In the event that the ventilation was reduced the gas could of charged the entire crawlspace area of the home. If it found an ignition source and had the right mixture the whole house could have blown up. This is an extremely dangerous situation.If you have an older home it is a good idea to have your gas pipes inspected to ensure your home is a safe place. If you smell gas make sure you shut off the main valve that supplies your home immediately and ventilate the area by opening windows or doors. Be sure to not switch on electrical switches or use anything with an open flame. Do not use any electronic devices that are not intrinsically safe ( Safe to use in an explosive atmosphere). Remember that natural gas will rise and propane will sink to the lowest point. For more info on maintaining your home, residential remodeling & custom homes visit us at www.tfgonline.com.