Fig. 3. Gas-phase secondary oxidation products observed via PTR-ToF-MS measurements.

Gray shading corresponds to active periods of mopping and wiping during the cleaning events. Primary monoterpene and monoterpenoid emissions (A), most likely composed of limonene, α-pinene, β-pinene, and camphene (table S1), which cannot be differentiated using PTR-ToF-MS. Other gas-phase species in (B) to (D) were observed to have a slight delay in the appearance of their peaks, with respect to the mopping period and monoterpene peak, which is indicative of being a product of secondary chemical processes. Possible structures of the oxidation products are shown in table S2. Chemical pathways leading to secondary oxidation products in (B) to (D) are shown in figs. S3 and S4.