The largest natural gas disaster in the U.S. occurred when the gas storage well at the Aliso Canyon natural gas storage facility ruptured on 10/23/2015, releasing about 109,000 metric tons of pollutants into the air until 2/18/2016 when the well was capped.

Authors used California emergency department (ED) visit data to examine whether exposure to pollutants increased the rate of visits. They measured ED visits per 1,000 residents of the affected community living downwind of the well and a comparison group of residents with similar demographic and environmental characteristics (524,508). ED visits for the primary diagnosis for conditions and symptoms that are associated with such exposure were measured, and visits from 10/2013 to 4/2014 (“before”), 10/2015 to 4/2016 (“during”), or 10/2016 to 4/2017 (“after”) the blowout were examined. Quasi-experimental design was used to examine the impact of the blowout on ED visits from before to during and after the blowout and ordinary least square regression models were developed to control for demographics and insurance coverage.

Findings: The affected community had 26 more ED visits per 1,000 from before to during the blowout than the comparison community and this rate remained elevated after the blowout. We also found more ED visits for acute respiratory infections, anxiety and stress-related disorders, respiratory-related symptoms, and gastrointestinal-related symptoms and these rates also remained elevated. Our findings highlight the importance of understanding all possible public health and societal risks of continued reliance on natural gas and its contribution to climate change.

Nadereh Pourat, associate center director at UCLA CHPR, is lead author of this study.