Characterization of chemical and bioreactivity properties of photooxidation reaction products from secondary organic aerosols (SOA) under high OH exposure condition

The chemical and bioreactivity properties of photooxidation products emitted during high radical exposure conditions were characterized. The purpose was to simultaneously investigate the influences of the toxicity of photooxidation products from common anthropogenic and biogenic precursors (toluene, m-xylene and isoprene). The major ring-opening compounds were identified as pyruvic acid (C₃H₄O₃), glyceric acid (C₃H₆O₄), succinic acid (C₄H₆O₄), malic acid (C₄H₆O₅), tartaric acid (C₄H₆O₆), 2,3-dihydroxy-glutaric acid (C₅H₈O₆), glycolic acid (C₂H₄O₃) and oxalic acid (C₂H₂O₄) originated from the toluene and xylene-derived secondary organic aerosol (SOA) products in the analysis. The average LDH level from isoprene-derived SOA (0.77 μg/ml) was higher than the control (0.75 μg/ml) and the DCFH level from isoprene-derived SOA (228.73 RFU) was also higher than the control (215.18 RFU). In addition, the average LDH level from toluene-derived SOA (0.86 μg/ml) was higher than the isoprene (0.77 μg/ml). The IL-6 level from toluene-derived SOA (182.82 pg/ml) was higher than the xylene-derived SOA (173.00 pg/ml). These suggested enhanced cytotoxicity and cell membrane damage under toluene-derived SOA exposure. The isoprene-derived SOA induced higher DCFH levels of (228.73 RFU), implying the potential effects of particulate matter from SOA on the oxidative potential and rising cellular oxidant burden. The overall results suggest that the oxidation products can potentially cause various cytotoxic effects. This finding warrants further investigation into the toxicity profiles of SOA and regulation of SOA pollution.