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 (C 3 H 4 O 3 ), glyceric acid (C 3 H 6 O 4 ), succinic acid (C 4 H 6 O 4 ), malic acid (C 4 H 6 O 5 ), tartaric acid (C 4 H 6 O 6 ), 2,3-dihydroxy-glutaric acid (C 5 H 8 O 6 ), glycolic acid (C 2 H 4 O 3 ) and oxalic acid (C 2 H 2 O 4 ) 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. • SOA products dominated by organic acids and diacids with carbon chain number in 2–5. • Main products in m -xylene analysis were glycolic, pyruvic, succinic and malic acid. • Bioreactivity in isoprene-derived SOA showed enhanced cytotoxicity and cell damage. • Correlation analysis showed high coefficients between compounds and bioreactivity. • Bioreactivity of malic acid could possibly relate to apoptotic properties of cells.