Expert Commentary

Child deaths in hot cars: Data and research

We've updated this research roundup with new data and studies, including a study that finds authorities have pursued criminal charges in 58.2% of cases of kids dying of vehicular heatstroke.

child death hot cars research
(Flickr/Joseph Novak)

This collection of research on child deaths in hot cars, originally published in June 2017, has been updated with recent studies on what these cases have in common and how brain structures may interact to cause parents and other caregivers to forget children in vehicles. 

Dozens of children die in the U.S. every year after being left alone in parked cars, where temperatures can rise rapidly even on cool days. In 2021, 23 kids died of vehicular heatstroke, according to the National Highway Traffic Safety Administration.

Since May, news outlets have chronicled the deaths of at least 10 youngsters, including a 1-year-old girl found unresponsive in a hot car parked outside her father’s workplace in North Carolina and a 5-year-old Texas boy who remained strapped in a car seat in his  family’s driveway while his mother prepared for a party.

In many states, it’s illegal to leave children unattended in a vehicle. But parents, grandparents and other caregivers sometimes forget they’re in the back seat and leave them there for hours.

Late last year, Congress included a mandate within its sweeping Infrastructure Investment and Jobs Act that requires new automobiles weighing less than 10,000 pounds to be equipped with a system that reminds drivers to check the back seat after the engine is turned off. That part of the federal law doesn’t take effect until late 2023, however.

To help journalists report on this topic, we’ve gathered several key studies and reports, including research that examines the conditions inside cars that contribute to heat stroke and the psychological processes that can cause loving and attentive parents to forget their kids in hot cars.

Another helpful resource for journalists is, a website run by meteorologist Jan Null, who researches child deaths in parked cars and tracks news coverage of them. Some of the advocacy groups trying to raise awareness of the problem are and Safe Kids Worldwide.


Pediatric Heatstroke Fatalities Caused by Being Left in Motor Vehicles
Hammett, Deborah L.; et al. Pediatric Emergency Care, December 2021.

Researchers analyzed 541 cases of children dying after being left in hot vehicles from Jan. 1, 2000 to Dec. 31, 2016, 528 of which involved one child and 13 of which involved two or more. Deaths were documented in 45 states. Most were accidental and occurred in home driveways and apartment complex parking lots. The authors find that heat-related deaths rose over the course of their 26-year study period. They also note authorities pursued criminal charges in 58.2% of cases.

Understanding memory loss

When a Child Dies of Heatstroke After a Parent or Caretaker Unknowingly Leaves the Child In a Car: How Does It Happen and Is It a Crime?
Diamond, David M. Medicine, Science and the Law, March 2019.

In this journal article, David Diamond, a professor of psychology, molecular pharmacology and physiology at the University of South Florida, explains how human memory works, factors that contribute to memory failure and why loving, attentive parents and caretakers sometimes forget young children in hot vehicles. “Just as a detective can forget his weapon in a public bathroom and a pilot can forget to set the wing flaps properly prior to take-off, a parent or caretaker can forget a child in a car, which puts the child at risk of harm from heatstroke,” Diamond writes. He also explains why he thinks a person who unknowingly and unintentionally left a child in a car should not be charged with a crime.

Estimates of child deaths

Retrospective Analysis of Heat Stroke Deaths of Children in Motor Vehicles
National Center for Statistics and Analysis. Traffic Safety Facts Research Note, December 2015.

This report explains why numbers released by the NHTSA for heat-stroke related deaths of children are generally lower than what is reported by other sources. The NHTSA collects information from death certificates. For children who died of suspected heat stroke, the official cause of death is sometimes listed as “fever, unspecified” or “assault (homicide) by other specified means” or “neglect and abandonment.” These children would not be included in the NHTSA’s tally of children who died of heat stroke in parked vehicles.

Not-in-Traffic Surveillance: Non-Crash Fatalities and Injuries
National Center for Statistics and Analysis, Traffic Safety Facts Research Note, March 2015.

Summary: “This Research Note provides updated information on fatalities and injuries among the overall population as well as among children 14 and younger who were involved in ‘motor vehicle non-crash incidents’ (herein referred to as non-crash incidents). The data on such incidents are obtained by the National Highway Traffic Safety Administration (NHTSA) through its Not-in Traffic Surveillance system. These updates reflect non-crash fatality data from 2005 to 2007 and injury estimates in 2011 and 2012.”

Circumstances leading to death

Hyperthermia Deaths Among Children in Parked Vehicles: An Analysis of 231 Fatalities in the United States, 1999–2007
Booth III, John N.; Davis, Gregory G.; Waterbor, John; McGwin Jr., Gerald. Forensic Science, Medicine, and Pathology, 2010.

Abstract: “Motor vehicle-related child hyperthermia fatalities (MVRCHF) have risen slightly in the past decade, but little research has been done investigating the circumstances surrounding MVRCHF. In order to address gaps in our understanding, the current study describes MVRCHF circumstances among children <1–14 years of age in the United States from 1999 to 2007. Three sources were used to identify child hyperthermia death cases in the United States from 1999 to 2007: the Centers for Disease Control and Prevention’s Compressed Mortality File (1999–2004), the Golden Gate Weather Service’s public MVRCHF database (2003-Present), and an independent internet search. Data about the victim’s characteristics and the circumstances surrounding the death were extracted. From 1999 to 2007, 231 MVRCHF were identified. Children were left unattended in >80 percent of cases, 25 percent of victims were playing at the time of death, and 60 percent were male. On average, the core body temperature was 107.2 degrees F after being left inside the vehicle for an average of 4.6 hours. The largest number of deaths occurred in the South, followed by the West, Midwest, and Northeast. Parents were found to be accountable for 2/3 of the hyperthermia deaths. The geographic distribution of incidence may be attributable to two major influences: (1) regional climate differences; and (2) population characteristics. The accountability of parents for MVRCHF is likely due to the exposure-risk concept, in which the situation/circumstances increase the injury probability.”

How automobiles contribute to heat stroke

Impact of Dangerous Microclimate Conditions within an Enclosed Vehicle on Pediatric Thermoregulation
Grundstein, Andrew; Duzinski, Sarah; Null, Jan. Theoretical and Applied Climatology, 2017.

Abstract: “Pediatric vehicular hyperthermia (PVH) persists as the leading cause of non-crash, vehicle-related deaths among U.S. children with an average of 37 children dying after being left unattended in motor vehicles each year. Our study aims to demonstrate the microclimate conditions within an enclosed vehicle that lead infants and small children to reach key physiological heat thresholds: uncompensable heating (>37 degrees C) and heatstroke (>40 degrees C) under ‘worst case’ conditions. A modified version of the Man-Environment Heat Exchange Model was used to compute the length of time for an infant to reach these thresholds. Several different scenarios were modeled using different initial cabin air temperatures. Assuming full sun exposure and maximum heating rates, an infant may reach uncompensable heating within 5 minutes and experience hyperthermia anywhere from 15 to 55 minutes depending on the starting cabin air temperature. The rapid approach of these heat-related thresholds occurs as enclosed vehicles maximize heating and minimize cooling mechanisms, leading to net heating and increase in core body temperatures. Health experts can use this information to support public health messaging on the topic of PVH by explaining why it is important to never leave a child alone in a car and increase the public perception of severity and susceptibility to this ongoing public health issue.”

Heat Stress from Enclosed Vehicles: Moderate Ambient Temperatures Cause Significant Temperature Rise in Enclosed Vehicles
McLaren, Catherine; Null, Jan; Quinn, James. Pediatrics, 2005.

Conclusions: “Even at relatively cool ambient temperatures, the temperature rise in vehicles is significant on clear, sunny days and puts infants at risk for hyperthermia. Vehicles heat up rapidly, with the majority of the temperature rise occurring within the first 15 to 30 minutes. Leaving the windows opened slightly does not significantly slow the heating process or decrease the maximum temperature attained. Increased public awareness and parental education of heat rise in motor vehicles may reduce the incidence of hyperthermia death and improve child passenger safety.”

How young bodies are impacted

Fatal Heat Stroke in Children Found in Parked Cars: Autopsy Findings
Adato, Berliz; et al. European Journal of Pediatrics, 2016.

Abstract: “A common and unfortunate cause for heat stroke-related deaths in children is entrapment in closed vehicles. The aim of this study was to analyze the pathological consequences of such grave events. Autopsy reports of all children that were brought to a national forensic medicine center after being found dead in closed vehicles over a 21-year period (1995–2015) were reviewed. Data extracted were the circumstances of the events, child age, sex, height and weight, time, date and duration of entrapment, and environmental temperatures at the time of entrapment and the autopsy findings. Eight deceased children were brought to the forensic medicine center for autopsy, and seven families consented to the procedure. Autopsy findings included diffuse petechiae and hemorrhages of serosal membranes (n = 7/7) and lung congestion (n = 3/7).”

Evaluating Infant Core Temperature Response in a Hot Car Using a Heat Balance Model
Grundstein, A.J.; et al. Forensic Science, Medicine and Pathology, 2015.

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 degrees C/hour (3.0 degrees F/hour) and from heat stroke to demise was 4.8 degrees C/hour (8.5  degrees F/hour).”

The image above was obtained from the Flickr account of Joseph Novak and is being used under a Creative Commons license. No changes were made.

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