title: Evaluating infant core temperature response in a hot car using a heat balance model.
abstract: OBJECTIVE
  Using a 1-year old male infant as the model subject, the objectives of this study were to measure increased body temperature of an infant inside an enclosed vehicle during the work day (8:00 am-4:00 pm) during four seasons and model the time to un-compensable heating, heat stroke [>40 °C (>104 °F)], and critical thermal maximum [>42 °C (>107.6 °F)].
  
  
  METHODS
  A human heat balance model was used to simulate a child's physiological response to extreme heat exposure within an enclosed vehicle. Environmental variables were obtained from the nearest National Weather Service automated surface observing weather station and from an observational vehicular temperature study conducted in Austin, Texas in 2012.
  
  
  RESULTS
  In all four seasons, despite differences in starting temperature and solar radiation, the model infant reached heat stroke and demise before 2:00 pm. Time to heat stroke and demise occurred most rapidly in summer, at intermediate durations in fall and spring, and most slowly in the winter. In August, the model infant reached un-compensable heat within 20 min, heat stroke within 105 min, and demise within 125 min. The average rate of heating from un-compensable heat to heat stroke was 1.7 °C/h (3.0 °F/h) and from heat stroke to demise was 4.8 °C/h (8.5 °F/h).
  
  
  CONCLUSIONS
  Infants left in vehicles during the workday can reach hazardous thermal thresholds quickly even with mild environmental temperatures. These results provide a seasonal analogue of infant heat stroke time course. Further effort is required to create a universally available forensic tool to predict vehicular hyperthermia time course to demise.
authors.affiliation: Department of Geography, The University of Georgia, Geography-Geology Bldg, 210 Field Street, 30602, Athens, Georgia, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Grundstein
authors.forename: Sarah V
authors.initials: SV
authors.lastname: Duzinski
authors.forename: David
authors.initials: D
authors.lastname: Dolinak
authors.forename: Jan
authors.initials: J
authors.lastname: Null
authors.forename: Sujit S
authors.initials: SS
authors.lastname: Iyer
mesh_terms: D000367:Age Factors; D001336:Automobiles; D001833:Body Temperature Regulation; D002423:Cause of Death; D003020:Clothing; D003198:Computer Simulation; D005334:Fever / Q000209:etiology / Q000401:mortality* / Q000503:physiopathology*; D018882:Heat Stress Disorders / Q000209:etiology / Q000401:mortality* / Q000503:physiopathology*; D018869:Heat-Shock Response; D006358:Hot Temperature; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D008297:Male; D008954:Models, Biological; D018570:Risk Assessment; D012307:Risk Factors; D012621:Seasons; D013997:Time Factors