Towards enabling accurate evaluation of inhaled exposure

Inhaled exposure, in addition to skin exposure, is an important way of human exposure to air pollutants including both gaseous and particulate mediums containing chemical and/or biological matters. The accurate evaluation of inhaled exposure may involve at least two key issues. The first is related to the cyclic breathing pattern, namely inhalation, exhalation, and break, where the exposure during only the inhalation periods is the real exposure. However, accurate separation of the breathing cycles and measurement during only the inhalations are difficult tasks. The second is related to the location of sampling, namely at where the sampling and measurements should be made. The mouth or nostrils should be the location, but this is not always feasible during especially experimental measurements. In addition, the application in real-world practices of measurement at mouth and nostrils may be difficult. The study intends to address these two issues in both experimental and numerical contexts. For experiments, a breathing thermal manikin is used to reveal the concentration distribution of pollutants around the mouth/nose area and to examine the sampling methods (synchronized, selective, and continuous sampling methods). Similar to the experiments, a numerical breathing thermal manikin is developed to investigate the location and the way of sampling and measurement. This study provides the accurate sampling method of inhaled exposure. The obtained results are useful for the development of wearable devices for accurate exposure assessment and personalized environmental control systems.