Quantifying the Heat-Related Hazard for Children in Motor Vehicles

Abstract

Thirty-seven children on average die each year in the United States from vehicle-related hyperthermia. In many cases, the parent or care-giver intentionally left the child unattended in the car, unaware of how quickly temperatures may reach deadly levels. To better quantify how quickly temperatures may increase within a car, maximum rates of temperature change were computed from data collected on 14 clear days in Athens, Georgia. Also, a human thermal exchange model was used in a case study to investigate the influence of different meteorological factors on the heat stress of a child in a hot vehicle. Results indicate that a car may heat up by approximately 4°C in 5 min, 7°C in 10 min, 16°C in 30 min, and 26°C in 60 min. Within the vehicle, the dominant energy transfers toward the child are via longwave radiation and conduction from the hot interior surfaces of the car. Modeling simulations show that sun exposure and high-humidity conditions further increase the heat stress on the child but that a negative feedback involving evaporated perspiration reduces the influence of variations in humidity on net heat storage. Last, a table of vehicle temperature changes is included that may help public officials and the media communicate the dangers of vehicle-related hyperthermia in children.