A few days ago a hurried parent forgot a toddler in a car seat in the back seat of the car and returned only half an hour later to find her dead. Just how hot can a car get with the windows rolled up?
Sunshine on Enclosed Cars Can Generate Lethal Heat in 30 MinutesThis summer much of the Northern Hemisphere is experiencing its hottest summer ever. Just four months after experiencing all-time records of winter cold, some places in the central USA experienced all-time records of summer heat. Places that just are not "supposed" to get hot are experiencing daytime temperatures of 40° C/104° F and more. And many people who are not used to the extremes of summer heat don't know that sunshine can turn enclosed automobiles into deadly ovens.
The critical factor is sunshine. On a clear day, cars can become lethally hot in even when outside temperatures are comfortable.
Pediatricians at Stanford University in California tested car temperatures on 16 clear but relatively cool days, with outside air temperatures ranging from 22° to 35° C (72° to 95° F). They found that even when the outside air temperature was 22° C/72 ° F, temperature inside a car with its windows rolled up reached 47° C/116° F in just 60 minutes. The Stanford researchers found that cracking the windows open (leaving a tiny gap for air circulation) didn't make a difference, and that even on a cool day, temperatures inside enclosed cars reached potentially lethal levels in 30 minutes.
And other studies have found that an outside air temperature of 35° C/95° F can lead to an inside air temperature of 65° C/149° F in just 15 minutes.
Infants and toddlers simply do not have enough sweat glands to keep cool and can die in minutes. Elderly people whose sympathetic nervous systems have been damaged by diabetes and people of any age who take anticholinergic drugs to control urination or salivation are also especially vulnerable to heat.
But it is people who are not at any "special risk" of heat stroke who most often die from excessive heat. The US Centers for Disease Control counted 3,442 deaths from heat in a five-year period from 1999 to 2003. Of these, 228 deaths were of infants, toddlers, and children under 15. Another 1,363 were of adults over the age of 65. But 1,816 deaths were of presumably active people aged 15 to 64, the people we are least likely to think about as risking death by sitting in an idle car with the windows rolled up.
The implication of the data is very simple. No one should stay in a parked car without ventilation, even for a few minutes. The risk of death is real. The need for rescue is immediate. Treatment for hyperthermia is 8 times more likely to save a life if it is begun with 1 hour of exposure to heat—less for the elderly and little ones. Even "healthy adults," however, can die from the heat.