Heat Danger In Cars: Not Just A Summer Problem. (cover story)

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Author: Unknown

Most parents and child-care providers are aware that the summer sun can create an extremely hot environment inside a car. It's been shown that when the outside temperature is above 86°F, the temperature inside a vehicle quickly reaches 134-154°F. Even though it's well known that it's dangerous under these conditions to leave infants or children in cars with the windows rolled up, there have been increasing reports of children dying from heat stroke after being left unattended in motor vehicles.

But is there also a risk on cooler days? And can leaving the Windows open "a crack" keep the temperature under control? To answer these questions, researchers from California measured the temperature rise over an hour in a dark sedan on different clear sunny days with outside temperatures ranging from 72-96°F. On two of these days, they also measured the temperature rise with the windows opened 1.5 inches.

They found that whatever the outside temperature, the rate at which the temperature increased inside the car was pretty much the same, and 80% of the increase occurred in the first half hour. The researchers weren't surprised to find that when the outside temperature was 96°F, the inside temperature rose roughly an additional 40°. However, they also found that even at the coolest outside temperature, temperatures inside the car reached 117°F. On average, for outside temperatures ranging from 72 to 96°F, the temperature inside the car rose by about 40°F. The authors also found that "cracking" the windows did not affect the final maximum temperature inside the vehicle.

The authors point out that although the problem of heat stroke in children is hardly one of the top 3 causes of unintentional death (those are motor vehicle accidents, drownings, and burns), heat illness may be easier to prevent if caregivers are made aware of the danger. "It is worth considering incorporating this message along with a discussion of the importance of car seats as part of child passenger safety education for caregivers." (McLaren C et al: Pediatrics, July, 2005, electronic edition, pages e109-e112)

COMMENT: Infants and young children particularly are vulnerable to heat stress, and this study provides important new information that can make a lifesaving difference to the health of a child. Parents and other caregivers need to understand that the heat gain in a vehicle on even relatively cool sunny days, with or without the windows "cracked", is far greater than we may think. As a rule of thumb, it might be useful to remember the figure offered by the authors--that when the outside temperature is between 72-96°F on a sunny day, the temperature inside a car will be about 40° higher. The authors didn't test outside temperatures below 72°, but we would, to be on the safe side, apply the "add 40" rule to those cooler temperatures, as well.