Measurement of NO3 and N2O5 in a Residential Kitchen

We present direct indoor measurements of the nitrate radical (NO 3 ) and dinitrogen pentoxide (N 2 O 5 ) produced from combustion cooking emissions in a residential kitchen. When the indoor ozone (O 3 ) concentration was low (∼4 ppbv), nitric oxide (NO) emitted from gas stove combustion suppressed NO 3 formation. However, at moderate O 3 levels (∼40 ppbv), measured NO 3 concentrations reached 3–4 pptv, and the indoor NO 3 reactivity loss rate coefficient reached 0.8 s –1 . A box model of known chemistry agrees with the reactivity estimate and shows that moderate O 3 levels led to a nitrate radical production rate of 7 ppbv h –1 . These indoor NO 3 production rates and reactivities are much higher than those typically found outdoors. We conclude that at low O 3 levels indoor combustion suppresses nitrate radical chemistry, but when sufficient O 3 enters residences from outdoors or is emitted directly from indoor sources, gas stove combustion emissions promote indoor NO 3 chemistry.