August 1, 2007
Heat Stress from Enclosed Vehicles
In 2007 there have been at least eighteen deaths of small children after being left inside a hot vehicle. Last year there were at least twenty-nine such fatalities in the United States due to hyperthermia after they were left in hot cars, trucks, vans and SUV's. This sadly followed forty-two child deaths in 2005. Since 1998 there have been at least a total of 323 of these needless tragedies. This study shows that these incidents can occur on days with relatively mild (i.e., ~ 70 degrees F) temperatures and can occur very rapidly.
STATISTICS
Total number of U.S. hyperthermia deaths of children left in cars, 2007: 18
Total number of U.S. hyperthermia deaths of children left in cars, 2006: 29
Total number of U.S. hyperthermia deaths of children left in cars, 1998-2007: 339
Average number of U.S. child hyperthermia fatalities per year since 1998: 36
Airbags vs. Hyperthermia Deaths
In the three-year period of 1990-1992, before airbags became popular, there were only 11 known deaths of children from hyperthermia.
In the most recent three-year period of 2004-2006, when almost all young children are now placed in back seats instead of front seats, there have been at least 110 known fatalities from hyperthermia...a ten-fold increase from the rate of the early 1990s.Important note: This in no way implies that it is advocated that children be placed in the front seat or that airbags be disabled.
Circumstances
In a recent study (Guard, A. & Gallagher, S. S. Heat-related deaths to young children in parked cars: an analysis of 171 fatalities—U.S., 1995-2002. Injury Prevention 11, 33-37) the circumstances that led to child hyperthermia fatalities were examined.
39% - child "forgotten" by caregiver
27% - child playing in unattended vehicle
20% - child intentionally left in vehicle by adult
14% - circumstances unclear
Ages
Children that have died from vehicular hyperthermia in the United States (1998-2006) have ranged in age from 7 weeks to 13 years. The average age is approximately 21 months. Below are the percentage of deaths (and the number of deaths) sorted by age.
Less than 1 year old = 32% (101)
1-year old = 21% (66)
2-years old = 22% (71)
3-years old = 12% (39)
4-years old = 5% (16)
5-years old = 3% (8)
6-years old = 2% (6)
7-years old = 1% (2)
8-years old = < 1% (1)
9-years old = 1% (2)
LEGAL ISSUES
Only 11 states have laws prohibiting leaving a child unattended in a vehicle.
Currently 15 states have proposed legislation making it a crime to leave a child unattended in a car, van, truck or SUV.
In one state it is only a crime if the child is injured or dies
The remaining 24 states do not have laws against leaving a child unattended in a vehicle. See http://ggweather.com/heat/ap_sentencing.htm for AP story about prosecution of such cases.
MEDICAL
Heatstroke occurs when the core body temperature reaches 104 degrees F.
A core body temperature of 107 degrees F is considered lethal.
Children's thermoregulatory systems are not as efficient as an adult's and their bodies warm at a rate 3 to 5 times faster than an adult’s.
VEHICLE HEATING DYNAMICS
The atmosphere and windows are relatively “transparent” to the sun’s shortwave radiation (yellow in figure below) and are warmed little. The shortwave energy does however warm objects that it strikes.
These objects (e.g., dashboard, steering wheel, childseat) heat the adjacent air by conduction and convection and also give off longwave radiation (red) which is very efficient at warming the air trapped inside a vehicle.
VEHICLE HEAT STUDY
Study of temperature rise in enclosed cars on 16 dates between May 16 and Aug. 8, 2002.
Ambient temperature were between 72 and 96 degrees F.
Dark Blue mid-side sedan with medium grey interior
Also tested with windows “cracked”
CONCLUSIONS
Average elapsed time and temperature rise
10 minutes ~ 19 deg F
20 minutes ~ 29 deg F
30 minutes ~ 34 deg F
60 minutes ~ 43 deg F
1 to 2 hours ~ 45-50 deg F
“Cracking” the windows had little effect
Vehicle interior color probably biggest factor
Parents and caregivers need to get the word out that a car is not a babysitter... but it can easily become an oven
SAFETY RECOMMENDATIONS
Do not leave a child in an unattended car, even with the windows down. Not even for a minute!
Be sure that all occupants leave the vehicle when unloading. Don't overlook sleeping babies.
Always lock your car. If a child is missing, check the car first, including the trunk. Teach your children that vehicles are never to be used as a play area.
Keep a stuffed animal in the carseat and when the child is put in the seat place the animal in the front with the driver.
Or place your purse or briefcase in the back seat as a reminder that you have your child in the car.
Make "look before you leave" a routine whenever you get out of the car.
Have a plan that your childcare provider will call you if your child does not show up for school.
Adapted from http://ggweather.com/heat/
Dept of Geosciences
San Francisco State University