Personal inhalation risk assessment based on a hybrid method using CFD-CSP-PBTK modelling: Quantification of time-Averaged and peak concentration differences

Human health has been intimately linked to the indoor environment, highlighting the relevance of indoor air quality (IAQ). Although various techniques have been developed to maintain the well-being of building residents/workers, a convergence between IAQ and personal inhalation exposure risk under realistic conditions has yet to be achieved due to the heterogeneous nature of contaminant transfer. In this regard, computational fluid dynamics (CFD) is a promising tool when analysing detailed three-dimensional flow and gas-phase contaminant transport in a building. From this viewpoint, this study performs a comprehensive inhalation exposure analysis in the working environment, integrating outdoor airflow to the indoor environment of a factory under cross-ventilation for an 8-hour occupational period, a factory worker in the form of a computer simulated person (CSP) and a semi-coupled virtual respiratory tract. A physiologically-based toxicokinetic (PBTK) model has been added to the respiratory tract to predict tissue dose distribution, i.e., inhalation exposure risk. Three cases were analysed to confirm the differences between maximum/minimum and time-Averaged inhaled dose for a comprehensive source-To-dose study. Results confirmed the relevance of calculated personal inhalation exposure for an accurate time-Averaged intake and the danger of acute exposures at given times of a working day.