The smell of rotten eggs has been infecting the senses of folks living in San Francisco and Richmond since Wednesday, but air quality officials do not have a definitive answer as to what's causing the nauseating aroma.
The Bay Area Air Quality Management District said that crews are focusing on ships, landfills, wastewater treatment plants and two flaring episodes at the Chevron Richmond refinery as potential culprits.
Monitoring devices planted around the Chevron facility revealed that sulfur was released on Tuesday at some point during the initial flaring episode, officials wrote in a news release. Data pertaining to the second flaring episode is still being compiled.
"Actually, it was last night; it was a strong odor similar to eggy, egg-type odor," Charlie Hermosa, of San Francisco, said. "It was some kind of industrial smell. It definitely didn’t smell good. Perhaps it was sulfur, don’t know for sure."
For the past two nights, complaints have come, including some near the Fairmont Hotel in San Francisco, where firefighters arrived, determined it was safe, but couldn’t locate the source. PG&E also inspected the area and found no leaks.
Officials representing the Bay Area Air Quality Management District, San Francisco and the city's fire department are working to unearth the source.
"We are looking at two flaring incidents that happened in Richmond," said Kristine Roselius, of the air quality district. "We are looking at local wastewater facilities, we're looking at landfills in the area as well as ships. There are number of potential sources."
Chevron released the following statement in response to the incident.
"The Bay Area Air Quality Management District (BAAQMD) is conducting a thorough investigation on the cause of the recent odors detected in Richmond and San Francisco. Chevron is providing the BAAQMD with information to help them complete their investigation. It is premature to speculate whether our recent flaring incidents are the cause of those odors.
"The Chevron Richmond Refinery did experience some intermittent flaring activity from approximately 8:30 p.m. - 9:30 p.m. last night due to a plant upset. Chevron has met with the BAAQMD and is providing data regarding the 12/29 flaring incident to help them with their analysis. Flares are a highly regulated safety device monitored by the air district, used in refineries to relieve pressure. Chevron is committed to protecting people and the environmental in every aspect of our operations. We are working hard to assess this issue and we are supporting the BAAQMD's investigation."
For those who wish to report a strange or unusual odor, the air quality district has a hotline at 800-334-ODOR (6367).