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COVID‐19 Induced Fingerprints of a New Normal Urban Air Quality in the United States
Author(s) -
Kondragunta S.,
Wei Z.,
McDonald B. C.,
Goldberg D. L.,
Tong D. Q.
Publication year - 2021
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2021jd034797
Subject(s) - air quality index , troposphere , covid-19 , environmental science , atmospheric sciences , unemployment , meteorology , tropospheric ozone , geography , agricultural economics , economic growth , economics , medicine , geology , disease , pathology , infectious disease (medical specialty)
Most countries around the world, including the United States, took actions to control COVID‐19 spread that led to an abrupt shift in human activity. On‐road NO x emissions from light and heavy‐duty vehicles decreased by 9%–19% between February and March at the onset of the lockdown period in the middle of March in most of the US; between March and April, the on‐road NO x emissions dropped further by 8%–31% when lockdown measures were most stringent. These precipitous drops in NO x emissions correlated well ( r = 0.75) with tropospheric NO 2 column amount observed by the Sentinel 5 Precursor TROPOspheric Monitoring Instrument (S5P TROPOMI). Furthermore, the changes in TROPOMI tropospheric NO 2 column amount across continental US between 2020 and 2019 correlated well with the changes in on‐road NO x emissions ( r = 0.68) but correlated weakly with changes in emissions from the power plants ( r = 0.35). At the height of lockdown‐related unemployment in the second quarter of 2020, the tropospheric NO 2 column values decreased at the rate of 0.8 µmoles/m 2 per unit percentage increase in the unemployment rate. Despite the lifting of lockdown measures, parts of the US continued to have ∼20% below normal on‐road NO x emissions. To achieve this new normal urban air quality in the US, continuing remote work policies that do not impede economic growth may become one of the many options.