Emergency department use rose significantly during and after the 2015–16 Aliso Canyon gas blowout, according to a new paper from the UCLA Aliso Canyon Disaster Health Research Study.

Data showed that people living downwind of the blowout had 26 more emergency department visits per 1,000 residents from before to during the disaster, compared with the same time frame in a demographically similar comparison community.

That surge remained similarly high a year later.

ED visits for acute respiratory infections, anxiety and stress-related disorders, respiratory-related symptoms, and gastrointestinal-related symptoms, all of which are associated with exposure to hazardous air pollutants, increased from before the blowout to during the blowout in the affected community versus the comparison community.

During the 112-day blowout at the Aliso Canyon natural gas storage facility, approximately 109,000 metric tons of methane in addition to other hazardous air pollutants, including benzene, were emitted into the atmosphere near the Porter Ranch neighborhood in northwestern Los Angeles County. Residents also reported a visible oily residue deposited on buildings and vehicles.

“Our study is the first one to examine the broad health impacts of exposure to hazardous air pollutants during the blowout on residents of the affected community. Visits to the emergency department reflect the urgency and intensity of residents’ reactions to these pollutants,” said Nadereh Pourat, PhD, director of the Health Economics and Evaluation Research Program at the UCLA Center for Health Policy Research and lead author of the study, which was published today in the peer-reviewed journal Environment International.

Comparing the affected community with a demographically similar community allowed the researchers to isolate the disaster’s health effects on residents, Pourat said. To conduct their study, the researchers used data from the California Department of Health Care Access and Information to compare emergency department visits before, during and after the disaster for the affected and comparison communities.

The “before” period was October 2013 to April 2014, “during” was October 2015 to April 2016, and “after” was October 2016 to April 2017. Although the blowout at the facility ended on Feb. 11, 2016, extending the “during” period through April allowed the researchers to examine ED visits after people may have been exposed to pollutants that were still present on surfaces or in the air once they returned to their homes. Additionally, by comparing the same months during each time period, UCLA accounts for seasonal change in emergency department visits.

Rates of emergency department visits before the blowout in the areas downwind of the facility and the comparison community were similar, according to the study. While ED visits in the affected community increased more than the comparison community on average by 26 visits per 1,000 residents during the blowout, the increase spiked to as high as 48.7 more visits per 1,000 residents in February 2016 and 42.8 more visits per 1,000 in March 2016.

When examining symptoms and conditions associated with exposure to hazardous air pollutants, the researchers observed the following increases in ED visits per 1,000 residents in the affected community during the blowout versus the comparison community:

• acute respiratory infections: 3.4 more visits per 1,000 residents
• anxiety and stress-related disorders: 1.3 more visits per 1,000 residents
• respiratory-related symptoms: 2.7 more visits per 1,000 residents
• gastrointestinal-related symptoms: 5.4 more visits per 1,000 residents

Emergency department visits for acute respiratory infections showed the largest significant increase in February 2016. The affected community saw 14.8 more visits per 1,000 residents that month versus February 2015, compared with the same time frame in the comparison community. Visits for gastrointestinal symptoms spiked in January 2016, with 8.9 more visits per 1,000 residents compared to January 2015 and the comparison community.

“Our findings provide important insights into the health consequences of high levels of exposure to hazardous and toxic air pollutants,” Pourat said. “These findings highlight the importance of prioritizing the safety of communities living around natural gas storage facilities.”

As part of a five-year contract with the Los Angeles County Department of Public Health, the UCLA-led Aliso Canyon Disaster Health Research Study has been studying the short- and long-term health effects of the Aliso Canyon disaster, the largest uncontrolled release from an underground gas storage facility in U.S. history.