Assessment of exposure effects of indoor particles in different microenvironments

Indoor environment is the place where people spend most of their time throughout their whole life. Accordingly, the assessment of exposure to particulate matter (PM) in indoor environment is crucial in order to determine the possible health effects. In this study, the number concentration of PM range from 10 nm to 10 mu m in size, deposition of PM in the respiratory tract, and the inhalation dose for the residents (dormitory, library, canteen, dining-hall, activity center, mosque, gymnasium, hospital, and classroom) were investigated. An optical particle sizer and a NanoScan scanning mobility particle sizer were used to measure the particle number concentrations in the size range of 10 nm to 300 nm and 300 nm to 10 mu m, respectively. The total number concentrations varied from 1.32 x 10(5) cm(-3) to 1.11 x 10(3) cm(-3). Deposition of particles in the respiratory system was predicted by the ICRP model. It was found that 48% of inhaled particles of 20 nm in size was the deposition in the alveolar region whereas 9.6% and 16% were in the head airway and tracheobronchial region, respectively. Maximum inhalation doses were obtained for ultrafine particles in all microenvironments. Finally, the mass deposition in the gymnasium was the highest although the particle concentration was at the last four among other microenvironments. That means physical exertion is a significant factor besides the particle concentration.