C10–C12 aromatics dominate ozone and secondary organic aerosol formation potential in emissions from printed circuit board manufacturing

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High-carbon aromatic hydrocarbons are under-characterized precursors of ozone and secondary organic aerosol (SOA) from solvent-intensive industries. We investigated aromatic emissions from 20 printed circuit board (PCB) manufacturing factories in the Pearl River Delta, China, using sorbent-tube samples collected from major production processes and exhaust outlets. Thermal desorption-gas chromatography/mass spectrometry was used to quantify 15 conventional C6–C9 volatile aromatic hydrocarbons (VAHs), 34 C10–C12 intermediate-volatility aromatic hydrocarbons (IAHs), and additional polycyclic aromatic hydrocarbons including naphthalene. Across process units, total aromatic concentrations ranged from 6.01 to 3,3924 μg/m 3 , and IAHs accounted for more than 71 % of measured aromatics, with IAHs/VAHs ratios of 3.37–7.30 across process units and a mean sample-wise ratio of 7.76 across 30 exhaust outlets. At the outlets, the ozone and SOA formation potentials of IAHs were on average 5.97 and 3.04 times the corresponding values of VAHs, respectively. Isodurene and ethyl-substituted xylene isomers dominated outlet concentration and ozone formation potentials, whereas naphthalene, toluene, and xylenes remained important for SOA formation potentials. These concentration- and profile-based results identify PCB manufacturing as a distinctive and under-characterized source of high-carbon aromatic precursors, and support including these species in industrial emission profiling, future emission-factor development, and control assessment.