An outdoor smog chamber and modeling study of toluene–NO_<i>x</i> photooxidation

Abstract

Abstract An experimental investigation of the gas‐phase photooxidation of toluene–NO x –air mixtures at part‐per‐million concentrations has been carried out in a 65‐m 3 , outdoor smog chamber to assess our understanding of the atmospheric chemistry of toluene. In addition, six CONO x –air irradiations were conducted to characterize the chamber with regard to any wall radical sources. Measured parameters in the toluene–NO x experiments included O 3 , NO, NO 2 , HNO 3 , peroxyacetyl nitrate (PAN), CO, toluene, benzaldehyde, o ‐cresol, m ‐nitrotoluene, peroxybenzoyl nitrate (PBZN), temperature, relative humidity, aerosol size distributions, and particulate organic carbon. Predictions of the reaction mechanism of Leone and Seinfeld [7] are found to be in good agreement with the data under a variety of initial conditions. Additional simulations are used to investigate various mechanistic pathways in areas where our understanding of toluene chemistry is still incomplete.