Data from: Influence of oil and gas emissions on ambient atmospheric non-methane hydrocarbons in residential areas of northeastern Colorado

The Northern Front Range (NFR) region of Colorado has experienced rapid
expansion of oil and gas extraction from shale and tight sands reservoirs
in recent years due to advances in hydraulic fracturing technology, with
over 24,000 wells currently in operation. This region has also been
designated as a federal ozone non-attainment area by the U.S. EPA. High
ozone levels are a significant health concern, as are potential health
impacts from chronic exposure to primary emissions of non-methane
hydrocarbons (NMHC) for residents living near wells. From measurements of
ambient atmospheric NMHC present in residential areas located in close
proximity to wells in Erie, Colorado, we find that the C2-C5 alkanes are
enhanced by a factor of 18 - 77 relative to the regional background, and
present at higher levels than typically found in large urban centers. When
combined with NMHC observations from downtown Denver and Platteville, it
is apparent that these compounds are elevated across the NFR, with highest
levels within the Greater Wattenberg Gas Field. This represents a large
area source for ozone precursors in the NFR. The BTEX aromatic compounds
in Erie were comparable to (e.g., benzene) or lower than (e.g., toluene,
ethylbenzene, xylene) in large urban centers, however, benzene was
significantly higher in Platteville, and within the range of chronic
health-based exposure levels. An initial look at comparisons with data
sets from previous years reveal that ambient levels for oil and
gas-related NMHC in Erie, as well as further downwind in Boulder, have not
decreased, but appear to have been increasing, despite tightening of
emissions standards for the oil and gas industries in 2008.