The impact of COVID-19-induced lockdowns during spring 2020 on nitrogen dioxide levels over major American counties

James Poetzscher,Rima J Isaifan

doi:10.1525/elementa.2021.00002

James Poetzscher, Rima J Isaifan

Open Access

https://doi.org/10.1525/elementa.2021.00002

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Abstract

COVID-19 has quickly spread throughout the world, infecting and killing millions of people. In an effort to contain the spread of the virus, many governments implemented stringent lockdown measures. These lockdown restrictions, coupled with social distancing, severely curtailed transportation and industrial activities, which are the primary drivers of nitrogen oxides emissions. This study investigates whether lockdown orders in the United States have impacted tropospheric nitrogen dioxide (NO2) levels by evaluating 12 major counties with a total population of 38 million. For each county, Sentinel-5P satellite data were obtained and analyzed to determine NO2 column concentrations during the pre-lockdown, peak lockdown, and loosening lockdown periods in 2020. Then, NO2 levels were compared during these three periods to the same time frame in 2019. Our results show that the lockdowns in the 12 major U.S. counties analyzed led to a significant decline in NO2 levels, with an average reduction of 28.7% (±14.6%) and 17.6% (±10.9%) during peak lockdown and loosening lockdown periods, respectively.

Highlights

In late December 2019, a novel coronavirus (COVID-19) emerged in Wuhan and began spreading rapidly around the world (Isaifan, 2020)
Given that many major regions of the United States enacted stringent lockdowns that curbed human activity as discussed earlier, and resulted in a 41% decrease in traffic levels in April 2020, it was interesting to explore whether similar declines in air pollution, as seen in China, India, and Western Europe, would be observed in major American cities during the COVID-19 lockdowns (U.S Department of Transportation, 2020)
In an attempt to determine whether a significant decline in NO2 pollution occurred during America’s COVID-19 lockdowns, tropospheric NO2 column densities were analyzed in 12 major American counties during the peak lockdown and loosening lockdown periods in 2020, and compared to NO2 levels prior to lockdown in 2020 and to the corresponding periods in 2019

Summary

Introduction

In late December 2019, a novel coronavirus (COVID-19) emerged in Wuhan and began spreading rapidly around the world (Isaifan, 2020). As COVID-19 spread to other nations in Asia, Europe, and the United States of America, similar lockdowns were enacted to curb the virus’s rapid spread (Kontis et al, 2020) These large-scale lockdowns severely restricted anthropogenic activity responsible for air pollution, such as the operation of individual vehicles, energy consumption, and industrial activity (Menut et al, 2020). Given that many major regions of the United States enacted stringent lockdowns that curbed human activity as discussed earlier, and resulted in a 41% decrease in traffic levels in April 2020, it was interesting to explore whether similar declines in air pollution, as seen in China, India, and Western Europe, would be observed in major American cities during the COVID-19 lockdowns (U.S Department of Transportation, 2020). In an attempt to determine whether a significant decline in NO2 pollution occurred during America’s COVID-19 lockdowns, tropospheric NO2 column densities were analyzed in 12 major American counties during the peak lockdown and loosening lockdown periods in 2020, and compared to NO2 levels prior to lockdown in 2020 and to the corresponding periods in 2019

Material and methods

Results and discussion

Findings

Conclusion