What should you do if you smell gas in a building?

When you smell gas in a building, the immediate and most critical action is to evacuate the area immediately. This response is essential because natural gas is highly flammable and can create an explosive atmosphere in the presence of a spark or flame. By getting everyone out of the building without delay, you reduce the risk of injury or fatalities that could result from an explosion or fire.

Although other options may seem reasonable, they do not address the urgent need to ensure safety first. Opening windows can help disperse gas but could also create a situation where any ignition source activates an explosion. Turning off appliances also poses risks as it may involve potential sources of sparks. Lighting a match to test the gas concentration is extremely dangerous and could ignite any accumulated gas, leading to disaster.

Therefore, evacuating immediately prioritizes life and safety, making it the correct response when detecting a gas odor.