The Aliso Canyon Disaster was a gas well blowout that occurred over the course of 4 months from October 23, 2015, to February 11, 2016, at the Aliso Canyon underground gas storage facility which is owned and operated by the Southern California Gas Company (SoCal Gas), a subsidiary of Sempra Energy. The underground gas storage facility is situated in the Aliso Canyon oil field in the Santa Susana Mountains in Los Angeles County, California, north of the Porter Ranch neighborhood of the City of Los Angeles. The blowout was the largest in United States history and released an estimated total of 109,000 metric tons of methane into the atmosphere.
As a result of the blowout, people in neighboring communities experienced "rotten egg" odors, oily mists, and acute health symptoms, including eye, nose, and throat irritation, headaches, and respiratory symptoms. The Los Angeles County Department of Public Health (Public Health) received thousands of health reports from residents in nearby communities and directed the temporary relocation of over 8,000 households and two local schools. Many residents reported ongoing health symptoms after returning home from temporary relocation and expressed concerns about potential long-term health effects.
On August 8, 2018, California Attorney General Xavier Becerra, along with the California Air Resources Board, Los Angeles City Attorney Mike Feuer, and the County of Los Angeles secured a $119.5 million settlement with SoCal Gas over the Disaster. As part of this settlement, $25 Million was secured for a long-term health study.
The Aliso Canyon Disaster Health Research Study (Health Study) will be a scientifically-based, multi-faceted and objective investigation of the potential short- and long-term health impacts of the Aliso Canyon gas well blowout and gas storage facility operations on people living in the surrounding communities.
A health study is a scientific inquiry designed to address a specific research objective related to health. Health studies can take many forms depending upon the research objective and setting. However, by definition, a health study should involve a rigorous, systematic, and objective process of exploration and measurement.
The information gleaned from health studies can be helpful in many ways. In the context of an environmental disaster, health studies can help shed light on whether exposures to chemicals or toxins from the disaster may have contributed to illness among people who were near the disaster. Health studies can also help determine if stress and emotional trauma associated with a disaster contributed to adverse physical and mental health impacts. More broadly, health studies can produce information that may be used to inform policies, programs, and other strategies to create safer environmental conditions and prevent future disasters.
On August 8, 2018, California Attorney General Xavier Becerra, along with the California Air Resources Board, Los Angeles City Attorney Mike Feuer, and the County of Los Angeles secured a $119.5 million settlement with the Southern California Gas Company over the Aliso Canyon Disaster. As part of this settlement, $25 million was secured for a study of the long-term effects of the Aliso Canyon Disaster and exposure to gas and its constituents. For more information on the settlement, please visit the Aliso Canyon Disaster Background page.
For information about The People of the State of California v. Southern California Gas Company settlement, including information relating to supplemental environmental projects (SEPs) being implemented as part of the settlement, please view the breakdown of the settlement linked here .
As part of The People of the State of California v. Southern California Gas Company's Consent Decree (Appendix D) approved by the Los Angeles Superior Court on February 25, 2019 [Full Details of the Settlement are available here ], a Community Air Monitoring Fund will be utilized to develop a real-time air monitoring network and a symptom and incident reporting system in Porter Ranch and potentially other nearby communities . This initiative is being led by the Aliso Fund Committee. The Aliso Fund Committee is composed of one representative each from the Attorney General, Los Angeles City Attorney, and the Los Angeles County Counsel. Several public meetings have been held about enhanced air monitoring networks. For more information, visit the South Coast Air Quality Management District (SCAQMD) website
Public Health's goal is to allocate as much of the settlement funding as feasible to the Health Study research contract and has therefore been providing in-kind support. Prior to the award of the research contract, the focus was on identifying health concerns and research priorities through community engagement and establishing the groundwork required to launch the Health Study. For example, settlement funds supported the development and implementation of the Community Opinion Survey which provided valuable insights on the experiences, concerns, and priorities of residents from communities near the Aliso Canyon underground gas storage facility, many of whom were directly impacted by the Aliso Canyon gas well blowout. Additionally, settlement funds supported the collection and testing of Samples of Waste Materials from the Aliso Canyon Blowout and Well-Control Attempts. Importantly, settlement funds supported the establishment of a Scientific Oversight Committee (SOC), a group of scientific subject matter experts mandated by the settlement agreement, and the SOC's development of key components of a Request for Proposals (RFP) for health research services.
Information on the allocation of Health Study funds has been shared with Community Advisory Group (CAG) and community members. For more information, follow the link provided below.
Continued CAG Meeting 18: Health Study Budget Summary Slides
After an open and competitive Request for Proposals (RFP) process, the Regents of the University of California, Los Angeles (UCLA) was selected to conduct the Health Study. UCLA met all the Minimum Mandatory Qualifications outlined in the RFP and had the highest scoring proposal. In addition to researchers from UCLA, subcontracted researchers from PSE Healthy Energy, various academic institutions and programs, and individual consultants are implementing subcomponents of the Health Study. Academic institutions and programs include New York University, University of California Davis, Oregon State University, California State University Sacramento Consensus and Collaboration Program, and Emory University School of Medicine and Clinical Biomarkers Laboratory. For more information, visit UCLA's Health Study website.
In accordance with the settlement with SoCal Gas, Public Health is responsible for:
In addition to the responsibilities outlined in the settlement, leading up to the release of the RFP, Public Health conducted extensive community outreach and gathered community feedback on the Aliso Canyon Disaster and Health Study. This feedback was instrumental to the development of the Health Study's goals and priorities and the RFP. During the implementation of the research, Public Health will continue to serve in an administrative capacity and perform contract monitoring and oversight.
The Scientific Oversight Committee (SOC) is a scientific advisory group that was mandated as part of the settlement agreement with SoCal Gas. The SOC plays a critical role in the development and advancement of the Health Study. The SOC's key responsibilities include:
Comprised of independent scientific and medical experts and public agency representatives, the SOC lends expertise in the following areas: Epidemiology, Clinical Psychology, Child and Adult Medicine, Disaster Behavioral Health, Toxicology, Community-Based Research, Exposure Assessment, Environmental Science, Air Monitoring, and Air Modeling. The SOC will oversee the implementation of the research and provide guidance to the research team throughout the length of the Health Study. At the end of the Health Study's third year, the SOC will independently analyze the Health Study's progress and determine if the Health Study should continue. Afterwards, the SOC will evaluate the Health Study's progress on an annual basis.
The communities impacted by the Aliso Canyon Disaster are the key focus of the Health Study. There are many important questions to answer about how the blowout may have affected the physical, mental, and emotional health of those residing and/or working near Aliso Canyon. Community engagement has and will take various forms throughout the planning and implementation of the Health Study, including providing input on the development of the Health Study and participating in various public events and opportunities. Prior to the award of the research contract, feedback from impacted community members, the Community Advisory Group (CAG) and other community stakeholders supported the identification of research questions, goals, and priorities for the Health Study.
During the current research implementation phase of the Health Study, UCLA is conducting all community engagement and outreach.
No. The CAG was an integral part of the process leading up to the selection of researchers, and we are now in the next phase of the Health Study. Having fulfilled its primary purpose of advising on community priorities related to research questions to be addressed by the study; informing on best practices for engaging with area communities and residents; and identifying opportunities and actions for community recovery, the CAG convened by Public Health came to a close in 2022.
UCLA's Health Study consists of five core components:
For more information on the various components of the Health Study refer to UCLA's Health Study website.
Feedback from the Scientific Oversight Committee (SOC) and the Community Advisory Group (CAG) guided the decision to solicit independent third-party research services by administering a Request for Proposals (RFP). The RFP process provided an open invitation to interested researchers and research organizations to apply for the funding opportunity, maximizing the likelihood of securing researchers with the necessary experience and expertise to implement a scientifically-based Health Study.
Interested independent third-party researchers submitted proposals by the April 12, 2022 deadline. The solicitation process was not limited to a pre-approved list of contractors. The RFP outlined specifics about the research opportunity, including Minimum Mandatory Qualifications, work requirements and funding. Proposals that were submitted by the deadline and met the Minimum Mandatory Qualifications were evaluated and scored by an evaluation committee consisting of independent, third-party scientific and medical experts based on several factors such as qualifications, experience, proposed budget, and proposed work plan.
The UCLA Health Study research team began implementing their research plans at the end of 2022.
The entire research process is expected to take 5 years contingent upon the SOC's evaluation of the Health Study's progress at the end of the third year and each following year and determination of whether the Study should continue. Additionally, there is the option to extend the research contract by five additional one-year periods. The UCLA research team anticipates disseminating findings of the various components of research beginning in 2025. For further information on UCLA's Health Study timeline, please refer to the UCLA Health Study website.
The overarching goal of the Health Study is to contribute to the understanding of the potential short- and long-term physical, mental, behavioral, social, and community health impacts of exposure to the Aliso Canyon Disaster. Specifically, the Health Study will:
The Health Study priorities include specific health, quality of life and wellbeing outcomes, populations, and exposures of concern to the community and identified by the Scientific Oversight Committee (SOC). For example, health outcomes of concern to the community include chronic health outcomes (such as cancers and respiratory conditions), as well as acute symptoms and intermediate-term outcomes (such as adverse birth outcomes).
For more information, please refer to the following document which outlines the goals and priorities: Goals and Priorities for the Aliso Canyon Disaster Health Research Study
The Health Study Goals and Priorities comprised one of several available resources for independent, third-party researchers to learn about the concerns and priorities of communities surrounding the Aliso Canyon gas storage facility. Researchers who applied for Health Study funding were required to propose study designs and research methods that were scientifically based, responsive to the RFP, and addressed the Health Study Goals and Priorities.
A wealth of feedback from community members collected during and since the Aliso Canyon blowout disaster and from the Community Advisory Group (CAG) was used by the Scientific Oversight Committee (SOC) to guide the development of the draft Goals and Priorities for the Health Study. The draft Goals and Priorities were made available for public comment on the Health Study website for 6 weeks. Members of the public submitted comments via an online feedback form or by email. In addition to providing general feedback, community members were encouraged to identify the issues that are of greatest concern and/or interest to them.
All of the feedback received was shared with the SOC to refine the Goals and Priorities and to further guide their development of the Request for Proposals (RFP) for the Health Study.
A wealth of existing data and information related to the Aliso Canyon blowout (Disaster) and gas storage facility operations exists and may be used by the independent third-party researchers to conduct the Health Study. The Health Study's Scientific Oversight Committee (SOC) believes that the wealth of existing data and information can support robust analyses to evaluate potential impacts to health, quality of life and well-being among residents of communities impacted by the Aliso Canyon Disaster.
Numerous parties - including regulatory agencies, academic institutions, and companies - have taken measurements within the facility and the surrounding communities and continue to collect relevant data and information. The existing data and information include but are not limited to hazardous materials and wastes inventory reports, sampling and analysis data, air monitoring data, and incident reports, among others.
Of note, samples have been collected directly from the gas storage reservoir and from bins that were storing soils and materials from the blowout and well-control operations. The samples were tested for an extensive array of oil and gas chemicals and the results provide information on the chemicals that were stored in the reservoir and released during the blowout and well-control attempts (results available in Sampling and Analysis Report ). Additionally, SoCalGas is required to regularly submit chemical inventories as part of the Unified Program overseen by the California Environmental Protection Agency (CalEPA). More information on this program is available on the California Environmental Reporting System website. Environmental samples that were, and continue to be, collected within the Aliso Canyon facility and surrounding communities provide information on the chemicals to which residents may have been exposed.
The Attorney General, Los Angeles City Attorney, and County all agreed to settle the litigation against the Southern California Gas Company (SoCal Gas) and resolve all disputes in the lawsuits, and therefore, the County is not going to issue a subpoena seeking information from SoCal Gas. Los Angeles County and Public Health, guided by the Health Study's Scientific Oversight Committee (SOC), will continue to compile additional information related to the blowout and operations at the Aliso Canyon gas storage facility, as needed.
To view a summary of the existing secondary data sources on potential chemical exposures and health outcomes, please visit the Historical Data page.
The UCLA Health Study research team will be collecting and analyzing additional data as part of their research study including air and natural gas samples, health survey data, clinical examination data, among others. For more information about UCLA's Health Study and its various components, please visit the UCLA Health Study website.
Please visit the Historical Data page for a summary of existing secondary data sources on potential chemical exposures, including, but not limited to, environmental reports, sampling and assessment results, and air monitoring results. The purpose of the summary is to serve as an inventory of data and information that may inform research that is being conducted as part of the Health Study. Among other pertinent information, the summary includes information on air sampling conducted within the Aliso Canyon gas storage facility and the surrounding communities spanning from the time of the blowout to the present day, and other environmental data and data sources including soil and water sampling collected within the Aliso Canyon facility and surrounding communities. Another source of information noted in the summary are hazardous materials and wastes inventories that SoCalGas is required to submit to the California Environmental Reporting System (CERS) on an annual basis.
Please visit the Health Study Research and Data page and refer to the summary of existing secondary data sources on potential chemical exposures, including, but not limited to, environmental reports, sampling and assessment results, and air monitoring results. In the summary, there is also a list of well control materials (fluids and additives) that were used during the well control operations to stop the blowout. This information can also be found in the Office of Environmental Health Hazard Assessment (OEHHA) report on Potential Chemical Hazards Associated with the Well SS-25 Well Control Materials at the Aliso Canyon Natural Gas Storage Facility Near Porter Ranch, California . In addition, in 2020, Public Health conducted extensive testing on samples that were collected from bins that were containing materials from the well blowout and well control operations. Information on this testing is also available in the summary of existing secondary data sources and the results of the testing are available on the Historical Data page.
On August 4th, 2020, Public Health worked with a third-party contractor to collect samples from waste bins containing soils and waste materials from the Aliso Canyon blowout and well-control operations (e.g., fluids, oily products, and drilling muds) that were under legal hold by the California Public Utilities Commission (CPUC). The samples were tested for an extensive array of oil and gas chemicals. The Lab Results were reviewed by the Health Study's Scientific Oversight Committee (SOC) and are publicly available on the Historical Data page.
Upon recommendation by the SOC, additional samples were collected on October 2, 2020, for potential future use by the Health Study researchers.
Thirty-one bins containing soil contaminated with Volatile Organic Compounds (VOCs) were transported to an approved treatment/disposal facility in 2016 in accordance with South Coast Air Quality Management District (SCAQMD) Rule 1166. Further information on the regulatory context for the removal and disposal of the 31 bins is provided below. Existing records and data related to the 31 bins, including VOC monitoring logs, waste characterization laboratory test results, and waste manifests are listed in the summary of existing secondary data sources on potential chemical exposures and health outcomes on the Health Study website.
More information regarding Rule 1166 can be found on the SCAQMD website.
In response to requests from residents of communities impacted by the Aliso Canyon Disaster, on November 12, 2020, the Public Health's Radiation Management team conducted radiation surveys of Aliso Canyon waste bins containing materials from the blowout and well-control operations. Radioisotope testing results can be found on the Historical Data page.
Public Health Radiation Management surveyed for the three basic types of ionizing radiation: alpha, beta, and gamma. All three types are caused by unstable atoms, which then release radioactive particles or energy to become stable. All of these types of ionizing radiation occur in nature. When analyzing radiation survey measurements, it is common to compare the measurements to background readings found in nature, which are always around us.
In summary, all test results indicate that the alpha, beta, and gamma radiation levels measured from the Aliso Canyon waste bins sampled are very low, comparable to background levels, and the low levels of radiation encountered do not pose an immediate health risk.
Following these findings, community members continued to express concern and requested further sampling within their communities. Currently, there is no indication of a problem with radiation in the communities. Nevertheless, in response to the request, Public Health's Radiation Management team secured additional resources and support to conduct community sampling and developed a draft sampling plan. Radiation Management hosted a virtual webinar on January 9 to present the draft sampling plan and address questions from residents of the northwestern neighborhoods of the San Fernando Valley. Additionally, feedback and recommendations on sampling locations were accepted from the community through January 30, 2023. The Radiation Management team used the feedback to inform the final sampling plan. Further information and updates will be posted on Public Health's Aliso Canyon Disaster website.
For further information on radiation and everyday exposure levels, please visit the Nuclear Regulatory Commission's (NRC) Doses in Our Daily Lives and Radiation and Its Health Effects.
A five-agency task force is overseeing an investigation by the Southern California Gas Company (SoCal Gas) of a spot fire that occurred in 2019 in an area of the storage field called Catch Basin 3. It was suspected that the fire may have been fueled by storage facility gas emissions. SoCal Gas released a report to the task force on the results of the investigation which concluded that the gas emittance was determined to be a result of "natural subsurface seep" and not storage facility gas. The site investigation report was provided to the Community Advisory Group (CAG) for their review and comment. SoCal Gas provided an update on these findings on their website. The report and data collected as part of the investigation is currently under review by the five-agency task force, consisting of representatives from the California Geologic Management Division, the California Public Utilities Commission, South Coast Air Quality Management District, Los Angeles County Fire Hazmat Department, Los Angeles County Department of Public Health, and California Air Resources Board.
Following the Aliso Canyon blowout, a community physician obtained data on CBC test results from a licensed clinical laboratory. A comparison of data from adults in the Porter Ranch zip code to data from adults in other zip codes indicated that, for many of the CBC components, blood counts were on average slightly lower in the Porter Ranch zip code than in three comparison zip codes. Based on these findings, Public Health agreed to pursue data from a larger clinical laboratory to conduct a more detailed exploratory analysis and include children. Although this exploratory analysis is separate from the Aliso Canyon Disaster Health Research Study (Health Study), the results of the exploratory analysis may inform other future research including research that is conducted as part of the Health Study. A report on the results titled Exploratory Analysis of Selected Blood Test Results Among Residents of Porter Ranch and Two Control Populations, 2011-2019, is available on the Historical Data page of the Health Study website.
The analysis did not find evidence of an impact of the Aliso Canyon blowout on mean values of selected blood test results among the adults and children in Porter Ranch who had blood tests conducted by Quest Diagnostics during the period of 2011 to 2019. However, the data used in the analysis had significant limitations, as described in the report. Therefore, the results by themselves are not sufficient to conclude that blood components in Porter Ranch residents were or were not affected by the blowout.
Although this exploratory analysis is separate from the Health Study, the findings may be used by the Health Study researchers, or by other researchers, to inform any future research in this area.
The UCLA research team selected to conduct the Health Study will be conducting analyses of cancer in the communities surrounding the Aliso Canyon underground gas storage facility. For more information on UCLA's analysis, refer to their scope of work beginning on page 133 of the document linked here .
Additionally, in advance of the Health Study, Public Health connected Community Advisory Group (CAG) members with researchers at the USC Cancer Surveillance Program (CSP), the population-based cancer registry for Los Angeles County, which routinely responds to community concerns regarding cancer occurrences. The CSP collects and analyzes information on all new cancer diagnoses made among residents of the County. Through a series of conversations with the CAG members, the CSP developed an analysis plan with approved methods developed by the Centers for Disease Control and Prevention (CDC). The analysis was intended to be conducted by the CSP in advance of, and separate from, the Health Study to determine whether cancer rates in communities surrounding Aliso Canyon are higher than expected by comparing the rates to those in Los Angeles County and/or the State of California, which is a standard practice to control for factors that contribute to cancer risk. While the CAG did not decide to move forward with the proposed analysis, the USC CSP remains an available resource for residents and/or communities who have concerns about cancer.
LA County and other local, state, and federal agencies are working to monitor the environment and health outcomes and protect you, your health, and the environment. There are many public agencies that are responsible for making sure different laws and regulations are followed, and it can be confusing to figure out where to report a problem. Learn more about which Local Agencies to call for problems in your community. Please also check out the SoCal Gas Regulators webpage for more information.
For information and updates on the Health Study, please sign up for email updates through our Web Form. The UCLA research team who was selected to conduct the Health Study will update the community on opportunities for community involvement in the near future. Please visit UCLA's Health Study website for updates and more information.
