Smell of Gas Natural gas has an excellent safety record, but it's important to know when something is wrong. Learn how to recognize the signs of a gas leak, act fast, and be prepared for an emergency, by reading the information below or viewing our safety flyer. (Esta información de seguridad para el gas natural está disponible en español.) Suspect A Gas Leak? Use Your Senses See A white cloud, mist or fog, bubbles in still water, blowing dust, or dead or dying plants. Smell A distinct rotten egg-like odor. Hear Unusual hissing, roaring or whistling. If you suspect a leak, do ... Leave Immediately move to a safe location. Don't start your car, as a spark could ignite. Call 911 Don't assume someone else made the call. Report your location, including cross streets, and whether there's digging nearby. If you suspect a leak, Don't ... Smoke. Light a match. Open doors or windows. Use your landline or cell phone. Switch on/off appliances. Use a flashlight. Start a car. Attempt to make repairs.