Every year, dozens of children die of heat stroke after being left unattended in the car.
So, a team of researchers at Stanford University have been studying hot cars to find out how long it takes for a child left in that situation be in trouble, and they found that even a few minutes can be deadly.
On sunny days, the average temperature inside a car can jump about 40 degrees above the outside temperature within the first fifteen minutes. So, you do the math. If it's 95 degrees outside, add 40 to that for temperature climbing inside your car.
The Stanford Researchers also found cracking a window does not reduce the heat enough, and most cars reach dangerous heat levels regardless of whether a window is cracked.
This study is published in the Journal Pediatrics.