Synthesis and health-based evaluation of ambient air monitoring data for the Marcellus Shale region

Abstract

In recent years, there has been a marked increase in the amount of ambient air quality data collected near Marcellus Shale oil and gas development (OGD) sites. We integrated air measurement data from over 30 datasets totaling approximately 200 sampling locations nearby to Marcellus Shale development sites, focusing on 11 air pollutants that can be associated with OGD operations: fine particulate matter (PM 2.5), nitrogen dioxide (NO 2), sulfur dioxide (SO 2), acetaldehyde, benzene, ethylbenzene, formaldehyde, n-hexane, toluene, xylenes, and hydrogen sulfide (H 2 S). We evaluated these data to determine whether there is evidence of community-level air quality impacts of potential health concern, making screening-level comparisons of air monitoring data with acute and chronic health-based air comparison values (HBACVs). Based on the available air monitoring data, we found that only a small fraction of measurements exceeded HBACVs, which is similar to findings from integrative air quality assessments for other shale gas plays. Therefore, the data indicate that air pollutant levels within the Marcellus Shale development region typically are below HBACV exceedance levels; however, the sporadic HBACV exceedances warrant further investigation to determine whether they may be related to specific site characteristics, or certain operations or sources. Like any air monitoring dataset, there is uncertainty as to how well the available Marcellus Shale air monitoring data characterize the range of potential exposures for people living nearby to OGD sites. Given the lesser amounts of air monitoring data available for locations within 1,000 feet of OGD sites as compared to locations between 0.2 and 1 miles, the presence of potential concentration hotspots cannot be ruled out. Additional air monitoring data, in particular more real-time data to further characterize short-term peak concentrations associated with episodic events, are needed to provide for more refined assessments of potential health risks from Marcellus Shale development. Implications: While there is now a sizable amount of ambient air monitoring data collected nearby to OGD activities in the Marcellus Shale region, these data are currently scattered among different databases and studies. As part of an integrative assessment of Marcellus Shale air quality impacts, ambient air data are compiled for a subset of criteria air pollutants and hazardous air pollutants that have been associated with OGD activities, and compared to acute and chronic health-based air comparison values to help assess the air-related public health impacts of Marcellus Shale development.

Assessing Agreement in Exposure Classification between Proximity-Based Metrics and Air Monitoring Data in Epidemiology Studies of Unconventional Resource Development

“…Secondly, our analysis was limited to only six pollutants, although additional pollutants associated with URD, particularly VOCs, have been a source of concern [37,38]. We included pollutants in the analysis that had been suggested as adversely impacting community health around URD operations, and for which ambient measurements were readily available from both state and federal sources [9,19].…”

“…This is a limitation of our analysis, as VOCs and other hazardous air pollutants have been highlighted in recent quantitative risk assessments [37,38,39,40]. Recent summaries of air monitoring data in Pennsylvania [38] and Colorado [39,40] have found only sporadic exceedances of health-based comparison values, however, interpretation of the risk posed by the measured concentrations can differ depending on the comparison values used [39]. These recent assessments also identified the relative scarcity of air toxics monitoring data as a limitation.…”

Evaluating potential human health risks from modeled inhalation exposures to volatile organic compounds emitted from oil and gas operations

“…The measurements were source-attributable because the facility's emission plume was identified with a mobile tracker, and other nearby chemical signals were removed via an upwind background monitor. This is in contrast to typical monitoring data (e.g., those used by Colborn et al 2014;Gilman et al 2013;Halliday et al 2016;Long, Briggs, and Bamgbose 2019;McKenzie et al 2018McKenzie et al , 2012McMullin et al 2018;Swarthout et al 2013;Thompson, Hueber, and Helmig 2014) which measure the ambient air both within and outside the plume (depending on conditions) and cannot necessarily differentiate a target source of emissions from other nearby emissions. Our stochastic approach to dispersion modeling, whereby we combined the on-sitemeasured emissions data with multiple datasets of variable meteorology, has the advantage of generating thousands of credible and representative short-and longterm VOC air-concentration scenarios at hundreds of possible exposure locationsmany more than can be reasonably observed with monitoring.…”

“…Studies have used such monitoring data to estimate exposures for people living near O&G operations. Long, Briggs, and Bamgbose (2019) did so for areas in Pennsylvania. For Coloradans within 0.5 miles of active wells in 2008, McKenzie et al (2012 used measurements along well-pad perimeters to make conclusions about incremental exposures to O&G-related hydrocarbon emissions: higher-end subchronic exposures could be slightly above health-criteria levels, while all other subchronic and chronic exposures were below noncancer criteria levels for individual critical-effect groups and chemicals, and cancer risks from individual chemicals were < 1 × 10 −5 .…”

Community Health Impacts From Natural Gas Pipeline Compressor Stations

“…Despite strong links between natural gas development and disease, compressor station chemical emissions data remains sparse. In order to fully understand the impacts of compressor station emissions, air quality should be measured in more locations with increased frequency (Long et al., 2019 ).…”