Climate Science and Policy

COVID-19 policies impacted fine particulate matter (PM2.5 ) levels in San Diego County. This study looked at the benefits of COVID-19-related policies and changes in PM2.5 levels across ZIP codes in San Diego County. Weekly PM2.5 anomalies were calculated for each ZIP code by subtracting the average PM2.5 concentrations of 2020 by average of the historical period (2000 - 2019). Five periods were selected for individual analyses based on the different COVID-19 policies and measures implemented. These policies involved the first stay-at-home order (analysis #1), summer restrictions (analysis #2), the second stay-at-home order (analysis #3), the average of analyses 1-3, (analysis #4), and the wildfire season (analysis #5). PM2.5 anomalies and seven different socioeconomic status (SES) variables were mapped to show any spatial variability. Linear regression models were used to quantify the relationship between SES variables and PM2.5 anomalies for each analysis. The first stay-at-home order (analysis #1) had the lowest PM2.5 anomalies across the County. Analysis #5, on the other hand, had the highest positive anomalies. COVID-19 mobility restrictions and the associated short-lived decline in air pollution influenced the ZIP codes differently. South San Diego County is a greatly disadvantaged area with high unemployment rate, low income, high poverty rate, and less education compared to others within the County. A significant inverse relationship was observed between the percentage of African American within a given ZIP code and PM2.5 anomalies. Future policies need to tackle health disparities, which involves stringent policies, a better public transit system, community advocacy, and cleaner technology.