Graduation Year


Date of Submission


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Kathleen Purvis-Roberts

Reader 2

Franck Fu

Rights Information

@2020 Tanner J Cress


The COVID-19 pandemic caused many industries and public transportation, resulting in lower vehicle miles travelled in public and private sectors, to temporarily shut down as stay-at-home orders were implemented in an attempt to control the spread of the virus. In order to determine if there was a significant change in air quality in the United States in response to these restrictions, Environmental Protection Agency (EPA) pollutant concentration data for PM2.5, ozone, and NO2 was analyzed from 2015 to 2020 in 31 locations during the stay-at-home order timeframes issued on state or county levels. Cities were selected based upon 1) having historically poor air quality or 2) being representative of the entire U.S. geographically. Rural counties were chosen in the same states as selected cities, when data was available, to compare changes in air pollution in rural and urban settings. Weather conditions were analyzed as well to determine if changes in air quality can be attributed to COVID-19 shutdowns or environmental factors. Results show that, on average across all locations, PM2.5 decreased by 7.0%, ozone by 2.3%, and NO2 by 17.9%. Twenty-one locations exhibit decreasing PM2.5 concentrations while 22 locations had lower ozone concentrations. NO2 showed reductions in all locations. In addition, findings showed that PM2.5 decreased more in areas with stay-at-home orders than without, but the opposite was the case with ozone. For PM2.5, urban locations experienced more reductions than rural areas, while rural areas experienced a greater decrease in ozone concentrations. The meteorological conditions also played key role. For instance, higher rainfalls in 2020 corresponded with lower PM2.5 concentrations in locations such as Los Angeles.

This thesis is restricted to the Claremont Colleges current faculty, students, and staff.