Hydrogen Sulfide Levels Reduced in Carson Area, but Stench Persists

Railroads and Dominguez Channel

Photo: Getty Images

CARSON (CNS) - Los Angeles County announced “drastic reductions'' today in the amount of hydrogen sulfide gas detected emanating from the Dominguez Channel, but even low concentrations of the gas is continuing to create a nuisance for nearby communities.

Thousands of residents from Carson, West Carson and portions of Gardena, Torrance, Redondo Beach, Wilmington and Long Beach have reported the noxious rotting-egg-like smell caused by organic material decaying in the channel. Many have complained of headaches, burning eyes, nausea and other discomfort.

Mark Pestrella, director of the county Department of Public Works, said the Air Quality Management District's overnight report showed “drastic reductions'' in the gas, which is at the lowest level since the incident began. However, even at low concentrations, hydrogen sulfide gas creates a smell like rotten eggs, he said.

“I was at the channel yesterday, and I confirm first hand that the odor is still very much a nuisance,'' Pestrella said during an online media briefing.

South Coast Air Quality Management District's Jason Low said about 75% of odor complaint calls have come from Carson, but officials continue to receive calls from Long Beach, Gardena, Wilmington and other neighboring cities.

More than 2,939 residents have already sought reimbursement for related expenses, Pestrella said. Reimbursements have been approved for 857 people, but Pestrella said Public Works is now notifying people within 24 hours if their desired purchases in response to the smell will be eligible for reimbursement. Twenty-six households have been placed in three hotels, and people can pick up air purifiers at Victoria Community Regional Park, 419 Martin Luther King Jr. St. in Carson.

Pestrella said the smell comes from a natural process of anaerobic digestion of vegetation that naturally releases hydrogen sulfide. To mitigate the smell, Public Works is spraying Epoleon, a natural, biodegradable spray that mitigates hydrogen sulfide odor by converting the gas into a byproduct of salt, which the county will remove in a separate process.

Crews have been spraying from overpass bridges into the channel as the tide comes in “to maximize the exposure and impact of the spray,'' Pestrella said. The goal is to have the tide move the neutralizing spray further upstream to the rest of the stream, and the county may deploy drones to spray further along the channel.

Public Works is also installing bubblers at the bottom of the channel to force air into the water and increase oxygen levels. The process will help eliminate the production of the hydrogen sulfide gas.

“To put it in simple terms, the faster we reduce the hydrogen sulfide gas concentrations, the sooner the public will be relieved from this nuisance,'' Pestrella said.

Public Works is also going to use light at night to combat the bacteria, which it believes is photosensitive, Pestrella said. Officials are also considering dredging the channel, but that would be a complicated months-long process. He said it would have to be done very carefully to prevent separate environmental problems caused by other chemicals released from the channel. If the channel needs to be dredged, it would involve draining about five acre-feet of water, equivalent to about five Rose Bowls with one-foot deep of water.

The Los Angeles County Board of Supervisors on Tuesday voted to expedite support for residents in Carson and neighboring communities suffering from the stench. Supervisors Holly Mitchell and Janice Hahn co-authored a motion calling on the Department of Public Works and county CEO to do what it takes to get relief to residents quickly, including directly distributing HEPA air filters and filtration units, handing out hotel vouchers, reimbursing cities for supplies and hiring a third party to administer relief supplies and reimbursement.

The county's Department of Public Health and the Carson City Council have declared the foul odor a “public nuisance.''

The health department on Tuesday updated its recommendations for residents impacted by the odor -- saying they should avoid prolonged outdoor activities between the hours of 9 p.m. and 8 a.m., based on patterns seen with air monitoring results, and reduce exposure whenever odors are strong.

The department also recommended keeping pets indoors and taking them to the vet if they seem lethargic, have trouble breathing or vomit.

County Health Officer Dr. Muntu Davis sought Friday to reassure community members that symptoms are expected to be temporary and reversible at the current hydrogen sulfide levels.

On Oct. 12, DPH notified residents that they would be reimbursed for reasonable expenses, including the cost of certified portable HEPA indoor air filters or temporary relocation expenses to avoid negative health impacts.

Health officials urged residents to keep their doors and windows closed to prevent the stench from entering homes, and consider replacing air filters with stronger, activated-carbon HEPA filters to help clean the indoor air.

Public health officials also urged residents with “persistent, worrisome or worsening symptoms from the odors'' to call their health care providers, especially if they have chronic health conditions.

Schools in the area were also urged to exercise discretion regarding outdoor student activities.

Copyright 2021, City News Service, Inc.

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