Higher levels of tree canopy cover may help prevent injurious pedestrian falls, according to a new study led by researchers at Columbia University Mailman School of Public Health in New York City. They found that during summer months, streets and sidewalks where pedestrians fell and experienced an injury were less likely to be shaded by trees than matched control locations.

While indoor falls have been well studied, outdoor pedestrian falls have received far less attention, despite accounting for about half a million injurious incidents in the US each year, according to the researchers. Walking has multiple health benefits, and the findings provide new evidence that urban greenery, perhaps through cooling the local ambient environment, contributes to pedestrian safety.

Researchers analyzed data on tree canopy cover at 497 locations where Emergency Medical Services attended to pedestrians injured in a fall between April and September 2019 and at 994  matched control locations. Tree canopy cover at each location where an injurious fall occurred and at matched control locations was measured using the 2019 National Land Cover Database—the national gold standard for canopy assessment.

Average tree canopy cover at fall locations was 8%, compared with 14% at control sites. Higher tree canopy cover was strongly inversely associated with locations where a pedestrian fall occurred after controlling for neighborhood socioeconomic factors and proxy measures for pedestrian volume.

“Sidewalk-related injuries represent a substantial public health burden,” said senior author Andrew Rundle, DrPH. “Unlike indoor falls, which are often linked to personal health factors, outdoor falls are shaped by environmental conditions. Our findings suggest that tree cover, by lowering ambient temperatures, may help reduce fall risk.”

The researchers note that while outdoor fall risk is well known to be associated with snow and ice, emerging data suggest that high temperatures can increase fall risk by adversely affect human physiology and by degrading road and sidewalk surfaces. High heat softens asphalt and causes sidewalk pavement to pop out of alignment, creating trip and fall hazards.

To download a pdf of the study, published in the American Journal of Epidemiology, click here