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It's a deadly trend that sweeps the nation each summer as the weather heats up: children die after being left in hot cars.

Whether forgotten by an over-stressed parent or left for "just a minute" while a caregiver makes a quick trip into a store, an average of 38 children die each year after suffering hyperthermia or other heat-related illnesses when abandoned in hot cars, according to the Kansas-based Kids and Cars, an organization dedicated to preventing child deaths in vehicles.

The case of Cooper Harris, a toddler who died in Georgia in June after being left in a hot car, has again brought the issue to light. So far this summer, 15 children across the U.S. have died after being left in hot cars.

Utah has seen a handful of cases in the past decade, including a horrific 1998 incident in West Valley City where two sets of sisters and their friend died in the trunk of a vehicle as outside temperatures hovered around 100 degrees.

The parents in these tragic cases come from every social class. While it's easy to say "this could never happen to me," hundreds of caregivers through the years have found themselves making a mistake they never thought possible. Something as minor as a change in routine can leave a responsible parent forgetting to take a sleeping child out of the car.

That can spell trouble quickly for children, whose body temperatures warm faster than an adult's, said Kerry Whittemore, M.D., a pediatrician at the University of Utah's South Jordan Health Center.

"Young children have a higher surface to mass ratio than adults, meaning they absorb heat faster than adults do," said Whittemore. "You cool off by sweating and children produce less sweat than adults and start sweating at a higher body temperature than adults. They also have a lower absolute blood volume so less heat can be dissipated by bringing blood to the surface (where heat can be released to the environment)."

Whittemore noted that small children locked in car seats usually can't free themselves from the restraints to leave the vehicle when it gets too hot, leaving them prone to suffer serious heat related injury when their critical thermal maximum (CTM) is exceeded.

The CTM is defined as the degree of elevated body temperature and duration of heat exposure that can be tolerated before cell damage occurs. Human thermal maximum is estimated as a core body temperature of 42ºC (107.6ºF), lasting between 45 minutes and eight hours.

Reaching a CTM happens quickly to young children in hot cars, according to Jan Null, a meteorologist and adjunct professor at San Francisco State University who studies the trend of hyperthermia deaths of children in vehicles.

Hyperthermia — a condition caused by extreme overheating to the body — can occur quickly. A vehicle's interior temperature rapidly rises once left outside, according to Null, who operates the web site After 10 minutes, the inside temperature of a vehicle on average rises 19 degrees. After 30 minutes, the vehicle is 34 degrees hotter.

That rapid rise in temperature is why parents should think twice before leaving their child for a short time in a vehicle, said Whittemore.

"'How long is too long?' is a question dependent on a number of factors, including the age of the child, how the child is dressed, the temperature of the car when the child is left, the outside temperature, and whether a car has been left in the sun or shade," she said. "Is a child going to die from literally being left in a car for one minute or even five minutes? No. Is it worth the risk? I'd say no to that as well."

For parents who have left their child in a situation of prolonged heat, it's best to monitor children for warning signs of heat stroke. A big red flag is a child's elevated core body temperature. If a thermometer says the child is running a temperature of more than 104 degrees, it's wise to seek medical attention, said Whittemore.

Other worrisome behavior, such as mental status changes — excessively sleepy or even passing out, inappropriate behavior, flushed skin, or even seizures in some cases — are symptoms that should be brought to the attention of a medical provider, she said.

"Heat stroke is treated number one by removing the child from the high temperature location and cooling them off. This is done with removing the clothes, placing ice packs on the face, groin, arm pits, and lots of cool fluids while on your way to seeking medical attention," said Whittemore.

Melinda Rogers is a communications specialist at University of Utah Health Care. She can be reached at or on Twitter: @mrogers_utah. Safety Tips from the National Safety Council

• Never leave a child alone in a car.

• When you have children in the car, use reminders to ensure that you'll check for them when you get out of the car. For example, leave something you need in the back, such as your purse, briefcase or phone.

• Always lock your car doors after you get out of the vehicle. This will prevent children from getting into the car on their own and possibly getting trapped inside.

• If you see a child alone in a car, call 911 immediately.