Heterogeneous formation of chloride atoms from NaCl in a photosmog system

A formation of atomic Cl is observed from NaCl aerosol in a photochemical smog in the absence and presence of NO sub x. A depletion of Ce- from the aerosol by intrusion of HNO sub 3 is observed to release HCl gas that is oxidized by O sub 3 in a heterogeneous reaction occuring on humid glass and quartz surfaces to produce molecular Cl sub 2, the photolytic precursor of atomic Cl. The heterogeneous nature of the process is demonstrated by investigating the oxidation of HCl gas by 0 sub 3 in the absence and presence of SiO sub 2 aerosol (aerosil) in a teflon bag.