Wednesday is National Heatstroke Prevention Day -- an important reminder that as the temperature climbs in the summer, so does the danger for children left in hot vehicles.
Hot-car deaths reached a record level in the U.S. last year with at least 52 children killed, from California to Tennessee to Mississippi, according to national nonprofit KidsAndCars.org.
At least 24 children have died in hot cars in the U.S. so far this year, the nonprofit said.
Just this week, a 2-year-old boy died after he was left in a scorching hot van outside a Florida day care.
Last week, 1-year-old twins died in New York City after their father said he accidentally left them in his car all day while he was at work.
"This is my absolute worst nightmare," the twin's mother said in a statement.
The science behind hot cars
Children's bodies heat up much faster than adults do, according to the National Safety Council.
Children's internal organs begin to shut down once their core body temperature reaches 104 degrees -- and it takes very little time for a car to get too hot for children, according to a report published by the council last year.
On an 86-degree day, for example, it would take only about 10 minutes for the inside of a car to reach a dangerous 105 degrees, researchers said.
What you can do
KidsAndCars.org director Amber Rollins offers these tips for drivers:
Always keep cars locked even if you don't have children.
Always keep keys out of children's reach.
Place an item you can't start the day without in the backseat.
If a child goes missing, check the inside and trunk of all cars in the area immediately.
Teach children to honk the horn if they get stuck.
"If you see a child or animal alone in a car, do something," Rollins said. "If they are in distress, you need to get them out immediately and begin to cool them."
KidsAndCars.org is advocating for Congress to require rear occupant alarm technology in cars.
"The only thing more tragic than a child or animal dying in a hot car is knowing that there are solutions that exist that could prevent this," Janette Fennell, president of KidsAndCars.org, said in a statement on Wednesday. "By not utilizing available technology to sense a child or pet alone inside a vehicle, we are shamefully allowing this to happen over and over again."