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Atmospheric Chemistry

COVID-19 coronavirus quarantines cause rapid drop in air pollution

NO2 levels have fallen sharply in northern Italy and China

by Katherine Bourzac
March 21, 2020 | A version of this story appeared in Volume 98, Issue 11


A satellite image of NO2 levels in Italy.
Credit: Copernicus Atmosphere Monitoring Service (CAMS); ECMWF
By Feb. 2, NO2 levels over northern Italy (red patch) had already begun decreasing. Hot spots are shown in white in this colorized satelllite image; lower levels are darker red.

Satellite data from the European Commission’s Copernicus Atmosphere Monitoring Service have confirmed a sharp decline in ground-level nitrogen dioxide air pollution in northern Italy since Jan. 30, when officials confirmed the country’s first cases of COVID-19, the disease caused by the novel coronavirus. NO2 levels fell by about 10% each week as people left home less often and Italy began a lockdown March 9. As of C&EN’s press time, levels had fallen by a total of about 50%. Similar trends were seen earlier in the year in China. Vincent-Henri Peuch, who leads the Copernicus team, says declines are probably happening in other regions as the pandemic spreads. NO2 is a by-product of combustion and is emitted by cars, power plants, and industrial facilities. The gas is harmful to human health and reacts to form unhealthy ozone and particulate matter. There are a few historic equivalents to the dramatic change in air quality that has followed the economic slowdown caused by the pandemic, Peuch says. During the 2008 Beijing Olympics, local emission sources were banned, causing a distinct—if short-lived—improvement in air quality. For Peuch, the current situation also resembles the sharp reduction in sulfur dioxide when power plants in East Germany were equipped with scrubbers after the Berlin Wall fell.

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