In previous urban ecology experiments at CAP LTER, the goal was to find effective city designs that decrease the intensity of summer temperatures within the city and negative direct or indirect effects to people, animals, and plants.
The main concerns within urban ecological research and the impacts of extreme heat on humans involves the direct hazard of high heat loads on humans. One solution involves technological and infrastructural approaches to help populations remain aware of extreme heat and the impacts to health. For example, the use of shade in urban areas is a promising heat mitigation technique and creating models specific to a health endpoint (injury or death) can provide more actionable information. Providing such information will help policy and decision makers, as well as engineers, take advantage of information to create safer urban spaces. The current project addresses an important urban health issue concerning the high number of deaths of infants and toddlers left in hot cars. Through human heat balance modeling and in-vehicle measurements on shaded and sun-exposed parking lots, we estimated the core temperature response of a model 2-year old toddler over three hot summer days in six cars in Tempe, Arizona.
The results show that 63% of the trials for the sun-exposed cars lead to a core temperature of ≥ 40°C (which represents heat stroke and potential death) in the modeled child. None of the core temperature calculations in the shaded cars reached 40°C during the same time period. Overall results indicate modeled core temperatures reached 38.5°C (heat injury likely) in 87% of the modeled cases in 60 min or less, in both the sun and shade. In sun-exposed cars, the core temperatures surpassed the value of 38.5°C in all trials over only <15 minutes on average. There was no significant difference by car type or color. Any instance is unsafe to leave a child in a car for any period of time on warm-hot days due to the magnified heating dynamics of vehicles and enhanced heat vulnerability of children. Such findings also reinforce the need for heat mitigation policy and proper messaging along with related behavioral or technological prevention initiatives.