"As far as we know, the odor was just here for a brief period of time, but eventually it dissipated into the atmosphere," Richmond fire Chief Michael Banks said. "Unfortunately, we couldn't find the source."
Fire crews responded to an influx of calls around 2 p.m. about a strong gas odor throughout northwest Richmond this afternoon, fire officials said.
Banks said some callers complained of headaches and breathing issues after smelling the odor, and a couple of people went to the hospital to be evaluated as a precaution.
County hazardous materials personnel and crews from PG&E checked gas lines and other sites to determine the source of the odor, but did not find one and had halted the investigations as of 4:30 p.m., according to Randy Saywer, Contra Costa County's Chief Environmental Health and Hazardous Materials Officer.
Sawyer said some organizations in northwest Richmond, including offices on Marina Way and the North Richmond Health Center, briefly evacuated voluntarily and have since returned.
The county did not order evacuations, but advised anyone concerned about the odor to shut all windows and doors to keep it from entering buildings.
Chevron, which has a refinery located in northwest Richmond, released a statement this afternoon saying that its "fenceline monitors as well as current wind direction do not indicate that there are emission sources coming from the Richmond refinery that would result in the odor."
The refinery's fire department assisted Richmond fire crews in investigating the smell, according to the statement.