Pediatric Heat Stress Injuries and Death in Vehicle Trunk Entrapments: Internal Trunk Temperatures Can Rapidly Reach Lethal Levels

Abstract

Over the last 15 years, more than 500 children have died in the United States after being trapped in the hazardous conditions within motor vehicles. Most of these deaths involved children left unattended in the cabin of enclosed vehicles on warm-to-hot days. Previous studies indicate that internal cabin temperatures can quickly rise well above 100°F (37.8°C), even if the outside environment is relatively mild. In a 100°F (37.8°C) setting with moderate relative humidity (>50%), children can rapidly overheat and develop heat stroke. Dangers associated with the deaths of children in motor vehicle entrapment have been well-studied and well-reported, increasing both the involvement of policy-makers and public awareness. While less publicized and certainly less studied, unintentional trunk entrapments account for nearly 10% of these reported deaths. Some of these deaths resulted from hyperthermia while others were classified as a combination of hyperthermia and asphyxiation. To date, no study has analyzed conditions within a trunk. The objective of this study is to investigate the magnitude and rate of temperature rise within a discontinuous trunk over a range of mild and hot environmental temperatures. For comparison, we simultaneously measured cabin temperatures. We also applied thermal tolerance information to the data in order to estimate the minimum time required for the trunk and cabin to reach dangerous temperatures. Trunk temperatures increased 15.5-22.2°F (8.6-12.3°C), meaning that the trunk quickly heated to lethal levels on warm-to-hot days. However, the trunk failed to reach lethal temperatures on cooler days. Applying this new information concerning trunk temperatures helps explain why asphyxiation is occasionally a factor in trunk entrapment fatalities. Because trunk temperatures were at least 15.2°F cooler than the cabin, the effects of hyperthermia are delayed enough in some cases to allow a trapped child to consume the oxygen within the trunk. Despite the preventative efforts of law-makers and vehicle manufacturers, incidents of entrapped children continue to occur. Increasing public and guardian awareness of the dangers of leaving a child unattended in or around motor vehicles may help reduce deaths due to cabin or trunk entrapment. Establishing an official record system of deaths resulting from trunk or cabin entrapment would help identify common underlying causes and would better equip law-makers, educators, and manufacturers in preventing vehicle entrapment.