Información en español
Recent & Upcoming Activity
Health Risk Assessment and Risk Reduction Documents:
Amended Early Action Reduction Plan:
Overview
South Coast AQMD has an ongoing investigation into emissions of EtO from facilities within our jurisdiction. For more information on the overall initiative please visit: www.aqmd.gov/eto.
Sterigenics conducts sterilization of medical equipment using a gas called Ethylene Oxide (EtO) and operates in Vernon within two buildings between 49th St. and 50th St. on Gifford Ave in an industrial area. The nearest residential area is about 500 feet away, and the nearest school is 1700 feet away.
Based on sampling around the facilities, high levels of EtO have been discovered, and South Coast AQMD is taking several actions to identify emission sources and reduce emissions as quickly as possible including:
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Air monitoring efforts at the facilities and near the surrounding community.
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Proposition 65 Notice
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A complete investigation into the facilities’ equipment and compliance with South Coast AQMD rules, regulations and permit requirements.
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Evaluation of immediate actions to be taken by the facilities to reduce leaks or fugitive emissions, including leak and source testing.
More Information
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For more information, please contact the South Coast AQMD Public Advisor at publicadvisor@aqmd.gov.
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To receive notifications related to the Sterigenics Vernon facilities, please fill out the form at www.aqmd.gov/sign-up.
Comments from Local Officials & Community Groups
Response Letters to Local Officials & Community Groups
South Coast AQMD has provided informational letters to local officials to address concerns regarding Sterigenics:
Ongoing Investigation
During a visit to the Sterigenics buildings in Vernon on March 31, 2022, South Coast AQMD detected odors near various equipment. Initial air samples were taken directly outside the facilities, and results showed elevated levels of EtO, prompting more comprehensive air monitoring and further investigation.
South Coast AQMD is working with the operator on immediate and near-term actions. A source test was required and has been conducted on the wet scrubber at the 50th Street building, a team of South Coast AQMD engineers and inspectors conducted an assessment to identify potential emission sources that are contributing to the elevated levels, and to identify measures to further reduce EtO emissions.
South Coast AQMD inspectors issued a Notice of Violation to the Sterigenics 50th Street building on May 5, 2022 for failure to operate the air pollution control system in accordance with the facility’s permit; for failure to maintain the air pollution control system in good operating condition; and for failure to equip control equipment with a pressure gauge and a pH meter, both of which were required in the permit. Inspectors also issued Notices to Comply requiring the facility to provide operating records.
On June 30, 2022, additional Notices of Violation were issued to Sterigenics for installing control equipment at both buildings without first obtaining air quality permits. For the 50th Street facility, during an on-site visit on June 17, 2022, inspectors also observed equipment operating in violation of permit conditions.
On March 7, 2024, South Coast AQMD was notified by Sterigenics that the facility exceeded the lower trigger value threshold of 10 ppb under the Early Action Reduction Plan (EARP). The facility was required to curtail operations by 20% within 24 hours of receiving the exceedance notification and conduct additional air monitoring. Curtailment ended on March 14, 2024.
On August 2, 2024, following a review of historical data obtained from Sterigenics, Notices of Violation were issued to the 49th Street and 50th Street facilities for operating air pollution control equipment contrary to permit conditions by failing to maintain minimum scrubbing solution flow rates on multiple dates in 2022 and 2023. These were technical violations of facility permits and not the result of any fugitive emissions. Additionally, on August 6, 2024, a Notice of Violation was issued to the 49th Street facility for the failure to conduct an asbestos survey prior to renovation activities that took place at the site in January 2023.
South Coast AQMD continues to conduct a full investigation and evaluation of all equipment to ensure that the Vernon facilities are adhering to permit conditions, meeting rule requirements, complying with the EARP, and using proper air pollution controls.
Notices of Violation:
AB 2588 Air Toxic “Hot Spots” program
On June 7, 2022, the Sterigenics facility (49th and 50th Street buildings) was designated as a Potentially High Risk Level Facility. A facility is designated a Potentially High Risk Level Facility when emissions data show either a potential to exceed or that emissions have already exceeded cancer risk thresholds (greater than 100 chances in a million). As a Potentially High Risk Level Facility, Sterigenics was required to develop an Early Action Reduction Plan that includes measures that can be taken immediately to reduce health risks. In addition, the facility was required to submit an Air Toxics Inventory Report (ATIR), conduct a Health Risk Assessment (HRA), and submit a Risk Reduction Plan (RRP). As of early December 2022, these documents have all been submitted by the facility, and are under various stages of review and approval.
South Coast AQMD staff identified deficiencies and rejected the ATIR on December 2, 2022. Sterigenics did not submit a revised ATIR, therefore South Coast AQMD modified the ATIR to fix the deficiencies and approved it on May 26, 2023. Staff also identified deficiencies with the HRA and rejected it on October 31, 2023. A revised HRA was received on August 15, 2023 which did not address all of the deficiencies. Staff modified the HRA and approved it as modified on June 6, 2024. The results of the HRA exceeded the Rule 1402 notification and risk reduction thresholds. A public notification meeting is scheduled for August 7, 2024. A revised RRP was received on July 12, 2024, and is currently under review by staff.
Amended Early Action Reduction Plan
Curtailment
The approved Amended Early Action Reduction Plan set a temporary threshold for EtO emissions from the facility of 10 parts per billion (ppb) over a 24-hour period (see below). This temporary threshold ensures that the facility does not reverse any emission reductions that have been achieved recently while more permanent engineering controls are put into place. If air monitoring results near the facility show one EtO value at 10 ppb or higher, the facility must initiate curtailment of its operations. Repeated exceedances of the threshold within a rolling 15-day period may result in a temporary shutdown of the facility.
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EtO Level ≥ 10 ppb
but <16 ppb
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Action
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EtO Level ≥ 16 ppb
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Action
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First Sample
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20% Curtailment of Operations
(maximum 800 lbs of EtO usage per day)
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First Sample
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40% Curtailment of Operations
(maximum 600 lbs of EtO usage per day)
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Second Sample
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40% Curtailment of Operations
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Second Sample
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80% Curtailment of Operation
(maximum 200 lbs of EtO usage per day)
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Third Sample
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60% Curtailment of Operations
(maximum 400 lbs of EtO usage per day)
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Third Sample
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100% Curtailment of Operations
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Fourth Sample
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80% Curtailment of Operations
(maximum 200 lbs of EtO usage per day)
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Fifth Sample
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100% Curtailment of Operations
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Curtailment begins after South Coast AQMD is notified of an exceedance of the threshold. Laboratory analysis can take many days to complete. Sterigenics must provide results for sites M1, M2, M3 and M5 (see figure 5 below) within 10 days of collecting the sample. Sterigenics must also provide sample data within three hours of receiving results from their laboratory analysis when levels are above curtailment thresholds.
Sterigenics may resume normal operations once data from the same monitor that triggered the curtailment shows EtO levels are below the thresholds set under the plan.
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Sterigenics Vernon Curtailment
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EtO Sample Level That Required Curtailment
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Curtailment Sample Date
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Monitor Location
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Action
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Curtailment
Start Date*
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EtO Sample to End Curtailment
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Date of Sample
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Curtailment
End Date
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20 ppb
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2/23/23
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Sterigenics Monitor M1
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20% Curtailment of Operations
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3/4/23
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1.8 ppb
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3/1/23
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3/7/23
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13 ppb
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3/1/24
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Sterigenics Monitor M5
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20% Curtailment of Operations
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3/8/24
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1.8 ppb
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3/7/24
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3/14/24
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Air Monitoring Efforts
From April 2022 through April 2024, South Coast AQMD conducted local air sampling to determine levels of EtO in the surrounding community and evaluate potential sources of emissions coming from the Sterigenics facilities. Early in this investigation, individual grab samples (an air sample collected at one location at one point in time) were taken near the facilities (Figure 1). Grab samples were also collected near the surrounding community and the closest school (Figure 2).
Additionally, mobile monitoring was conducted to collect data on volatile organic compounds (VOCs) around the facilities and the surrounding community. VOC signals associated with EtO were elevated near the facilities; however, levels in the community were within typical background levels.
As a result of these survey activities, air samplers were placed near Sterigenics’ facilities and in the community (Figure 3) to collect 24-hour samples (Figure 4). Sampling at Site #2 concluded on May 5, 2022; sampling at site #3 concluded on February 12, 2024; sampling at Site #4 concluded February 18, 2024; and sampling at Site #1 concluded on April 18, 2024.
South Coast AQMD worked with Sterigenics’ Vernon facility operator to identify potential sources of EtO from their operations and the facility implemented actions to reduce EtO emissions. As part of the facilities Early Action Reduction Plan, the facility installed air samplers around the facility adjacent to agency monitors and data collected was compared to ensure accuracy. The facility monitors, along with the strengthened requirements on the facility under the recently amended Rule 1405, led to South Coast AQMD concluding its sampling activities. Sterigenics is responsible for continuing to collect and analyze 24-hour samples near their Vernon facility and provide that data to South Coast AQMD. The agency will occasionally collect 24-hour samples at one or more of these locations for quality assurance and quality control purposes.
Grab Samples
Figure 1. Map of grab samples. Concentrations are in parts per billion volume (ppbv).
Community Grab Samples
Figure 2. Map of community grab samples. Concentrations are in parts per billion volume (ppbv).
24-Hour Integrated Sample Locations
Figure 3. Map of 24-hour sampling locations.
This plot is interactive, individual data points can be viewed with a mouse hover. The view can be reset by selecting the circular arrows to the right of the plot.
Figure 4. 24-hour samples - South Coast AQMD air monitoring data can be found here (PDF).
Facility Air Monitoring
As part of the facility’s Early Action Reduction Plan the facility has installed four air monitors around the facility (see figure 5) and provides that data to South Coast AQMD.
Data from the air monitors operated by the facility can be found here. (PDF).
Ramboll Sampling Sites
Figure 5. Map of Early Action Reduction Plan
Health Impacts
South Coast AQMD is required to use methodologies developed by OEHHA in its health risk programs. Based on preliminary monitoring data, the primary concern is off-site worker exposure. This data indicates that workers at facilities adjacent to the Sterigenics facilities could be experiencing cancer risks as high as about 750 in a million, if they are or have been exposed for long periods (i.e., a 25-year worker exposure). This risk level is more than one and a half times higher than the average lifetime cancer risk throughout the region according to South Coast AQMD’s Multiple Air Toxics Exposure Study V. The preliminary air monitoring results also show that EtO levels and off-site worker cancer risk drops off substantially (about 50 times lower) a short distance away (about 150 feet), from the facility.
South Coast AQMD issued a Proposition 65 notice on May 5, 2022 notifying the Los Angeles County Board of Supervisors, the Los Angeles County Health Officer, and the City of Vernon Director of Health and Environmental Control 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 Administration (Cal/OSHA) of potential exposure to employees at the Vernon facilities. Cal/OSHA subsequently launched its own investigation and has visited the Sterigenics facility. Additionally, South Coast AQMD is working closely with the Los Angeles County Department of Public Health and is providing data to public health officials for additional risk assessment.
Permitting
The Vernon facility consists of two buildings (49th St. and 50th St.). The 49th St. building currently has active permits for eight EtO sterilization chambers, one heated aeration room, and air pollution control equipment which includes one wet scrubber and one catalytic oxidizer. The 50th St. building currently has active permits for six EtO sterilization chambers, one ambient temperature and two heated aeration rooms, and air pollution control equipment which includes one wet scrubber and one catalytic oxidizer. Construction is in progress for the PTE/Dry Bed control system.
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/Dry Bed control system will be required to control at least 95% of EtO emissions from operations within the building. 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 has submitted four groups of applications on the following dates:
1. May 25, 2022: These applications were submitted in response to Notices of Violation (NOVs) issued for operating control equipment without first obtaining permits.
2. June 7, 2022: These applications were for the construction and installation of new control equipment and the Permanent Total Enclosures (PTEs) for both buildings. Permits to Construct were issued on January 27, 2023.
3. September 28, 2022: These applications were for the modification of exhaust piping for several existing control systems. Permits to Construct/Operate were issued on December 13, 2022
4. November 2, 2023: This most recent group of applications was submitted to finalize the construction of their PTEs for both buildings. The modifications included adding a new dry bed scrubber to each building, constructing a new heated aeration room in the 49th St. building, and modifying some of the air pollution control systems’ exhaust stacks. Permits to Construct for these applications were issued on April 30, 2024.
The facility has notified South Coast AQMD that the PTEs for both building have been constructed.
The facilities’ permits can be accessed through South Coast AQMD’s Facility Information Detail (F.I.N.D.) using the facility address or ID numbers (
126191 and
126197).
Rulemaking
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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