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Final Program


Final Program

ACE 2025

WAST

Vapor Intrusion and Methane Hazards

Not Just a Climate Problem: The Safety and Health Risks of Methane Super-Emitter Events

Tuesday, June 10, 2025
2:30pm – 2:50pm ET
Location: 306C
Abstract Description: Methane super-emitter events (>100 kg hr-1) are prevalent across the oil and gas supply chain and are being targeted for methane mitigation policies due to their climate impacts; however, less is known about their direct safety, air quality, and public health risks. Here, we present an approach to assess risks from upstream oil and gas methane super-emitter events by combining geolocated methane emissions rates from satellite and aircraft data, regulatory-grade air dispersion modeling, and modeled gas composition to estimate one-hour average, source-attributable surface-level air concentrations of benzene and other key NMVOCs (toluene, ethylbenzene, xylenes, and hexane). We assess when and where hourly modeled methane and NMVOC air concentrations exceeded national safety (0.5% methane) and state-based health (8 ppb and 53 ppb benzene) benchmarks.

Thus far, we’ve applied this approach to seven methane super-emitter events as preliminary case studies. We’ve found that large methane super-emitters (>10,000 kg hr-1) had safety benchmark exceedances as far as 270 m from the source, indicating that safety risks are greatest for facility workers and nearby communities. Health benchmark exceedances were the greatest and most frequent close to the source ( < 300 m), but, in contrast to the safety risks, reached beyond one kilometer (1.1-19 km) for modeled super-emitters (210-15,800 kg hr-1), likely posing health risks to residents and sensitive populations. We also found that smaller super-emitters may pose outsized health risks due to the impact of site specific factors such as gas composition, meteorology, and terrain.

Recent advancements in satellite methane detection technology have greatly increased the number of publicly available geolocated methane plume observations with derived emissions rate data. To best leverage these advancements, we also present an automated cloud-based data management pipeline that allows for near-real-time dispersion modeling of methane and NMVOC concentrations that allows us to apply the above approach to assess the health and safety risks of hundreds to thousands of plumes. Increasing our case study dataset allows us to better support discussions on environmental justice, policies, and early detection and response efforts on methane super-emitters.