⁵⁸The measures used to mitigate nitric oxide emissions are the same measures used to mitigate the other oxides of nitrogen: reduce combustion temperature, and/or reduce the NO_x compounds to elemental nitrogen by mixing the combustion exhaust gases with ammonia (NH₃) in the presence of a catalyst. So here we have a case where we really don’t care to distinguish NO from NO_x: we want to measure it all.