Secondary organic aerosol formation initiated by α-terpineol ozonolysis in indoor air

Secondary organic aerosol (SOA) owing to reactive organic gas (ROG) ozonolysis can be an important indoor particle source. However, SOA formation owing to ozonolysis of α-terpineol, which is emitted by consumer product usage and reacts strongly with ozone, has not been systematically quantified. Therefore, we conducted 21 experiments to investigate the SOA formation initiated by α-terpineol ozonolysis for high (0.84 h^-1 ), moderate (0.61 h^-1 ), and low (0.36 h^-1 ) air exchange rates (AER), which is the frequency with which indoor is replaced by outdoor air. α-Terpineol concentrations of 6.39 to 226 ppb were combined with high ozone (~25 ppm) to ensure rapid and complete ozonolysis. No reactants were replenished, so SOA peaked quickly and then decreased due to AER and surface losses, and peak SOA ranged from 2.03 to 281 μg/m³ at unit density. SOA mass formation was parameterized with the aerosol mass fraction (AMF), a.k.a. the SOA yield, and AMFs ranged from 0.056 to 0.24. The AMFs strongly and positively correlated with reacted α-terpineol, whereas they weakly and negatively correlated with higher AERs. One-product, two-product, and volatility basis set (VBS) models were fit to the AMF data. Predictive modeling demonstrated that α-terpineol ozonolysis could meaningfully form SOA in indoor air.