures were deployed, air pollution has dropped dramatically over the last few months. Some scientists have even surmised the reduction in air pollution, if only periodic, will likely save more lives in China than the virus killed.
Air pollution is responsible for the premature deaths of millions of people every year, including at least 100,000 deaths from lung and heart disease in the U.S.