Check the natural gas/LP gas system in your home. You will want to look for loose fittings, leaking valves, faulty pilot lights, and debris or improperly stored flammable materials in areas near these appliances. Check the vent stacks on gas water heaters, furnaces, and clothes dryers. Check the automatic ignition systems or pilot lights on these fixtures, as well, particularly for any guards which are not properly installed, and for lint or dust buildup in the immediate area around them. Have the gas plumbing (pipes), valves, and regulators inspected by a professional any time you smell gas or suspect a leak. Do not switch anything on if you smell gas, as it could cause fire. You can switch off anything that's one with a wooden or plastic object or stick. Open all the windows and doors so all the gas goes out safely.