Relationships between Local Vegetation Level and Human Mobility Patterns during COVID-19 for Maryland, USA

Abstract

Background: Human mobility is a significant factor for disease transmission. Little is known about if built environment influence mobility during the COVID-19 pandemic. We investigated a potential effect of local vegetation level on mobility reductions during the COVID-19 pandemic in Maryland, USA. Methods: Our study regions included 193 minor civil divisions (MCDs) in Maryland. We obtained mobility data from Facebook Data for Good, which aggregate information of people using Facebook app on their mobile phones with location history active. The user’s movement between two locations during a given time window at the 4.9km by 4.9km spatial scale was used to calculate the number of users traveled into a region for each day between March 11, 2020 and April 26, 2020. The mobility change for a region for each day was estimated as percent change in the number of users traveling into that region in the daytime (8am - 4pm) compared to the average number of users traveled into that region during the same daytime window and the same day of the week between February 24, 2020 and March 10, 2020. Each MCD’s vegetation level was estimated as the average Enhanced Vegetation Index level through January 1, 2020 and March 31, 2020. Results: Among 193 study regions, user’s movement were observed in 53 regions, which had higher population and percent impervious area. The daily percent changes in the number of users traveling into those 53 regions declined during the study period. This mobility reduction was significantly higher in regions with the lowest level of EVI indicating lower vegetation level (p-value=0.041). Conclusions: Mobility reduction during the COVID-19 pandemic in Maryland was less in regions with higher vegetation level. Future studies will need to investigate changes in health effects of green space during a pandemic and who are disproportionately affected by such changes.