If you are trapped under debris, most importantly cover your mouth with a handkerchief or clothing to avoid breathing in harmful substances. Do not move about too much or kick up dust. Try to tap on a pipe or wall so that others can locate you. If a whistle is available, use it. Shout only as a last resort. Shouting can lead to inhalation of dangerous amounts of dust. Most importantly, do not light a match under any circumstance. Debris usually comes with broken gas lines and thus, lighting a match could potentially spark a fire or an explosion.