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Impacts of Traffic Reductions Associated With COVID‐19 on Southern California Air Quality
Author(s) -
Parker H. A.,
Hasheminassab S.,
Crounse J. D.,
Roehl C. M.,
Wennberg P. O.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl090164
Subject(s) - air quality index , structural basin , environmental science , covid-19 , air pollution , physical geography , meteorology , geography , geology , medicine , outbreak , ecology , disease , pathology , virology , infectious disease (medical specialty) , biology , paleontology
On 19 March 2020, California put in place Stay‐At‐Home orders to reduce the spread of SARS‐CoV‐2. As a result, decreases up to 50% in traffic occurred across the South Coast Air Basin (SoCAB). We report that, compared to the 19 March to 30 June period of the last 5 years, the 2020 concentrations of PM 2.5 and NO x showed an overall reduction across the basin. O 3 concentrations decreased in the western part of the basin and generally increased in the downwind areas. The NO x decline in 2020 (approximately 27% basin‐wide) is in addition to ongoing declines over the last two decades (on average 4% less than the − 6.8% per year afternoon NO 2 concentration decrease) and provides insight into how air quality may respond over the next few years of continued vehicular reductions. The modest changes in O 3 suggests additional mitigation will be necessary to comply with air quality standards.