Indoor Secondary Organic Aerosol Formation Initiated from Reactions between Ozone and Surface-Sorbed d‑Limonene

Reactions between ozone and terpenoids produce numerous products, some of which may form secondary organic aerosol (SOA). This work investigated the contribution to gas-phase SOA formation of ozone reactions with surface-sorbed d-limonene, which is common indoors. A model framework was developed to predict SOA mass formation because of ozone/terpenoid surface reactions, and it was used with steady state experiments in a 283 L chamber to determine the aerosol mass fraction of SOA resulting from surface reactions, ξ_s (the ratio of mass of SOA formed and mass of ozone consumed by ozone/terpenoid surface reactions), for ozone/d-limonene reactions on stainless steel. The ξ_s = 0.70–0.91, with lower relative humidity leading to both higher mass and number formation. Also, surface reactions promoted nucleation more than gas-phase reactions, and number formation due to surface reactions and gas-phase reactions were 126–339 and 51.1–60.2 no./cm³ per μg/m³ of formed SOA, respectively. We also used the model framework to predict that indoor spaces in which ozone/d-limonene surface reactions would likely lead to meaningful gas-phase SOA formation are those with surfaces that have low original reactivity with ozone, such as glass, sealed materials, or smooth metals.