Updated 23 October 2018

Why car heat is a child-killer

Children's bodies are especially vulnerable to the effects of heatstroke. A car interior – even for a few minutes on a mild day – can quickly become a death trap.

Every summer in South Africa, we have incidents where children's lives are lost or threatened in this way.

Why heat is a child-killer
Heatstroke occurs when body temperature exceeds 40°C and the thermoregulatory mechanism, or heat control, is overwhelmed and fails. At a core body temperature of 41.7°C, cell damage occurs and internal organs shut down. 

Children's thermoregulatory systems aren't as efficient as adults' and their body temperatures warm at a rate 3 to 5 times faster. A child's body has a greater skin surface area to mass ratio than an adult's, which means they absorb heat more quickly. Children also don't sweat as much as adults do, making them less able to lose heat through evaporative cooling.

Heatstroke as a result of exposure to high temperatures in stationary cars is known as vehicular hypothermia, and it can sometimes be fatal.

The younger the child, the greater the risk, with infants the most vulnerable of all. The majority of children and babies lost to heatstroke in cars are under seven years old, and of these, about half are under two years old. However, deaths from this cause have been recorded in adolescents as old as 14.

Cars quickly become oven-hot
Car windows act like a greenhouse: they let in sunlight and heat, trapping it inside the vehicle. Studies on temperature increases in car interiors have shown that, even on fairly mild days (outdoor temperatures in the low 20s), your vehicle can quickly become baking hot.

After only 10 minutes, the interior of a stationary vehicle can rise by over 10°C. After 1-2 hours, temperatures can increase by 28°C.

Researchers have found that leaving the window open a crack has little effect on lowering temperatures.

Although it may seem inconceivable that one could forget one's child, it has happened to some of the most caring parents. In the United States, an analysis of fatalities from vehicular hyperthermia showed that over half were as a result of children being forgotten in the back seats of cars. About 30% were as a result of children playing in unattended vehicles, and 17% were cases where caretakers had left children in cars intentionally.

Not on your watch
These safety recommendations from Jan Null, vehicular hyperthermia researcher at San Francisco State University, are lifesavers:

  • Never leave a child unattended in a vehicle, not even for a minute.
  • If you see a child unattended in a hot vehicle, call emergency services.
  • Always lock your car and ensure children don't have access to keys or remote control devices. If a child is missing, check the swimming-pool first, then the car, including the boot. 
  • Teach children that vehicles aren't a play area. 
  • Get into a "look before you leave" routine whenever you get out of the car.
  • Use visual memory aids to remind you that you have a child in the car. E.g. keep a stuffed animal toy in the child's carseat and when the child is put in the seat place the toy in the front with the driver. Or, place your purse, briefcase or laptop on the back seat.
  • Organise that your childcare provider will call you if your child doesn't show up for daycare/school.

McLaren, C, Null, J and Quinn, J. Heat Stress From Enclosed Vehicles: Moderate Ambient Temperatures Cause Significant Temperature Rise in Enclosed Vehicles. Pediatrics 2005;116;e10


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