Oct. 03–More than 400 complaints about a rotten-egg smell poured into the Air Quality Management District from Sept. 28 to Oct. 1, with most calls coming from a stretch of coast from Newport Beach to Redondo Beach. .
The mysterious odor has intermittently plagued the coast for years, with AQMD doggedly investigating its origin. The agency has yet to definitively identify the source, although air samples indicate it may be related to offshore petroleum rigs or tankers.
Experts says it’s unlikely to pose a long-term health risk, but it continues to annoy residents and visitors with no end in sight.
“It’s a documented problem,” said Joseph Lyou, president of the Coalition for Clean Air and an AQMD board member. “This odor has been very frustrating for AQMD.”
What is the smell?
It’s most likely hydrogen sulfide, which has a pungent sulfur odor and is added to natural gas and other odorless toxins to help quickly identify potentially dangerous leaks.
But it is also found in oil fields and other petroleum operations, and can arise from rotting organic matter such as seaweed, algae blooms and dead fish.
What’s known about the source of the most recent stink?
AQMD is investigating whether part of the problem stems from a leak of sulfur hexafluoride Sunday at an Edison substation in Huntington Harbour.
The chemical is often used in high-voltage electrical equipment. Because it’s odorless, hydrogen sulfide may be added so leaks can be more easily detected.
A report filed with the state shows that 5 pounds of the compound leaked from the substation.
But because the recent flood of complaints started before the leak, AQMD is looking for other sources as well. Since the odors typically occur near the coast while winds are blowing from the ocean toward land, the primary source or sources are thought to be offshore.
Could it be methane, a.k.a. natural gas?
The Huntington Beach Fire Department wrote on its Facebook page that the source was a naturally occurring “methane plume” from the ocean. But methane in its natural state has no odor and is not among chief culprits being considered by AQMD.
Why do experts think it may be related to petroleum operations?
AQMD regularly tests the air during odoriferous episodes and “some compounds have had a petroleum signature,” said AQMD spokesman Sam Atwood.
Has AQMD targeted petroleum operations in its investigations?
Yes. AQMD has tested the oil rigs offshore of Long Beach and found that they complied with all regulations, Atwood said.
The agency also uses infrared cameras to determine if significant levels of emissions coming from refineries, oil tankers and petroleum-loading terminals.
If there’s a leak, how big might it be?
Not necessarily very big.
“These odors are detected at very low levels,” Ed Avol, a USC professor of environmental health. “That’s why they’re put in methane. You can smell it almost before you can measure it.”
What is the health risk?
“At higher concentrations, (hydrogen sulfide) can create a health hazard,” Avol said.
There is no indication that the compound is at those concentration levels.
Nine months of AQMD testing in 2017 found that levels were below those at which short-term headaches and nausea can occur in some people. Hydrocarbons sometimes occurred in levels higher than “typical” but below thresholds the state has determined are likely to cause health problems, according to the AQMD website.
“We don’t think this poses any long-term health issues,” Atwood said. “As with any odor issue, there can be short-term effects. And there’s a quality of life issue.”
What should people do if they detect the rotten-egg smell?
“They should definitely call us and let us know at 800-CUT-SMOG,” Atwood said. “It’s important they call us immediately when we smell it, not days later.”
If side effects are felt — or if someone simply wants to get away from the annoying smell — they can go inside, close the windows and turn on the air conditioner, he said.
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