By CBSLA Staff

EL SEGUNDO (CBSLA) – The Chevron Refinery in El Segundo is suspected of releasing hydrogen sulfide resulting in “odors impacting the public.” The refinery was issued a violation by the South Coast Air Quality Management District for the incident, the agency announced Thursday.

Hydrogen sulfide is a gas that occurs naturally in crude petroleum and is known to have a rotten egg smell. Short-term exposure to this type of odor can cause people to experience health symptoms such as headaches and nausea.

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On January 31, the South Coast A.Q.M.D. received more than 30 public complaints of “rotten egg- and sulfur-type odors,” the agency said in a statement.

“Inspectors confirmed that the odors were coming from the refinery,” the agency said. “Inspectors determined that the odors were caused by the release of hydrogen sulfide during the transfer of petroleum naphtha — a product of refining crude oil — to a storage tank.”

The odors had dissipated by late afternoon.

The notice of violation alleges that the refinery caused a public nuisance in violation of the A.Q.M.D.’s Rule 402 and California Health and Safety Code Section 41700.

In a statement, Chevron spokesman Jeff Wilson said the company “has been in communication with the S.C.A.Q.M.D. since the events causing the odor began. In response to the fenceline monitoring readings, Chevron actively worked to identify and eliminate the source of the odor. During that time, Chevron responded to inquiries from regulators, members of the community, and the media.”

He added, “Chevron sincerely apologizes to our neighbors for any impacts this may have caused.”

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Once issued, a notice of violation can result in civil penalties. In some cases, the company can choose to implement voluntary measures to reduce emissions or otherwise prevent further violations. If no settlement is reached, a civil lawsuit may ultimately be filed.

At the time the odors were reported, Chevron’s “fenceline” monitors showed several instances when hydrogen sulfide levels exceeded the short-term, state standard of 30 parts per billion, with the highest one-hour average being 168.7 ppb at 10:20 a.m. on Jan. 31, the agency said.

Data from the nearby community monitors in El Segundo and in Manhattan Beach showed that levels remained below 2 parts per billion during the same time period, however, the agency reported.

Staying indoors with doors and windows closed during odor events would help reduce these health impacts. Symptoms typically go away soon after the odors are no longer detected.

Chevron’s air monitoring network information can be found here, and the community air monitoring information can be found on the South Coast A.Q.M.D. website.

South Coast A.Q.M.D. is the air pollution control agency for major portions of Los Angeles, Orange, San Bernardino, and Riverside counties, including the Coachella Valley.

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(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)