indoor pm2.5 concentrations in the office, café, and home

since individuals spend the majority of their times indoors, fine particles generated in indoor combustion processes and by resuspension are important for health effects assessment. the nature and magnitude of indoor particle exposures can change rapidly because of the rapid changes in activities and sources. indoor pm 2.5 concentrations were measured in indoor office, café, and home where people spend majority of their time in there. a real time monitor was used to provide a high degree of resolution for investigating temporal patterns in particle concentrations. the average pm 2.5 concentration obtained from the direct reading compared with the mean pm 2.5 concentrations that are obtained by gravimetric measurements during the same continuous sampling. mean pm 2.5 concentrations in the big office were more than twice as high as those measured in the small quiet office (19.8 and 7.3 respectively). in the home, cooking increased pm 2.5 concentration. the highest particle concentrations in home (average 28 µg m -3 ) were related to a period around midnight when there were a larger number of occupants inside the living room. mean pm 2.5 concentrations measured in the smoking area of the café were much higher than those measured in the non-smoking area (50.0 and 17.6 µg m -3 respectively). outdoor air pollution can affect the indoor particulate concentration when the indoor source not exists. smoking, cooking, and resuspension of indoor particulate matter are the most important sources for indoor particle concentrations.