Air District Blames Chevron's Richmond Refinery for S.F. Odor

Local air regulators have issued four notices of violation against Chevron for malfunctions at its Richmond refinery that sent toxic gas into the air last December, moments before residents on the other side of San Francisco Bay complained of a sulfurlike odor.

The Bay Area Air Quality Management District says it has completed its investigation into the mysterious smell in San Francisco and Richmond on Dec. 28, 2016.

The district says malfunctions at the refinery led to releases that caused a rotten egg odor to waft into the two cities, prompting dozens of complaints to dispatchers.

The agency issued the violations to the refinery on Tuesday. Two of the penalties are for releasing too much hydrogen sulfide and two are for public nuisance.

"This incident caused widespread concern throughout San Francisco and Richmond," said Jack Broadbent, the air district's chief executive officer, in a statement released Wednesday. "We will be seeking the maximum penalties available to us for this incident. In addition to being cited for this incident, Chevron will be required to make changes to their operations to ensure it doesn't happen again," .

Chevron disputes the agency's findings.

"This is a complex issue, but given the small amount of H2S (hydrogen sulfide) released, the 11-mile distance across the Bay, and the wide geography of the odor complaints, we believe it is unlikely that the flaring was the source of the odors," Chevron spokeswoman Leah Casey wrote in an email.

Weeks after the refinery malfunctions, KQED revealed that elevated concentrations of that toxic gas were detected by one of Chevron's air monitors minutes before people smelled the odor in San Francisco.

The air district says it analyzed data from air monitors near the refinery as part of its investigation.

KQED's report prompted San Francisco Supervisor Mark Farrell to call for a City Hall hearing. Farrell said that hearing would include Chevron executives and air quality experts.