This is one of those things I have taken for granted my kids would know. Paint me ignorant. A friend of mines home caught fire in his garage. His 13 yr old son was home alone at the time, upstairs, playing video games. Lucky enough the fire was only smoldering and wasn't giving off sufficent smoke for him to notice. When my friend and his wife got home they noticed the smoke pouring under the garage door. The fire had come to life and my friend went to raise the garage door. Thank goodness his wife new better and stopped him. The sudden rush of oxygen rich air rushing in would have been a very bad thing for anyone standing by the door as the fire would have flashed out to feed on the new fuel supply. So, I asked my kids, ages 11 and 17 what they would do if home alone and saw smoke coming under a door and the door was hot to the touch. Their reply "open it to check for fire". NO NO NO! Make sure your kids, grandkids, spouses, and loved ones no to never open the door. Get out if the house and call 911. Needless to say, my boys and I had a long talk about how not knowing what's behind a door can, in the case of fire, can save your life.