The N2O used was anesthetic grade, with O2 contamination specified as ≤ 0.2%. O2 also etches carbon NPs, but with TNP dependence quite different than that observed for N2O. For O2, reactivity was found to peak below 1600 K, dropping gradually at higher TNP, 1, 2 while for N2O, reactivity (below) was found to be small at 1600 K, increasing with TNP to 1900 K. Using the measured EEO2 values, and assuming O2 contamination at the upper limit, we can estimate that reaction with the O2 contaminant could have contributed as much as ~6% to EEN2O at 1700 K, dropping to ~2% by 1900 K. Given the uncertainties in EEN2O we conclude that the effects of the O2 contaminant were insignificant. The possible exception was in a single experiment at 1600 K, where reactivity toward N2O was found to be quite small, such that the contribution from the O2 contaminant could have been as much as ~20%.