Evaluating infant core temperature response in a hot car using a heat balance model

Area of Science:

• Pediatric environmental health
• Thermoregulation and heat stress physiology
• Forensic science and environmental risk assessment

Background:

• Vehicular heatstroke is a significant cause of infant mortality.
• Understanding the time course of hyperthermia in enclosed vehicles is critical for prevention.
• Seasonal variations in ambient temperature and solar radiation influence internal vehicle temperatures.

Purpose of the Study:

• To model the time to critical thermal maximum, heat stroke, and demise in an infant inside an enclosed vehicle.
• To assess these risks across four seasons during typical work hours (8:00 am–4:00 pm).
• To use a 1-year-old male infant as the model subject for physiological response.

Main Methods:

• Utilized a human heat balance model to simulate infant physiological responses.
• Incorporated environmental data from the National Weather Service.
• Used observational vehicular temperature data from Austin, Texas (2012).

Main Results:

• The model infant reached heat stroke and demise before 2:00 pm in all four seasons.
• Heat stroke and demise occurred fastest in summer, followed by fall and spring, and slowest in winter.
• In August, critical thresholds were reached within 20 minutes to 2 hours.

Conclusions:

• Infants are at rapid risk of hazardous thermal thresholds in vehicles, even in mild conditions.
• The study provides a seasonal model for infant heat stroke progression.
• Development of a universal forensic tool to predict vehicular hyperthermia is needed.