Predicting the fate and transport of indoor DEHP considering their interaction with particles under different ventilation modes

Abstract

Ventilation are widely used in residential buildings to dilute indoor pollutants. While the dynamic partition model of semi-volatile organic compounds (SVOCs) for homes with a central forced-air handling system is still far from adequate. Here we developed a mechanistic model of SVOCs considering dynamic behaviours of size-resolved particles brought by ventilation. In this model, effects of air changes per hour (ACH) and secondary source of particles on mass transfer coefficient of source surfaces (hms) are considered. Three factors, namely ventilation mode, fresh air ratio and filtration efficiency are examined in detail, to figure out the time-varying multi-phase concentration of di-2-ethylhexyl phthalate (DEHP). Results show that with identical ACH (total ventilation rate/volume), the increase of indoor-outdoor air exchange rate (AER_I/O), would decrease the gas-phase concentration of DEHP, and would significantly shorten the time for the multi-phase DEHP to reach equilibrium concentration. The multi-phase (including the gas-phase, particle-phase and dust-phase) equilibrium concentration of DEHP indoors decreases with the increased fresh air ratio, taking into account the combined effect of ventilation dilution and particle-enhanced source emission. With the increase of filtration efficiency, the particle-phase equilibrium concentration of DEHP decreases, while the gas-phase equilibrium concentration of DEHP increases. Overall, the dynamic model is helpful to improve understandings of SVOCs’ interactions with airborne particles caused by ventilation systems, and clarify the key ventilation factors affecting the time-varying multi-phase concentration of SVOCs.