Cars left in sunshine can hit temperatures deadly to children, research warns

The study shows that if a car is parked in the sun on a hot summer day, its dashboard can hit 71C ­- high enough to fry an egg or cause third degree burns to human skin in about 60 minutes.

An hour is also about how long it can take for a young child trapped in a hot car to suffer heat injury or even die from hyperthermia, say scientists.

American researchers compared how different types of cars warm up on hot days when exposed to different amounts of shade and sunlight for different periods of time.

They also took into account how the differences would affect the body temperature of a hypothetical two-year-old child left in a vehicle on a hot day.

Professor Nancy Selover, a climatologist at Arizona State University (ASU), said: "Our study not only quantifies temperature differences inside vehicles parked in the shade and the sun, but it also makes clear that even parking a vehicle in the shade can be lethal to a small child."

Annually in the US, an average of 37 children left in hot cars die from complications of hyperthermia - when the body warms to above 104F and can't cool down.

Six children have died after being left in hot cars in the US already this year. More than 50 percent of such cases involve a parent or caregiver who forgot the child in the car, according to research.

The study used six vehicles: two identical silver mid-size sedans, two identical silver economy cars, and two identical silver minivans.

During three hot summer days with temperatures in the 100s in Tempe, Arizona, researchers moved the cars from sunlight to shade for different periods of time throughout the day.

They measured interior air temperature and surface temperatures throughout different parts of the day.

Prof Selover said: "These tests replicated what might happen during a shopping trip.

"We wanted to know what the interior of each vehicle would be like after one hour, about the amount of time it would take to get groceries.

"I knew the temperatures would be hot, but I was surprised by the surface temperatures."

For vehicles parked in the sun during the simulated shopping trip, the average cabin temperature hit 116F in one hour, according to the findings published in the journal Temperature.

Dashboards averaged 157F, steering wheels 127F, and seats 123F in one hour.

For vehicles parked in the shade, interior temperatures were closer to 100F after one hour. Dashboards averaged 118F, steering wheels 107F and seats 105F after an hour.

The different types of vehicles tested warmed up at different rates - with the economy car warming faster than the mid-size sedan and minivan.

Prof Selover said: "We've all gone back to our cars on hot days and have been barely able to touch the steering wheel.

"But, imagine what that would be like to a child trapped in a car seat. And once you introduce a person into these hot cars, they are exhaling humidity into the air.

"When there is more humidity in the air, a person can't cool down by sweating because sweat won't evaporate as quickly."

She said a person's age, weight, existing health problems and other factors, including clothing, will affect how and when heat becomes deadly.

Scientists can't predict exactly when a child will suffer a heatstroke, but most cases involve a child's core body temperature rising above 104F for an extended period.

For the study, the researchers used data to model a hypothetical two-year old boy's body temperature.

They found that a child trapped in a car in the study's conditions could reach that temperature in about an hour if a car was parked in the sun, and just under two hours if the car was parked in the shade.

Study lead author Dr Jennifer Vanos, of University of California, San Diego, said: "We hope these findings can be leveraged for the awareness and prevention of pediatric vehicular heatstroke and the creation and adoption of in-vehicle technology to alert parents of forgotten children,"

She said internal injuries can begin at temperatures below 104F, and some heatstroke survivors live with brain and organ damage.

But Dr Gene Brewer, an ASU associate professor of psychology who was not involved in the heat study, says forgetting a child in the car can happen to anyone.

Dr Brewer, who researches memory processes and has testified as an expert witness in a court case involving a parent whose child died in a hot car, said: "Often these stories involve a distracted parent."

Dr Brewer added: "Memory failures are remarkably powerful, and they happen to everyone.

"There is no difference between gender, class, personality, race or other traits.

"Functionally, there isn't much of a difference between forgetting your keys and forgetting your child in the car."