Impact of U.S. Oil and Natural Gas Emission Increases on Surface Ozone Is Most Pronounced in the Central United States

Abstract

Observations of volatile organic compounds (VOCs) from a surface sampling network and simulation results from the EMAC (ECHAM5/MESSy for Atmospheric Chemistry) model were analyzed to assess the impact of increased emissions of VOCs and nitrogen oxides from U.S. oil and natural gas (O&NG) sources on air quality. In the first step, the VOC observations were used to optimize the magnitude and distribution of atmospheric ethane and higher-alkane VOC emissions in the model inventory for the base year 2009. Observation-based increases of the emissions of VOCs and NO x stemming from U.S. oil and natural gas (O&NG) sources during 2009–2014 were then added to the model, and a set of sensitivity runs was conducted for assessing the influence of the increased emissions on summer surface ozone levels. For the year 2014, the added O&NG emissions are predicted to affect surface ozone across a large geographical scale in the United States. These emissions are responsible for an increased number of days when the averaged 8-h ozone values exceed 70 ppb, with the highest sensitivity being in the central and midwestern United States, where most of the O&NG growth has occurred. These findings demonstrate that O&NG emissions significantly affect the air quality across most of the United States, can regionally offset reductions of ozone precursor emissions made in other sectors, and can have a determining influence on a region’s ability to meet National Ambient Air Quality Standard (NAAQS) obligations for ozone.

The Fires, Asian, and Stratospheric Transport-Las Vegas Ozone Study (FAST-LVOS)

“…The 4MDA8 O3 decreased from 83 to 63 ppbv in the SEUS, but only decreased from 77 to 69 ppbv in the SWUS (Utah, Arizona, Colorado, and New Mexico). The weaker response to NO2 reductions in the SWUS is attributed in part to increased oil and gas development (Pozzer et al, 2020) and in part to the much higher background O3 in this region (EPA, 2013;Lefohn et al, Since stratospheric intrusions do not typically reach the relatively low elevations of Las Vegas (620 m a.s.l.) it was hypothesized that some of the high O3 episodes resulted from entrainment of mid-tropospheric O3 layers (Langford et al, 2017) by the deep convective boundary layers that form over the Mojave Desert (Seidel et al, 2012).…”

Variations in Sources, Composition, and Exposure Risks of PM2.5 in both Pre-Heating and Heating Seasons

“…On average, SO4 2and NO3 -(in µg m -3 ) varied from 1.16 to 8.98 and from 1.05 to 29.1 in the PHS, and from 1.38 to 42.4 and from 1.73 to 43.4 in the HS. A high N/S ratio of 2.29 during the entire sampling period (ESP) in Baoding suggested the CTG impacts the emissions of SO4 2and NO3 - (Pozzer et al, 2020). The N/S ratios in Baoding were much higher than 0.95 in 2016 for Shijiazhuang , and 1.28 for the background site in the North China Plain (Yao et al, 2016).…”

The <i>Fires, Asian, and Stratospheric Transport</i>–Las Vegas Ozone Study (<i>FAST</i>-LVOS)

“…These deep LC2 (lifecycle 2) intrusions (Thorncroft et al, 1993;Polvani and Esler, 2007) often reach the top of the boundary layer and sometimes even the surface at higher elevations (Schuepbach et al, 1999;Stohl et al, 2000;Bonasoni et al, 2000;Trickl et al, 2020). These intrusions were first described by Reed and Danielsen (1958) and have long been observed as steeply sloping tongues in ozone lidar curtains (Browell et al, 1987;Ancellet et al, 1994;Vaughan et al, 1994;Langford et al, 1996;Eisele et al, 1999).…”

“…The 4MDA8 O 3 decreased from 83 to 63 ppbv in the SEUS but only decreased from 77 to 69 ppbv in the SWUS. The weaker response to NO 2 reductions in the SWUS is attributed in part to increased oil and gas development (Pozzer et al, 2020) and in part to the much higher background O 3 in this region (EPA, 2013;Lefohn et al, 2014;Cooper et al, 2015). This background is derived from a variety of non-controllable ozone sources (NCOSs) including O 3 produced by photochemical reactions of anthropogenic emissions outside the US borders or by soils, vegetation, lightning, or wildfires and by naturally occurring O 3 transported downward from the stratosphere (Jaffe et al, 2018).…”