Comment on “Unexpected Epoxide Formation in the Gas-Phase Photooxidation of Isoprene”

Paulot et al . (Reports, 7 August 2009, p. 730) reported that the photooxidation of isoprene under low–nitrogen oxides (NO x ) conditions produces epoxides that can facilitate the formation of secondary organic aerosol (SOA). However, another pathway involving the formation of methyl-butenediol intermediates can also lead to isoprene-derived SOA formation. Further research is needed to clarify the fate of isoprene in the atmosphere.