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Don't make your parked car a Labor Day accident statistic



Ellen Griffin
SFSU Office of Public Affairs
(415) 338-6990
(415) 338-1665

Press Release published by the Office of Public Affairs


Heat still a hazard in parked autos as summer comes to a close, SFSU professor warns

SAN FRANCISCO, August 26, 2003 -- State and local police departments across the nation are preparing for Labor Day with a variety of automobile safety measures ranging from sobriety and seatbelt checkpoints to increased patrols, but parked cars can kill, too, says San Francisco State University adjunct professor of meteorology Jan Null. Null is on a campaign to stop what he calls an epidemic of heat stroke deaths when children are left in parked automobiles.

Since April 2003 in the United States, 36 children left in parked vehicles have died from hyperthermia (heat stroke), according to Null's tracking of news sources. Noting that there were no U.S. deaths from SARS and 10 from West Nile virus in the same time period, Null says "This is truly an epidemic, and the sad part is, it's totally preventable."

"You don't have to have terribly hot days to reach lethal temperature ranges," Null says. In a study of vehicle interior temperatures Null conducted between May 16 and Aug. 8, 2002, the test vehicle's temperature became potentially lethal in just 10 minutes with exterior temperature of 88 degrees F. Even with outside temperatures a low as 72 degrees, a closed-window sedan can reach a lethal internal temperature of 105 degrees in just 20 minutes.

"The message to parents is clear--that 10-minute dash into the convenience store could cost your child's life," Null says. "Just don't leave children alone in cars, in any weather," he cautions, especially infants and young children, whose thermoregulatory systems are not well developed.

In total, Null took 21 sets of temperature measurements on 15 days. The primary test vehicle was a mid-sized dark blue sedan with medium gray interior. A secondary vehicle, a white minivan with light gray interior, was used for some tests.

On average, in 16 cases with the windows fully closed, the temperature rise was 19 degrees in the first 10 minutes, 29 degrees after 20 minutes, 33 degrees after 30 minutes and 43 degrees at the one-hour mark.

"Even with the windows cracked, it takes only 10 minutes for an automobile to reach lethal temperatures of 105 on an 89 degree day," Null points out. On two occasions with the windows "cracked," the average 10 minute rise was 16 degrees, then 20 degrees after 20 minutes, 24 degrees after 30 minutes and 37 degrees at the one-hour mark.

Null hopes to conduct further studies of interior temperature on parked vehicles, to determine whether relative humidity, automobile color or other factors effect temperature gain.

Jan Null, SFSU adjunct professor of meteorology, is also a certified consulting meteorologist for Golden Gate Weather Services. He has 24 years' experience as a lead forecaster for the National Weather Service and is a certified consulting meteorologist. He can be contacted directly at: (510) 657-2246; E-mail:


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Last modified August 27, 2003, by the Office of Public Affairs