Modeling the formation and growth of organic films on indoor surfaces

Emission, transport, and fate of semi-volatile organic compounds (SVOCs), which include plasticizers, flame retardants, pesticides, biocides, and oxidation products of volatile organic compounds, are influenced in part by their tendency to sorb to indoor surfaces. A thin organic film enhances this effect, because it acts as both an SVOC sink and a source, thus potentially prolonging human exposure. Unfortunately, our ability to describe the initial formation and subsequent growth of organic films on indoor surfaces is limited. To overcome this gap, we propose a mass transfer model accounting for adsorption, condensation, and absorption of multiple gas-phase SVOCs on impervious, vertical indoor surfaces. Further model development and experimental research are needed including more realistic scenarios accounting for surface heterogeneity, non-ideal organic mixtures, and particle deposition.