THURSDAY, May 24, 2018 (HealthDay News) -- It only takes 60 minutes for a car parked in the sun to become a death trap for a 2-year-old child, a new study finds.
An hour in direct sunshine is enough to cause potentially deadly hyperthermia, said study lead author Jennifer Vanos.
And what about a car parked in the shade?
Two hours can prove fatal, said Vanos, an assistant professor in climate and human health at the University of California, San Diego.
"Some people may think that parking in shade is OK," said Vanos. "It's definitely better, but doesn't prevent death or heat injury."
The study assessed how different cars heat up on hot days over different periods of time.
In the United States, six children have died in hot cars so far this year -- and about 750 since 1998, the study authors noted.
"The circumstances usually involve a child being forgotten or a child playing unattended and locking themselves in a car," said Vanos. Those scenarios account for 54 percent and 27 percent of cases, respectively, she added.
Vanos and others believe car makers can take steps to help save young lives.
According to Dr. Gene Brewer Jr., "We need to develop better technology that is quicker and more reliable, to help alert parents and caretakers that children have been left in cars." Brewer is an associate professor of psychology at Arizona State University.
"These results are important, insofar as they illustrate just how little time an infant has after being forgotten in a car," Brewer said.
Vanos said: "The narrative of the forgotten child often involves a distracted parent or breaking a habit. Maybe the mother who usually takes the child to daycare cannot, so the father changes his normal routine before work. But the child falls asleep in the back while he drives to work and he just forgets. He comes back eight hours later and finds his child."
Such deaths have risen sharply in the wake of laws requiring passenger airbags in the front, and car seats in the backseat. "Out of sight, out of mind," said Vanos.
For the study, researchers tracked interior temperatures in six cars in Tempe, Ariz., for three days in June and July 2014. The vehicles -- two midsize sedans, two minivans and two economy cars -- were left in direct sunshine or shade.
With outside temperatures over 100 degrees Fahrenheit, sun-baked cars hit an average interior temperature of 116 degrees after one hour, the researchers observed. That figure rose to 157 degrees in the dashboard region, 127 degrees on the steering wheel and 123 degrees on seats.
Shaded-car interiors hit an average of roughly 100 degrees within an hour, rising to 118 on the dashboard, 107 on the steering wheel and 105 in seats, the findings showed.
The researchers then modeled how a 2-year-old child might fare in such conditions, given that heat stroke risk arises when body temperatures top 104 degrees.
The conclusion: One hour in a sunny spot or two hours in a shaded vehicle could cause heat injury or even death.
The research team figured an hour was the length of a typical shopping trip.
Given that "nobody in the world has an infallible memory," Vanos said, there's a push to use technology to limit risk.
Installing car sensors to alert parents that a child has been left behind is one option. Phone apps are another, she said.
"Even the most perfect of parents can make a mistake," Vanos explained. "Likely the biggest mistake someone can make is assuming that this can't happen to them."
Brewer agreed. "Almost all people who have left children in cars report the same thing: 'I never thought this would happen to me,' " he said. "There is virtually no way to know whether or not you will forget your child."
The findings were published in the May 24 issue of the journal Temperature.
There's more on children and car safety at the U.S. National Highway Traffic Safety Administration.