A strong natural gas odor hung over Belmont Shore on Friday morning, prompting a few concerned residents to call the Long Beach Fire Department. By the afternoon, the source of the stench still hadn’t been identified, officials said.

These passing odors aren’t a new phenomenon by any means. In fact, the Long Beach Fire Department receives both calls for service and calls from media about them “frequently,” Brian Fisk, a spokesman for LBFD, told the Post.

The smell was first reported to the Fire Department at 10:10 a.m. Shortly after, two other calls came in, but firefighters were unable to locate the source.

Lee Peterson, a spokesman for the Port of Long Beach, told the Post that he hadn’t received any reports about the smell. Bob Dowell, director of the city’s Energy Resources, confirmed the smell wasn’t coming from any of the four THUMS oil islands.

“We have alarms, we have everything. If there was something that got over-pressured and vented the atmosphere, we would have known about it,” he said. “I called and they checked all their operations today. We’ve had no releases of any type.”

According to Dowell, this is a phenomenon that has beguiled Long Beach agencies for years.

“It’s a very mystifying thing,” he told the Post. “We just know for a fact that it doesn’t come from our [oil] islands, but that doesn’t mean that we know where it comes from.”

Often, by the time the South Coast Air Quality Management District is called out, “it’s gone, it’s moved on,” Dowell said.

SCAQMD did not immediately respond to a request for comment.

From the ports to the refineries in Wilmington and Carson to oil tankers off the coast—fingers have been pointed in many different directions over the years as periodic mystery odors wafted from areas in Huntington Beach to Downtown Long Beach.

“Many times it starts down in Huntington Beach and works its way up through Seal Beach, then it works its way into the Belmont Shore area,” he said. “So, if you look back through the history of this stuff, it’s been an ongoing thing.”

In the past, Dowell says tankers anchoring in the harbor are the source of “a lot of odors,” especially when tankers engage in “off-gassing.”

“I’m not going to say that that was them, but many times, what we have found is that when we have a pretty high number of tankers out there and it gets warm … their tanks will just vent up to the atmosphere, and when they do, those things can be pretty much the source of everything,” he said.

In 2018, the South Coast Air Quality Management District cited a 2 million-barrel crude oil tanker, Nave Photon, off the coast of Long Beach in connection with pungent odors that hung around coastal communities.

But more often than not, Dowell says officials aren’t able to identify the source before it leaves the area. In the seven and a half years he’s worked with Energy Resources, he says it’s been an issue that’s consistently raised each year.

“And this is the mystery we have,” he said. “The Fire Department has a bunch of these little air catchers out there and whenever these incidents are called in, they can capture air and they analyze it. … We’ve done everything and anything that you can imagine.”

While Dowell says there have never been any reports of people falling ill or animals getting sick, it remains unclear whether these noxious odors are harmful to the communities they permeate.

“Because we don’t know what they are,” Dowell said. “I can tell you that if it’s methane. … Methane itself isn’t harmful in and of itself, but we haven’t been able to identify that it’s even methane—it could be any number of things that are out there.”

Dowell said the city and surrounding municipalities are still trying to crack the case.

“We would one day love to identify it,” he said. “There’s a whole consortium of folks from Huntington Beach to Seal Beach to Long Beach that work whenever these things occur and they scramble to try to go out and figure out what causes these things. They’ve been doing it for years, and have yet to ever identify the absolute known source of it.”