Read the pressure cooker instruction manual thoroughly. The manual for my model can be found here: http://www.fagoramerica.com/content/download/8799/59673/file/U40A01911.%20Rapid%20Express%20Manual%202008.pdf
You are dealing with super-heated steam inside of a pressure vessel. You and you alone are the one who is ultimately responsible for your safety and the safety of those around you. (Special Note: The manual for my pressure cooker explicitly states that the pressure cooker is not to be used on a propane burner and that it is for stovetop-use only. Your manual might provide different instructions about this and many other things, so it is important that you know how to operate the unit that you own.) I use my pressure cooker indoors, on my stovetop, because that is where I can prepare a semblance of a sterile environment.