Trends in philadelphia asthma encounters and pollution during the COVID-19 pandemic

Rationale: The COVID-19 pandemic dramatically changed daily routines as well as healthcare utilization and delivery patterns in the United States. We sought to identify changes in pediatric asthma-related healthcare utilization and levels of air pollution i.e. particulate matter (PM2.5, PM10) and gaseous chemicals (NO2, O3) during the COVID-19 pandemic in Philadelphia. We hypothesized that declining utilization of asthma care and changed pollution levels during the early stages of the pandemic rebounded after the relaxation of COVID-19-related public health measures. Methods: For the time period Mar 17 to Dec 17 during the years 2015-2020, asthmarelated encounters and weekly summaries of respiratory viral testing data were extracted from Children's Hospital of Philadelphia (CHOP) electronic health records. Daily average estimates of PM2.5, PM10, O3, and NO2 for the same time period were obtained from AirData, an EPA resource that provides quality-assured summary air pollution measures collected from outdoor regulatory monitors across the United States. Patterns in encounter characteristics and viral testing in Philadelphia from Mar 17 to Dec 17, 2020, were compared to data from 2015-2019 as a historical reference. Encounter pattern results were summarized as percentage changes. Controlled interrupted time series regression models were created to identify statistically significant differences in pollution levels that differed in 2020 compared with historical time periods. Results: We present data on asthma encounters, viral testing, and air pollution from Mar 2020 through Dec 2020. Contrary to the early stages of the pandemic when in-person asthma encounters decreased by 87% (outpatient) and 84% (emergency + inpatient), asthma-related encounters rebounded with the relaxation of COVID-19-related public health measures. During the initial months of the pandemic, the daily average of PM2.5, PM10, and NO2 levels decreased by 29.0% (2.17 μg/m3), 18.2% (3.13 μg/m3), and 44.1% (6.75 ppb), respectively, whereas ozone levels increased by 43.4% (10.08 ppb), changes that were not statistically significantly different compared to historical trends. Levels of all pollutants considered remained similar during subsequent 2020 months compared to the 2015-2019 reference period. Conclusion: The COVID-19 pandemic in Philadelphia was accompanied by initial decreases in pediatric asthma healthcare activity. Concurrent with the relaxation of COVID-19-related public health measures, there was a subsequent increase in asthma healthcare activity. No substantial change in air pollution levels compared with historical patterns was observed during the time period considered, suggesting that other factors influenced changes in asthma trends during the COVID-19 pandemic.