Determining benzene from tracer hydrocarbons. Correlations of benzene with acetylene (a), presumably dominated by car traffic, and propane (b), presumably dominated by oil and gas exploration related sources. Benzene is two to three times more abundant than expected, and acetylene correlates surprisingly well with propane (d), while benzene variability is explained to 95% through a multi-linear combination of tracer NMHC species of the dominant NMF factors (Figure 6). The data points highlighted in orange were associated with combustion plumes from local flares as close as 2 km to the south of the monitor in August 2015 (see text; Figure 9). DOI: https://doi.org/10.1525/elementa.289.f8