Impact of indoor ventilation efficiency on acetone inhalation exposure concentration and tissue dose in respiratory tract

A significant feature of the indoor environment is the heterogeneity of airflow and pollutant distributions, which are primarily dependent on ventilation systems. In the case of short- and high-concentration exposures to hazardous chemical pollutants, it may be necessary to precisely determine the concentration in the breathing zone or, more directly, the inhalation exposure concentration in the respiratory tract, rather than the representative room average concentration in an indoor environment, because of the non-uniformity of pollutant concentration distributions. In this study, we developed a computer-simulated person with a detailed respiratory system to predict inhalation exposure concentration and inhalation dose via transient breathing and reported a demonstrative numerical simulation for analyzing acetone concentration distributions in a simplified model room. Our numerical analysis revealed that the ventilation efficiency distribution in a room could change significantly by changing the design of the ventilation system, and that the inhalation exposure concentration estimated by a computer-simulated person could differ from the representative concentration, such as perfect-mixing or volume-averaged acetone concentration, by a factor of two or more.