A mathematical hybrid-showering model was developed in order to describe the dynamic behaviour of volatile organic compounds (VOCs) contained in shower water during personal showering. The approach involves assuming a two-film theory and taking into account the dual flow patterns of "jet" and "spray" from a showerhead in order to estimate the emission of VOCs from tap water to air. The liquid-phase mass-transfer coefficients corresponding to both flow patterns and the gas-phase mass-transfer coefficient for spray droplets are estimated using the penetration theory, while the gas-phase mass-transfer coefficient for a jet-flow stream is calculated using an analogous empirical correlation. Literature-derived data were used to test the validity of the hybrid-showering model and a good correlation between literature-derived and calculated data was obtained. This study confirms the usefulness of the hybrid-showering modelling approach as regards the risk assessment of personal showering. Moreover, our simulated findings indicated that the jet-flow type showerhead should be more beneficial than the spray type showerhead as regards being associated with a lower VOC exposure risk. (C) 2003 Elsevier Ltd. All rights reserved.
