Associations between pedestrian fatalities and air temperature, United States, 2001-2021

Pedestrian injuries killed almost 9000 Americans in 2021. Pedestrian fatality rates have increased annually since 2009. Many factors are associated with pedestrian fatalities, but one poorly-understood risk is the role of climate. We examined two primary sets of associations, those between pedestrian fatality crude rate (deaths per 100,000 population) and air temperatures in each US state (2012-2021) and those between national air temperatures and pedestrian fatality crude rate in each year from 2001-2021.

Data were obtained from public-facing CDC WISQARSTM and NOAA Climate-at-a-Glance websites. Descriptive and correlational analyses were conducted.

Average air temperatures in individual US states correlated with pedestrian fatality crude rates in those states, r = 0.66. National average annual temperatures correlated with annual pedestrian fatality crude rates each year, r = 0.61. Secondary analyses considering correlations between annual pedestrian fatality crude rates and heating degree days, cooling degree days, and grid days over 70° F replicated primary results. Secondary analyses considering change in temperature from the previous year and pedestrian fatality crude rates were null.

US pedestrian fatality crude rates are associated with air temperatures. Causality cannot be assumed, but possible explanations for the association include increased exposure to traffic during daytime walking in cooler climates and increased exposure to risk through more walking at night in warmer climates. If findings were translated into NOAA-estimated climate change scenarios of 1° of temperature change over 30 years, correlational associations from the past two decades maintained unchanged, and population presumed stable, between 430-755 additional pedestrian fatalities could occur annually in the future.