Winter 2012      |      Stephen P. Sands, Registrar      |      Edmund G. Brown Jr., Governor


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Odorized Natural Gas Safety Alert

Odor fade can be a safety concern any time natural gas is flowing through pipe structures. Even experienced contractors should use caution when working around natural gas and should not rely only on sense of smell to be alerted to leaking gas. Rust, mill scale, moisture, air, cutting oil, pipe thread compound, liquids, the gas's composition and other substances in pipe can result in the loss of odorant in the gas and reduce the effect of the odorant. Odor fade also is more likely to occur in piping systems with high gas pressure or where there's little or intermittent gas flow. Certain soil conditions and fresh concrete also can strip gas of its odorant when there is an underground gas leak.

The U.S. Department of Transportation and California Public Utilities Commission provide rules and regulations for odorizing natural gas. Gas companies are required to comply with these laws, but odor fade still may occur due to the chemical and/or physical processes that cause odor fade.

As a safety precaution, utility companies remind contractors to always use gas detection devices when working with natural gas, and remember to never release the contents of a gas line into a confined space. Safely purge the contents of gas pipes and equipment to the outside atmosphere away from people, animals, structures, and sources of ignition.

Information on odor fade and natural gas safety is available on the following websites: CSLB at, Southern California Gas Company at, or San Diego Gas & Electric Company® at