I have to mention, that alot of replies relating to the argument of leaving them in the car seem to be for convenience. Although I can understand this argument, I find it unfathomable that it is still worth the risk.

We are not only talking about heat stress, but absolute anything.... Leaving windows open invites thieves. Leaving the car running is .... well... do I need to go there?? Choking hazards.... Distress....

Sorry by I don't see he difference between this and going for a nap while the kids are home... Locking the kids in the house while you go outside to mow the lawn... Each and every excuse is a matter of convenience and hardly worth the life or risk of injury to a child.

Stepping down off my soapbox now