I was working at the table one night in my Berkeley, California, home when I smelled gas in the dining room. I checked the kitchen but didn’t smell anything, and my husband didn’t smell gas anywhere. It’s your imagination, he told me. But when our son passed through the dining room and announced he smelled gas, I called the local utility company.

That’s when things started to speed up. Not only did the utility rep take me seriously, he was shocked to find we were still in the house. Get yourself and everyone else outside the house immediately, he said, and wait for us at a neighbor’s home; we’ll be there as fast as we can. He then added something that puzzled me at the time: Don’t turn anything on or off on your way out.

When the utility truck pulled up about 20 minutes later, a grim-looking utility rep strode into the kitchen with gas detection equipment. His detector found a tiny bit of gas from the gas burners on our ancient stove, then its alarm went off: A valve behind the stove was leaking. A lot.

Our home’s open floor plan had helped the gas dissipate. In a small, air-tight room, however, the gas could have built up, and any tiny spark — even one from turning on the lights — could have triggered an explosion.

How to recognize a gas leak

You may already know that natural gas has no smell. Utility companies have added a substance to it that smells something like rotten eggs, so people will notice a gas leak.

But don’t depend on your sense of smell alone to detect a gas leak. You might have a gas leak if you notice:

  • The smell of gas
  • A roaring or hissing sound inside the house or garage (or outside it)
  • Long-lasting bubbling in standing water near the pipeline area
  • Dead grass or other dried-up vegetation in the pipeline area
  • Earth moving or dirt blowing in the air near the pipeline area
  • A damaged connection to a gas pipeline
  • An exposed gas pipeline after an earthquake or natural disaster

Related: 8 Ways to Reduce Carbon Monoxide Hazards After a Superstorm Hits

What to do if you smell gas

If you do smell gas — and especially if you smell gas and hear a hissing sound -— get out immediately (leave the doors open so the gas can dissipate). Make sure everyone in the house or building evacuates. In addition:

  • Put out your cigarette right away if you’re smoking.
  • Never use candles or matches to look for a gas leak.
  • Do not light a match, candle, stove, or lighter or turn a light switch, electrical appliance, doorbell or garage opener on or off — they could all cause a spark that would cause the gas to ignite.
  • Do not use your phone (even a cell phone) on the premises — a phone could also create a spark.
  • Call the utility emergency line only when you are a safe distance away.
  • Don’t go back into the building or area until a utility investigator has declared it is safe.

Related: Carbon Monoxide Poisoning: Is Your Family Protected?

If you’re outside and smell gas or see signs of a gas leak in or near your pipeline, flee the area before calling the utility company. Remember, a cell phone call in an area with a gas leak means a spark that might cause an explosion.

In our case, the investigator shut off all gas to the house until we had the stove valve fixed. With the prospect of cold showers and microwave meals looming ahead, I was able to find a licensed plumber to come out the next day and build a new stove valve from scratch. After the utility investigator retested the valve, he found no sign of a leak and restored gas to the property. But if we ever smell gas again, we plan to be well outside the house before making that all-important call for help.

Related: Don’t Let Your Water Heater Get You Into Hot Water

Diana is an award-winning writer and editor with more than 20 years' experience in magazine, video, book and digital journalism, with a specialty in health coverage. She was a longtime writer and news editor at the Center for Investigative Reporting; has written for publications from the Washington Post to the Times of London syndicate; and has served as a senior and/or consulting editor at Time Inc. Health, Hippocrates, HealthDay News Service and Reporting on Health. She was also editor in chief of Consumer Health Interactive, a national health and medical web site, and has reported on finance for Blueshift Research and PBS Frontline. Before joining SafeBee, she was editor of Bioenergy Connection, a national magazine about bioenergy at UC Berkeley. Her favorite safety tip: Wear a bike helmet.