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Properties and Characteristics of Natural Gas

Color and Odor

Natural gas is nontoxic, odorless and colorless, making it difficult to detect. Gas providers add an odorant called mercaptan to the gas in their distribution lines. It smells like sulfur or rotten eggs.

Mercaptan can be a useful indicator of a natural gas leak. However, you may not be able to smell this odorant if you’ve been exposed to it for long periods of time or if other odors mask the smell. Mercaptan also may be stripped from the gas due to chemical and physical processes, in an effect known as “odor fade.”

It is also important to note that not all gas is odorized. The gas in most of Dominion Energy’s transmission lines is not odorized, for example.

So never rely on your nose alone to detect a natural gas leak. Instead, use your combustible gas indicator, (CGI), to be certain a flammable atmosphere does not exist. And be alert for other visual and auditory gas leak warning signs, including:

  • A hissing, whistling or roaring sound
  • Dirt being blown into the air from a hole in the ground
  • Continuous bubbling in water
  • A damaged connection to a gas appliance
  • An exposed pipeline after an earthquake, fire, flood or other disaster
  • A fire or explosion nearby
  • Dead or dying vegetation in an otherwise moist area over or near a gas pipeline
  • Frozen ground in warm weather