Local air regulators are investigating a mysterious rotten-egg odor that prompted dozens of complaints from people throughout San Francisco Wednesday morning.
More than a half-dozen city and federal agencies, Pacific Gas and Electric and the city's garbage collector say they don't know what caused it.
Inspectors from the Bay Area Air Quality Management District began investigating the smell shortly after 9 a.m., said district spokesman Walter Wallace.
But, by that time people had stopped reporting the odor.
PG&E and the city's Fire Department say that shortly after 2 a.m. people began calling the utility and dispatchers, complaining of a sulfurlike smell.
PG&E received 45 calls about a gaslike odor in several different neighborhoods, according to company spokesman J.D. Guidi. Utility crews were sent out and found no gas leaks or any other problems with the company's facilities in San Francisco.
The Fire Department got more than 30 calls, according to that agency's spokesman, Jonathan Baxter. Callers described the odor as "rotten eggs or sulfur," Baxter said in an email. The calls initially came from the downtown area and then moved toward the Marina, Sunset and Richmond neighborhoods.
The U.S. Coast Guard received no reports of any fuel leaks in San Francisco Bay or off Ocean Beach Tuesday night and Wednesday morning, according to Lt. Megan Mervar, assistant chief for incident management at the agency's San Francisco sector.
The odor did not come from the city's sewer system, according to San Francisco Public Utilities Commission spokesman Charles Sheehan. "These sulfur odors are not coming from us," Sheehan said in an email.
Whatever the smell was, it didn't get anyone ill, said public health department spokeswoman Rachael Kagan.
Officials with SF Environment, San Francisco Public Works and the city's Department of Emergency Management, as well as Recology, were notified of the odor, but didn't know the cause either.