Special Issue on Air Quality in a Changed World: Regional, Ambient, and Indoor Air Concentrations from the COVID to Post-COVID Era

Sara McElroy  This email address is being protected from spambots. You need JavaScript enabled to view it.1,2, Ambarish Vaidyanathan2

1 Oak Ridge Institute for Science and Education, Oak Ridge, TN USA and Climate and Health Program, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
2 Climate and Health Program, DEHSP, NCEH, CDC, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA

Received: January 27, 2022
Revised: June 21, 2022
Accepted: August 31, 2022

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.220047  

Cite this article:

McElroy, S., Vaidyanathan, A. (2022). Understanding Air Quality Changes After Implementation of Mitigation Measures during a Pandemic: A Scoping Review of literature in the United States. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.220047


  • The effects of pandemic mitigation practices on air quality were heterogeneous across the US.
  • We saw a reduction in NO2 and CO and inconclusive trends for other air pollutants.
  • Only a few studies evaluated changes by examining mobility and traffic flow patterns.


Traffic-related emissions continue to be a significant source of air pollution in the United States (US) and around the globe. Evidence has shown that previous policies implemented to restrict-traffic flows have affected air pollution levels. Thus, mitigation strategies associated with the COVID-19 pandemic that modified population-level mobility patterns provide a unique opportunity to study air pollution change across the US. For instance, to slow the spread of the pandemic, state and local governments started implementing various mitigation actions, including stay-at-home directives, social distancing measures, school closures, and travel restrictions. This scoping review aimed to summarize the existing evidence about how air quality changed through mitigation practices throughout the pandemic in the US. We found 66 articles that fit our inclusion criteria. Generally, the consolidated results revealed that nitrogen dioxide (NO2) and carbon monoxide (CO) decreased across the country. Studies observed mixed directions and magnitudes of change for fine and coarse particulate matter (PM2.5, PM10), ozone (O3), and sulfur dioxide (SO2). Few articles tried to explain this notable heterogeneity in air quality changes by associating contextual factors, such as mobility, traffic flow, and demographic factors. However, all studies agreed that the change in air pollution was nonuniform across the US and even varied within a city.

Keywords: COVID-19, Air pollution, Mitigation measures, Mobility, Public health interventions

Share this article with your colleagues 


Subscribe to our Newsletter 

Aerosol and Air Quality Research has published over 2,000 peer-reviewed articles. Enter your email address to receive latest updates and research articles to your inbox every second week.

Aerosol and Air Quality Research (AAQR) is an independently-run non-profit journal that promotes submissions of high-quality research and strives to be one of the leading aerosol and air quality open-access journals in the world. We use cookies on this website to personalize content to improve your user experience and analyze our traffic. By using this site you agree to its use of cookies.