Parter Emissions Investigation in Carson

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Recent Updates

On August 21, 2022, Parter voluntarily shut down its EtO operations until additional air pollution controls could be implemented including modifications and upgrades to air pollution control equipment and enclosures. On September 22, 2022, South Coast AQMD approved a permit for the upgrades which included installation of additional dry bed scrubbers and completion of a Permanent Total Enclosure (PTE) for all EtO operations that are designed to capture EtO emissions, and all EtO emissions from the chambers are directed to two layers of air pollution controls.  The facility expedited construction and installation of the equipment, and a source test was conducted on November 15, 2022, which demonstrated that the air pollution control equipment is effective in capturing and reducing EtO emissions from the operation.   The air pollution control equipment has been commissioned and is in full operation.  Since the installation and operation of the new air pollution control equipment, ambient air concentrations of EtO adjacent to the facility have been at or near typical background EtO levels for the Los Angeles area.  


South Coast AQMD has an ongoing investigation into emissions of Ethylene Oxide from facilities within our jurisdiction. For more information on the overall initiative please visit:

Parter Medical Products, Inc. (Parter) conducts sterilization services for medical device manufacturers using a gas called Ethylene Oxide (EtO). The Parter facility is located in Carson with operations that run 24 hours a day, seven days a week. The nearest residential area is about 700 feet from Parter and the nearest elementary school is about 2,000 feet from Parter.

More Information

Ongoing Investigation  

South Coast AQMD has conducted multiple on-site inspections at the facility and conducted field operations in the surrounding area. On July 29, 2022, an NOV was issued to Parter for Public Nuisance in violation of agency Rule 402 and California Health & Safety Code § 41700. This violation was based on EtO emissions detected through air monitoring efforts outside of the facility.  

AB 2588 Air Toxics “Hot Spots” program

South Coast AQMD’s Rule 1402 which implements the Air Toxics "Hot Spots" program requires certain facilities with toxic emissions to prepare health risk assessments to evaluate the potential impact to the public was pre-designated as a Potentially High-Risk Level Facility. 

As a result of the pre-designation of Parter as a Potentially High-Risk Level facility, Parter voluntarily shut down its EtO operations until additional air pollution controls could be implemented including modifications and upgrades to air pollution control equipment and enclosures as detailed in the permitting section below. Since the installation and operation of the new air pollution control equipment, ambient air concentrations of EtO adjacent to the facility have been at or near typical background EtO levels for the Los Angeles area. As a result, South Coast AQMD did not designate Parter as a Potentially High-Risk Level Facility. However, Parter is currently in the AB 2588 Program and will be required to provide toxics emission inventory update at the time of their quadrennial inventory year.

Air Monitoring Efforts

In 2022, South Coast AQMD began conducting local air monitoring to determine levels of EtO near the facility and in the surrounding community. Mobile monitoring first bean on May 24, 2022, and was conducted to collect survey data on volatile organic compounds (VOCs), and signals associated with EtO were elevated near and downwind of the facility. Individual grab samples (an air sample collected at one location at one point in time) were taken next to the facility to confirm elevated ethylene oxide levels. In response, 24-hour monitors were placed adjacent to the facility and, as a precaution, they were also placed in the community and school in July of 2022. South Coast AQMD worked with Parter to identify potential sources of EtO from their operations and the facility implemented actions to significantly reduce EtO emissions. Based on the monitoring data, measurements in the nearby community and at the school have been consistent at background levels since the beginning of air monitoring efforts in July 2022. As a result, South Coast AQMD removed the air monitor at Site #3 the week of February 28, 2023, the air monitor at site #4 on June 29, 2023 and the monitor at site #2 on August 1, 2023. The monitor at Site #1 was removed November 10, 2023. 

24-Hour Integrated Sample Locations  
Parter Map

Note: This plot is interactive, individual data points can be viewed with a mouse hover. The view

South Coast AQMD air monitoring data can be found here (PDF).

Health Impacts

South Coast AQMD is required to use methodologies developed by the Office of Environmental Health Hazard Assessment (OEHHA) in its health risk programs. Air monitoring efforts for a more extensive evaluation are continuing in the community. Health impacts will be assessed when more data about the level of exposure to the community is available.

Proposition 65 Notice (PDF) was issued on July 28, 2022 notifying the City of Carson, Los Angeles County Board of Supervisors and the Los Angeles County Health Officer of the illegal discharge likely to impact public health or safety.  

South Coast AQMD has also notified the California Division of Occupational Safety and Health AdministrationLink to external website. (Cal/OSHA) of potential exposure to employees at the Parter facility. Additionally, South Coast AQMD is working closely with the Los Angeles County Department of Public HealthLink to external website. and is providing data to public health officials for additional risk assessment.


The Parter facility currently has active permits for nine EtO sterilization chambers, two EtO aeration rooms, and air pollution control equipment which includes one wet scrubber, five dry bed scrubbers, and one Permanent Total Enclosure (PTE) with negative air.  Products are loaded into sealed sterilization chambers where EtO is injected. Chambers are required to meet strict requirements to capture the EtO gas and prevent 99.9% of emissions. The PTE is required to control at least 95% of EtO emissions from operations within the facility. Additionally, it will require the facility to maintain negative air pressure to prevent fugitive EtO emissions from escaping the building. The additional layer of controls will result in higher control efficiencies, which will be verified through Source Tests. 

The facility’s permits can be accessed through South Coast AQMD’s Facility Information Detail (F.I.N.D.) system using the facility address or ID number (77129). 



EtO sterilization and aeration facilities are subject to local, state, and federal regulations. South Coast AQMD Rule 1405 (PDF) - Control of Ethylene Oxide Emissions from Sterilization and Related Operations.

During South Coast AQMD's monitoring efforts at several commercial EtO sterilization facilities, the agency became aware of fugitive emissions from sources that were not previously known. South Coast AQMD’s investigation has identified that existing pollution controls will need to be upgraded and measures will be needed to reduce fugitive emissions.

Rule 1405 was amended on December 1, 2023 to strengthen requirements for sterilization and storage facilities. The updated rule applies to 15 sterilization facilities which are required to upgrade existing or add new pollution controls and implement measures to monitor and minimize stack and fugitive emissions. Additionally, storage facilities that receive products sterilized by EtO may also be required to monitor emissions at the fenceline. More details related to Rule 1405 requirements can be found on the Rule 1405 webpage.

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