UC Berkeley

Within the past decade, major technological advancements in oil and natural gas development have made extraction of hydrocarbon resources economically feasible. As the demand for oil and natural gas development increases, the public and regulatory agencies have become increasingly concerned about human and environmental impacts of the development and storage processes. Oil and natural gas operations are known sources of greenhouse gases and of emissions associated with adverse environmental and human health outcomes; however, research efforts aimed at understanding these impacts have been outpaced by the rapidly evolving technology and increased production efforts of the past decade. While recent research has provided insights into the impacts of oil and natural gas development, there is still limited information on the full range of potential exposures from the upstream process, and a dearth of literature on the impacts of emissions from natural gas storage.

Various attempts to identify and classify all products and chemicals used during the oil and natural gas development processes have resulted in disparate, and often contradictory, lists ranging from hundreds to thousands of chemical constituents. Chemicals of particular concern due to their potential to cause cancer and other serious health effects, have been categorized as hazardous air pollutants (HAPs) by the U.S. Environmental Protection Agency (U.S. EPA). To identify the full range of HAPs measured near upstream oil and natural gas development sites in recent scientific literature, we conducted a critical review of peer-reviewed research published between 2012 and 2018. From this review, we identified over 61 individual HAPs that have been investigated, of which 32 HAPs were collected as primary datasets. Additional efforts to recategorize sourced emissions found that the production phase, with its lengthy operation timeframe and episodic peak emission events, has the potential to emit the highest concentrations of associated HAPs over the longest time period. Results from chapter one provided the impetus for investigations included in the following chapters.

From the critical review conducted in chapter one, we identified a growing, yet still relatively small body of studies that investigates the relationship between the proximity of upstream oil and natural gas facilities and exposures to air pollutant emissions. With a dearth of scientific data, it is difficult to fully understand exposure risks and offer scientific guidance on specific adequate set-back requirements. In chapters two and three, we expanded our investigations to include the oil and natural gas air pollution exposure impact zones during upstream activities. From the evidence elucidated from the previous chapter, we targeted active oil and natural gas wells in the production phase and measured several indicative HAP compounds. We deployed passive samplers at varying distances along transects through upstream oil and natural gas development facilities to understand emission related gradient behaviors. Results along the sampled transects in semi-rural Colorado, suggest benzene, toluene, and n-hexane reach background concentrations at around 220 meters from the facilities. Additional measurements of various sized particles suggest PM can be measured in ambient air at distances as far as 560 meters from the facility fence line.

While much of the focus has been on the oil and natural gas development in rural and semi-rural regions, few studies have focused on emissions and the impact on human health in the state of California, where there are approximately 58,000 active wells. Despite the presence of multiple competing sources and the difficulties associated with deployment in dense urban environments, we were able to identify gradient behavior along the transect downwind of the target facility; correlate target HAPs with the natural gas tracer compound, n-pentane; and identify the added air quality exposure burden from the targeted facility. From these investigations, distance decay gradient samples suggest benzene and n-hexane reach background concentrations between 125 and 150 meters from the facility fence line within this dense urban environment.

The 2015 Aliso Canyon natural gas blowout provided a unique research opportunity to further our investigations during an on-going anthropogenic disaster event. Armed with the findings from the previous chapters, we focused our investigations on HAP compounds and speciated particles. Initial results revealed higher and more variable concentrations of particles in the outdoor air at locations close to the blowout site compared to those farther away. Subsequent sampling of indoor environments found a characteristic “fingerprint” of metals in the indoor dust samples similar to samples taken at the blowout site. Canonical correlation analyses of this metal signature showed that newer homes and homes with professionally installed weather proofing materials installed as a result of the blowout had lower metal concentrations. Additionally, we found compelling evidence that several HAPs were elevated in the surrounding communities of Porter Ranch during the blowout event, and final attempts to plug the well were associated with particle emissions. Taken together, our results suggest that the blowout and attempts to plug the well had a discernable effect on the indoor air environments of sampled homes.

The full understanding of human health impacts from exposures to underground natural gas storage related emissions remain tenuous. To the best of our knowledge, the work contained within the listed chapters is the first to investigate gradient behaviors around oil and natural gas development in downtown Los Angeles, to measure and characterize the impact zone of speciated particles near upstream activities, and to characterize potential exposures from particles from an anthropogenic natural gas storage blowout event. The current results expand on the dearth of studies examining impacts from oil and natural gas development and storage emissions, yet the need for additional research remains of high importance. We anticipate these results will serve as a guide for future research and help develop necessary policies to protect communities at risk of exposures from both routine and non-routine emission events.