Estimated impact of the Aliso Canyon disaster on emergency department visits

The largest natural gas disaster in the US occurred when the gas storage well at the Aliso Canyon natural gas storage facility ruptured on 10/23/2015 and released about 109,000 metric tons of airborne pollutants until 2/18/2016 when the well was capped. We used the California emergency department (ED) visit data to examine whether exposure to pollutants increased the rate of visits. We 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). We further measured ED visits for the primary diagnosis for conditions and symptoms that are associated with such exposure. We examined visits during 10/2013 to 4/2014 or "before", 10/2015 to 4/2016 or "during", and 10/2016 to 4/2017 or "after" the blowout. We used the quasi-experimental design to examine the impact of the blowout on ED visits from before to during and after the blowout. We developed ordinary least square regression models controlling for demographics and insurance coverage. We found that the affected community had 26 (confidence interval: 18.5, 33.5) 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 (3.4, CI:1.4, 5.5), anxiety and stress-related disorders (1.3, CI: 0.5, 2.1), respiratory-related symptoms (2.7, CI:1.6, 3.9), and gastrointestinal-related symptoms (5.4, CI: 3.6, 7.2) 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.