Computer-simulated persons (CSPs) with respiratory systems have been developed for microclimate analysis around the human body and inhalation exposure analysis, for detailed assessment of comfort and health risks in indoor spaces. This study examined and validated the prediction accuracy of a CSP, for precise estimation of indoor environmental quality (IEQ). The flow-field prediction accuracy was thoroughly examined in a grid analysis using the CSP and a thermal manikin for benchmarking. The model incorporated unsteady breathing and human postural sway, and assessed their impact on the microclimate around the human body. The numerically estimated flow field was validated using experimental particle image velocimetry (PIV) data, with a detailed grid independence test. Considering the practical use of the respiratory tract model for the inhalation exposure risk assessment, the prediction accuracy of particle transport and deposition analysis was examined using previously published in vivo experimental results. This analysis revealed that the impact of transient breathing and body vibrations on the reproduction of the thermal plume around the human body is quite weak; consequently, these conditions can be ignored from the macroscopic perspective of indoor airflow analysis.

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The establishment of a healthy indoor environment requires the accurate evaluation of an individual’s exposure to pollutants. The concentration of indoor chemical pollutants is a representative indicator for such evaluation and is generally measured on-site. Moreover, material flow analysis (MFA), using macroscopic statistical data, is a reasonable method for objectively evaluating pollution on a wide scale; however, no effective strategy exists for the prediction of indoor air pollution, nor for the assessment of an individual’s exposure from social stock data. Accordingly, we developed a novel integration method comprising MFA and computational fluid dynamics (CFD) with a computer-simulated person (CSP) to establish a framework for evaluating indoor pollutant concentration and individual exposure of residents. We focused on diethyl-hexyl phthalate (DEHP) and first estimated the amount of DEHP-containing product accumulation in Japan by MFA. Second, we conducted a thorough survey and measurement of DEHP emission rates. Using these results as boundary conditions for indoor CFD with CSP, the individual exposure of a resident, in a standard residential house, was quantitatively evaluated. The total daily exposure per unit of body weight was estimated to be more than 100 (μg/kg/d) in the worst-case scenario which was considered the upper limit for exposure in this analysis.

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