Ambient forest air was oxidized by OH, O3
, or NO3
inside an oxidation flow reactor, leading to formation of particulate matter from any gaseous precursors found in the air. Closure was achieved between the amount of particulate mass formed from O3
oxidation and the amount predicted from speciated gaseous precursors, which was in contrast to previous results for OH oxidation (Palm et al. ACP 2016). Elemental analysis of the particulate mass formed in the reactor is presented.