The lifetime of nitrogen oxides (NOx
) is evaluated by analysis of field measurements from the southeast United States. At warm temperatures in the daytime boundary layer, NOx
interconverts rapidly with both PAN and alkyl and multifunctional nitrates (RONO2
), and the relevant lifetime is the combined lifetime of these three classes. We find that the production of RONO2
, followed by hydrolysis to produce nitric acid, is the dominant pathway for NOx
removal in an isoprene dominated forest.