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.

Based on air sampling around the facility, elevated levels of EtO have been discovered, and South Coast AQMD is taking immediate actions to identify sources within the facility and reduce emissions as quickly as possible, including:

  • Air monitoring efforts at the facility

  • Issuance of a Proposition 65 Notice (PDF)

  • A complete investigation into the facility’s equipment, processes, and compliance with air quality rules, regulations and permit requirements, and the issuance of a Notice of Violation (NOV) under South Coast AQMD rules and state law.

  • Evaluation of immediate actions to be taken by the facility to reduce EtO emissions including closing and sealing of various openings in the building.

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. Parter is  being evaluated as a Potentially High-Risk Level Facility. If potential health risk levels exceed thresholds set by South Coast AQMD, the facility is required to conduct public notification activities, and take actions to reduce their risk. As part of the AB 2588 program, the agency is evaluating the appropriate next steps for the facility, including accelerated requirements to reduce risks above threshold. If the facility is designated as a Potentially High-Risk Level Facility, they would be required to develop an Early Action Reduction Plan within no more than 90 days, and immediately implement the plan once approved. Additional risk reduction actions may also be required once the facility completes a detailed health risk assessment.

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 one air monitor at Site #3 the week of February 28, 2023, a second air monitor at site #4 on June 29, 2023 and a third monitor at site #2 on August 1, 2023. The monitor will remain at Site #1 near the facility.

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.

Propostion 65 Notice (PDF) was issued on July 28 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 is permitted for multiple EtO sterilization chambers, aeration rooms and associated air pollution control equipment. Products are loaded into sealed sterilization chambers where EtO is injected. Chambers are required to have strict requirements to capture the EtO gas and prevent 99.9% of emissions. The facility has submitted permit applications for a variety of items including a new dry bed scrubbers and administrative changes.

On September 22, 2022 South Coast AQMD approved a permit for additional dry bed scrubbers. The permits require control equipment for the dry bed scrubbers that will control at least 95% of EtO emissions from operations and the installation of a PTE that will allow the facility to maintain negative air pressure and prevent fugitive air and contaminants from escaping the building. The additional layer of controls will result in higher control efficiencies, which will be verified through Source Tests.

Once the equipment is installed and operational, tests will be performed to verify that negative pressure has been achieved in the PTE and it will be required by the permit to be monitored and maintained. Source Tests for the dry bed scrubbers are expected to take place within 180 days of issuance of the Permit to Construct to ensure proper control efficiency (recurring annually).

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 and Chlorofluorocarbon Emissions from Sterilization or Fumigation Processes reduces emissions of EtO from sterilization 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. We are working on amending Rule 1405 to strengthen requirements to address fugitive emissions, as well as provisions to further reduce EtO emissions from operations at these facilities. The rulemaking process, including Working Group meetings are ongoing and open to the public. Upcoming meeting dates can be found at the Proposed Amended Rule 1405 page.

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