Dominguez Channel Odor Event


The South Coast Air Quality Management District (South Coast AQMD) conducted an investigation into odors from the Dominguez Channel beginning in October 2021. The agency responded to over 4,700 odor complaints from residents in Carson, as well Gardena, Long Beach, Redondo Beach, Torrance and Wilmington and other parts of L.A. County. A map showing general areas where complaints were recorded can be found here.

Air monitoring efforts in the impacted areas included a variety of technologies and strategies such as handheld monitors that provided instant readings at specific locations, grab samples for laboratory analysis, mobile monitoring to assess which areas were the most impacted by this odor event, and more than a dozen fixed air monitors at specific locations throughout the community.

Overall, results showed elevated levels of hydrogen sulfide (H2S) that can cause strong odors and be a public nuisance. H2S is a colorless and odorous gas that smells like rotten eggs. Most individuals can smell the odor at very low levels, and some may generally experience symptoms such as headaches and nausea. People experiencing symptoms are encouraged to contact their health care providers.

Notices of Violation

As a result of the investigation, on December 2, 2021, South Coast AQMD issued five Notices of Violation (NOVs) to Virgin Scent, Inc. dba Art Naturals, Day to Day Imports, Inc., Liberty Properties Limited Partnership and its parent company, Prologis, Inc., and the County of Los Angeles. 

In September 2021, two companies – Virgin Scent, Inc. dba ArtNaturals and Day to Day Imports, Inc.  – stored large quantities of wellness/beauty products at a warehouse located at 16325 S. Avalon Blvd. in Carson. The warehouse is owned by Liberty Properties Limited Partnership and its parent company, Prologis, Inc. On September 30th, a large fire started on the warehouse property, and efforts to extinguish the fire continued over multiple days. Subsequently, chemicals contained in the stored products, including ethanol, passed through the storm drain system into the local flood control waterway, the Dominguez Channel. This was followed by the anaerobic decay of organic materials in the channel, which caused elevated levels of Hydrogen Sulfide (H2S) to be emitted into the air. 

On October 3, 2021, South Coast AQMD began receiving odor complaints, though the cause of the odors was initially unclear. The number of odor complaints kept rising and by October 6 was exceeding 100 complaints each day, with an incident high of over 580 complaints received on October 11. Inspectors responded to the complaints and traced H2S-type odors to the Dominguez Channel. The County of Los Angeles is the Responsible Party charged with maintaining the waterway.  

The NOVs allege that the foul-smelling H2S emissions from the Dominguez Channel caused a public nuisance in violation of the agency’s Rule 402 and California Health & Safety Code Section 41700.  At one point, H2S levels hit almost 7,000 parts per billion—about 230 times higher than the state nuisance standard. South Coast AQMD inspectors conducted 24-hour field operations during that time to ensure the safety of nearby communities. Additionally, the Los Angeles County Department of Public Works took a series of steps to address the odors, such as spraying an odor neutralizer into the channel to stop H2S emissions and using aeration devices to oxygenate the water and halt the anaerobic decay process. H2S levels declined noticeably after mitigation measures were employed.

NOVs can result in civil penalties. In some cases, the company or entity can choose to implement voluntary measures to reduce emissions or otherwise prevent further violations. If no settlement is reached, a civil lawsuit may ultimately be filed in superior court. 

Ongoing Efforts

During the incident, South Coast AQMD worked closely with an interagency group that included the U.S. Environmental Protection Agency, the Los Angeles Regional Water Quality Control Board, the Los Angeles County Department of Public Works, and various other agencies. The Los Angeles County Department of Public Health (LADPH) provided regular input regarding potential health impacts; and field operations were conducted jointly with the Los Angeles County Fire Department Health & Hazardous Materials Division (Hazmat) focusing on the protection of local schools.

South Coast AQMD continues to share data with our partners at LADPH to assist with their ongoing health guidance and assessments, as well as other agencies that are currently evaluating and investigating the incident. Coordination with Hazmat also continues in order to address occasional odor complaints and related concerns raised by members of the affected communities.

The public can continue to report odors and other air quality concerns to South Coast AQMD at 1-800-CUT-SMOG (1-800-288-7664) or through the On-line Complaint System

More information on the response to this incident can be found on the L.A. County Office of Emergency Management webpage.

Handheld Monitoring (Jerome Analyzer)

The handheld monitor is a portable air monitor that can take measurements for hydrogen sulfide (H2S) in just seconds. These types of instant results provide inspectors and air monitoring technicians an opportunity to identify potential “hot spot” areas. In addition, seven instant (grab) samples were collected for laboratory analysis for H2S and other pollutants (see lab reports below).

The maps below show H2S levels found at various locations and times during the day. Elevated levels of H2S were found along the Dominguez Channel but fluctuated throughout the day. High levels found using handheld devices provide quick information and help guide the investigation. Levels of H2S can fluctuate based on weather patterns, wind and time of day. 


10/06/21 Lab Report

10/08/21 Lab Report Sample 1

10/08/21 Lab Report Sample 2

10/08/21 Lab Report Sample 3

10/08/21 Lab Report Sample 4

Community Mobile Monitoring

On October 10 through 14, 2021, mobile monitoring was conducted between 6:30 a.m. and 5:30 p.m. near the Dominguez Channel and in and around surrounding communities where odor complaints had been received. Overall, mobile monitoring showed elevated levels of H2S with the highest levels along the Dominguez Channel. Results also showed some elevated levels in Carson communities and areas adjacent to the Dominguez Channel.

On November 6 and 8, 2021, mobile monitoring was conducted between the hours of 11:30-5:30 p.m. near the Dominguez Channel and in surrounding communities. Some elevated levels were found in locations near the channel; however, overall levels of H2S showed drastic improvement from original data collected in October.

Please note that the below maps show a snapshot in time, with levels often changing in an instant based on weather and wind patterns.

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Mobile Monitoring maps for specific days can be found below:

November 6-8, 2021

October 10, 2021

October 11, 2021

October 12, 2021

October 14, 2021

Volatile Organic Compounds (VOCs) and Air Toxic Pollutants

South Coast AQMD also conducted monitoring and sampling for VOCs and other air toxics. The data showed no elevated levels of VOCs or other air toxic pollutants (e.g., benzene) that would be typically associated with direct petroleum emission sources such as oil pipes or refineries.

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10/8/21 Lab Sample 1

10/8/21 Lab Sample 2

10/8/21 Lab Sample 3

Rule 1180 Fenceline and Community Air Monitoring

South Coast AQMD also has 12 fixed air monitors located throughout the community as part of its Rule 1180 Refinery Fenceline and Community Air Monitoring Program (see map below). These air monitors provide continuous, real-time measurements of H2S, VOCs, and other air pollutants 24-hours a day. Community members can sign up to receive automatic email notifications if air pollution levels reach elevated levels. Click here to sign up for email notifications.  

To view near real-time data from this robust air monitoring system, as well as past data, please visit the air monitoring page.

A temporary monitor was placed near E. 213th street and the Dominguez Channel to provide additional data on this odor event and to evaluate potential impacts on communities near the waterway. The temporary monitor (213th & Chico) took continuous, real-time measurements of H2S from October 14, 2021 to January 28, 2022.

H2S 1-hour Data: All H2S data displayed in this Table is preliminary and is subject to final quality assurance and validation. Data listed is the 1-hour average for that day and time. N/A means that data at a specific location and date/time is not available due to a variety of reasons such as loss of communication, equipment malfunction, instrument maintenance, etc.

Slide 10(Note: The arrows on the icons for each stationary monitor indicate wind direction.)

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