Location and abundance of oil and natural gas wells in the State of Colorado in 01/01/2017 (data from the Colorado Oil & Gas Conservation Commission, interactive map). Brown dots depict individual well locations. Also shown, by the red lines, are the borders of the DMA/NCFR ozone NAA. Red circles are used as indicators for Mesa Verde National Park, Golden – National Renewable Energy Labs (NREL), and Welby, which are the sites chosen for the data examples shown in this paper. DOI: https://doi.org/10.1525/elementa.300.f1