Tree Canopy Cover and Injurious Pedestrian Falls: A Location-Based Case-Control Study.

Abstract

Despite about half a million injurious pedestrian falls occurring annually in the US, prevention of pedestrian falls is under studied. Sidewalk damage from street trees is a known risk for falls, however tree canopy cover might reduce falls in summer months by lowering ambient temperatures. We conducted pilot research to assess whether Emergency Medical Services (EMS) data could be used to implement a multi-city, location-based case-control study investigating the association between tree canopy cover and locations of injurious pedestrian falls. Case locations (n=497) were places where EMS responded to a pedestrian fall occurrence between April and September of 2019. Matched control locations (n=994) were selected from intersections, street segments, and ramp segments that existed in 2019. Percent tree canopy cover was measured within a 100-m radial buffer of each location. Median tree canopy coverage at fall locations was 8%, compared to 14% for control locations. In adjusted analyses, higher tree canopy cover was inversely associated with fall locations (adjusted OR across the inter-quartile range of canopy cover = 0.57, 95% CI:0.45-0.74), suggesting higher tree canopy cover is associated with lower pedestrian falls risk. Methodological challenges and solutions to implementing and interpreting the location-based, case-control design with EMS data are discussed.