If you walk into your apartment and detect a strong odor of gas, leave the building immediately and call the gas company or 911. The smell of gas -- or, more accurately, the additive added to odorless natural gas so leaks are easily detectable -- is a distinctive scent that is like the smell of the gasoline you put in your car. Most often, a faint small of gas in an apartment indicates that a stove pilot light has gone out, and the smell should dissipate within a few minutes of relighting it.
Locate the source of the odor. Start with any gas appliances such as the stove. First check the dials on the stove to make sure that all are set to "Off." If any burners are on without flame, it will produce a pronounced gas smell; turn it off and wait several minutes before proceeding.
Lift the top of your gas stove; there should be two small blue flames burning, ready to light the burners on each side. If one or both flames are out, you've likely found the source of the smell. To relight, make sure all burners are set to "Off" and light a match or long-tipped lighter and hold it to the pilot. It should relight immediately, and the smell should dissipate within minutes.
Check the oven pilot light. Pull out the broiler and look for a blue flame. If you can see the unlit pilot light, relight it with a long-tipped lighter. If you can't see it but suspect it's the oven pilot, or the pilot on another appliance such as a water heater or radiator that you don't know how to light, call your landlord right away. Once the pilot is relit, the smell should go away quickly.
Discard or deodorize any clothing or other fabric that smells of gas. The smell of gas-permeated clothing can take longer to remove, because it can transfer to other clothing. Soak all affected clothing in a solution of 1 cup of vinegar or baking soda and 1 gallon of water for eight to 12 hours. Wring out thoroughly, launder and hang out to dry in the sun.
Open windows to air out your apartment when attending to a gas smell. Once pilots are lit or all permeated fabrics are removed, it should not persist for more than an hour or so. If it does, call your landlord. If a known gas leak has been repaired by the gas company and you're still smelling gas on your upholstery and other porous surfaces, it may take a couple of days to get rid of it. Clean surfaces with a baking soda solution to get rid of the smell faster.