Methyl- and dimethyl-/ethyl-nitronaphthalenes measured in ambient air in Southern California

Naphthalene and alkylnaphthalenes are abundant semi-volatile polycyclic aromatic hydrocarbons (PAHs) present in ambient air as a result of emissions from combustion sources. At ambient temperatures, these PAHs can undergo atmospheric gas-phase reactions with hydroxyl (OH) radicals. We report here on environmental chamber reactions simulating ambient photooxidation of volatilized diesel fuel PAHs and demonstrate for the first time that dimethylnitronaphthalenes and/or ethylnitronaphthalenes identified as formed from the OH radical-initiated reactions of alkyl-PAHs present in diesel fuel are also present in ambient air samples collected in Southern California.