Airborne radioactivity in the New Mexico oil and gas development area of the Permian Basin

Airborne alpha radioactivity from both radon gas (gas-phase radioactivity) and radon progeny in particulates (particle-associated radioactivity) were investigated over 13 months (May 2023–May 2024) at a fixed site in Loving, NM (LNM), USA, located at the central-western edge of the Permian Basin where oil and gas (O&G) development has experienced rapid expansion over the past decade. Gas-phase, particle-associated, and total alpha radioactivity recordings had annual medians of 27, 11, and 40 Bq m−3, respectively, about 3–5 times higher than background levels when winds were from the north-northwest sector at speeds up to 4 m s−1. Two other wind direction sectors from the southwest and southeast were also associated with elevated total alpha radioactivity, ranging from 1.5 to 5 times above background levels. A variety of possible radon sources within a large footprint are suspected to contribute to the elevated airborne radioactivity. Besides natural sources, these include O&G industry emissions, such as gas flares at active well pads, gas-fired compressors at midstream sites, and produced water ponds. Linear regression analyses indicate that for every 10 flares within 50 km of LNM, airborne radioactivity may increase by 1.37% (95% CI: 0.41%–2.34%). Mean radioactivity levels for the whole study period were ≈20 Bq m−3 above that of background air transported into the study region, with this excess reflecting contributions from both natural and anthropogenic sources. If interpreted in the context of established epidemiological relationships between indoor radon exposure and lung cancer risk, this magnitude of enhancement could correspond to on the order of a few percent increase in lifetime lung cancer risk. These observations of airborne radioactivity increases underscore the need for targeted observations and quantification of contributing natural soil and O&G facility emissions, particularly from venting, flaring, emission stacks, and produced water storing ponds.