DURHAM — Trays of s'mores were left to melt inside a car in front of the Museum of Life and Science on Tuesday, showing visitors that the heat in their cars can be as powerful as a campfire.

Imagine the heat that melted all that chocolate and marshmallow bearing down on your children or pets.

"Adults should never leave their children alone in a car," said Jan Parker, injury prevention specialist for Safe Kids North Carolina, a state chapter of a national nonprofit that sponsored the event.

"Even two, three minutes can be too many."

Adults sometimes leave their children in a car when they are running errands. But on a hot day - even when it's cloudy - a car works like an oven, the temperature inside rising 29 degrees in 20 minutes, Parker said. Even on an 80-degree day, the temperature inside a car can reach 109.

Children's bodies respond to heat three to five times faster than adults, and hyperthermia, or heat stroke, can strike a child in as little as 10 minutes. Sometimes a parent or caregiver doesn't want to wake a napping baby, Parker said, but brain damage can occur when body temperatures reach 104 degrees; a body temperature of 107 can be fatal.

A lowered window does not lower the heat significantly, Parker said.

Most adults leave children in cars simply because they forget, she said. On a busy day, parents can become distracted, forgetting their children are in the backseat. Parker recommended adults place their pocketbooks next to the children's car seats, or have their cellphone remind them, "Have you dropped off Kellie today?"

Heat- and water-related accidents rise as children spend more time outdoors in summer, she said.

"This time of the year is considered trauma season," she said. "We're using it as a teachable moment."

In North Carolina, it's considered child neglect to leave minors unattended in a car.

On Friday, a Durham man was arrested in Wake County and charged with leaving his 4-year-old child unattended in his car for more than 30 minutes, according to Phyllis Stephens, spokeswoman of the Wake County Sheriff's Office.

At noon Tuesday, a digital thermometer showed the temperature in the sun to be 112 degrees. The temperature inside the car with the s'mores? 179 degrees.

"I don't want to be baked like a s'more in a car," said Samuel Hasan, 8, as he bit into a dripping s'more in his hand. Samuel was visiting the museum with his siblings Matthew, 5, and Sarah, 2.

It's virtually impossible to leave her three children by themselves - in or outside a car, Heather Hasan said.

"They're pretty loud," she said.

regina.wang@newsobserver.com or 919-836-4918