Key takeaways
- The 2015–2016 Aliso Canyon gas blowout harmed long-term individual mental health and community well-being, with effects that persist a decade later.
- Community focus groups defined a key disaster characteristic that shapes long-term mental health outcomes: invisibility
- The novel "Disaster Invisibility Framework," introduced in this study, is a way for public health researchers to assess and address the psychological, social and community impacts following disaster exposure.
A decade after the largest methane leak in U.S. history, a new study by UCLA and NYU researchers sheds light on the mental health impacts of the 2015–2016 Aliso Canyon natural gas disaster on residents of Porter Ranch and surrounding communities.
Drawing on a series of six focus groups with residents who lived within 5 miles of the gas leak wellhead, the research reveals persistent mental health symptoms — including emotional distress, anxiety, depression, anger and post-traumatic stress disorder — as well as a deep sense of abandonment and loss of trust in institutions.
"The Aliso Canyon methane blowout is a disaster that unfolded without the recognition or support that many other environmental crises often receive," said lead author Katie Lynch, a doctoral candidate in social and behavioral sciences at the NYU School of Global Public Health and a member of the UCLA Aliso Canyon Disaster Health Research Study team. "Across our focus groups, residents shared the often-invisible ways that this disaster affected their family and community in the 10 years since the blowout."
The study, which was published in the peer-reviewed journal Social Science & Medicine, introduces and explores the theme of "invisibility" in the context of disaster science.
"Our goal was to identify and articulate the multiple 'invisible' dimensions of the Aliso Canyon blowout as a framework for understanding the disaster's long-term psychological, social and community impacts," Lynch said.
Focus groups were conducted between March and June 2024. To better examine the different impacts of the disaster across life-course trajectories, focus groups were categorized by age — young (18–34), mid-age (35–64), and older (65-plus).
Researchers identified four dimensions of disaster invisibility which shaped long-term mental health:
Invisible risks: Most participants shared that their earliest memory of the blowout was the smell of gas, which gave them a sensory indication that something was "off," but delayed and conflicting communication by local authorities led them to feel that they were left to assess and manage their own risk. Parents reported experiencing long-term distress and guilt about whether they had made the "correct" choices for their families or unknowingly harmed their children.
Invisible harms: Unknowns about the exposure levels, length of exposure and potential health effects created a heightened state of health anxiety that continues today. Participants shared constant worry about whether they or loved ones might experience new physical symptoms or diagnoses, and whether these symptoms could be attributed to the disaster. Young adults in particular shared their worries about the long-term health effects of methane exposure.
Invisible community: Participants described persistent anger at a lack of corporate accountability and government response. While participants emphasized how the community initially came together, over time they felt abandoned by local institutions and unseen and unheard by news media.
Invisible changes: Participants experienced a loss of comfort and safety and altered life plans, exacerbated by uncertain future health status. Most participants in the mid-aged and young adult groups who remained in Porter Ranch shared their desire to relocate permanently, primarily due to fears about persistent exposure. Multiple members of the older adult focus groups shared that they chose to remain in Porter Ranch because they felt "guilty" selling their house to a young family, whose children may be more susceptible to environmental exposures.
Across all age groups, participants expressed uncertainty about the future and felt a lack of closure related to the blowout. Lingering unknowns about exposure levels, and anxiety about associated health effects for themselves and their loved ones is a persistent source of stress that has been detrimental to participants' long-term mental health and well-being.
The findings underscore the need for public and mental health systems to better address the long-term psychological and social consequences of environmental disasters — especially those that are not immediately visible. The study calls for expanded mental health services, transparent communication and long-term health monitoring for affected communities.
"Community perspectives have been integral to the study. The focus groups, for example, have informed both the Resident Health Survey and the clinical assessments," said study co-author Dr. David Eisenman, community stakeholders communications core lead for the Aliso Canyon Disaster Health Research Study and a professor at the David Geffen School of Medicine and UCLA Fielding School of Public Health. "The findings confirm the importance of listening to residents and understanding their lived experiences as crucial to understanding the full impact of environmental disasters."
This is the third peer-reviewed study published by the UCLA-led Aliso Canyon Disaster Health Research Study, which was awarded a five-year contract in November 2022 to assess the short- and long-term health effects of the gas blowout.
The first study, published in Science Advances, found that pregnant women living near the blowout had a nearly 50% higher-than-expected chance of having a low–birth-weight baby. The second study, published in Environmental Research Communications last month, used remote sensing to confirm methane plumes reached at least 6.2 miles downwind from the gas storage facility.
