Community Monitoring around the Porter Ranch Natural Gas Leak Disaster

Abstract

On October 23, 2015, a massive natural gas leak occurred at the Aliso Canyon natural gas storage facility near the community of Porter Ranch in Los Angeles, California. This event lasted 110 days and resulted in one of the largest anthropogenic releases of natural gas from a point source ever recorded. More than 6000 people were evacuated from the area. Air toxics – including benzene (C6H6), n-hexane C6H14, and hydrogen sulfide (H2S) − were observed at elevated levels in Porter Ranch. We conducted air quality monitoring at homes and schools across the community. We deployed two rounds of volatile organic compound (VOC) monitors between January 13 and February 12. TraceAir passive badges (Assay Technology) were placed at 19 locations around Porter Ranch in two rounds of two weeks. Hydrogen sulfide passive badges (Radiello) were co-located with VOC badges at 10 locations. Sensor Networks for Air Quality (SNAQ) monitors developed by Cambridge University were deployed at six locations and measured several pollutants every 10 seconds, including: carbon monoxide (CO), nitrogen oxide (NO), ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon dioxide (CO2) and total volatile organic compounds (VOCs). The monitors also measured particles via optical sensors ranging from 0.43 – 17.4 µm. In contrast to the first month of the disaster, we found very low levels of VOCs and H2S for the month our monitors were deployed. We observed marked differences in the temporal patterns of particles at locations near the leak site and downwind compared to those farther away or in an upwind direction. The elevated particles, many in smaller size fractions, suggest that the population living near the site could have been exposed to primary and secondary organic particles attributable to gas leak, which could generate health effects. The exposed population will likely require surveillance in the future to detect anomalies in health status and disease incidence.