Key Considerations in Designing and Reviewing Air Quality Studies of Unconventional Natural Gas Development

摘要

1. Given the growth in unconventional natural gas development (UNGD, also commonly referred to as hydraulic fracturing) in the past decade, there has been growing interest in assessing the air quality impacts of UNGD and mitigating adverse impacts to nearby residents. This presentation is intended provide the audience a framework for designing and reviewing UNGD air quality studies and research. In the past decade, air quality research studies of UNGD in different regions in the US have drawn different conclusions about whether UNGD activities may result in adverse air quality and health impacts. Given differences in study designs and objectives, it is important to review the study results in context. Based on insights gained from site-specific air quality monitoring and modeling in different UNGD locations, including well sites and compressor stations, we present key considerations when designing or reviewing an UNGD air quality study that evaluates potential off-site pollutant exposures. This presentation discusses the selection of compounds of concern and associated health-based benchmarks, off-site study locations, and time periods of interest, which may vary depending on the objective of the study. For example, an evaluation of diesel exhaust and fugitive dust emissions from trucks and other vehicles would likely be more important for an air quality study of the drilling phase than the production phase. The types and nature of on-site emission sources (including their temporal nature), emissions control equipment and work practices, produced fluid composition, local terrain, meteorology, and location of off-site populations are site-specific factors that affect exposures and limit the ability to extrapolate findings from one study to draw conclusions about impacts in another setting. Developments in green completion technology, emission controls for storage tanks, improved work practices, and advanced leak monitoring techniques adopted by UNGD operators provide motivation for new and ongoing air quality studies that can help to assess the impacts of these strategies on air quality and public health.