Smell of Gas Learn how to recognize the signs of a gas leak, act fast, and be prepared for an emergency. This important information is also available as a 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.