New approach for particulate exposure monitoring: determination of inhaled particulate mass by 24 h real-time personal exposure monitoring

The objectives of this study were to measure particulate pollution (PM10, PM2.5, and PM1.0) continuously (24 h/day for 7 day) using real-time exposure monitoring and to estimate total inhalation mass using breathing rate and time-activity. Breathing rates were calculated from measured heart rates. Participants were asked to record a time-activity diary every 15 min. Five microenvironments were defined based on the time-activity diary: home, workplace/school, other indoor, outdoor, and transportation. The average masses of inhaled PM10 were 530, 316, and 280 mu g/day for two office workers, a housewife, and three students, respectively; those of PM2.5 were 316, 279, and 210 mu g/day; and those of PM1.0 were 251, 264, and 187 mu g/day, respectively. We found that home and office/school microenvironments were the main contributors of PM10, PM2.5, and PM1.0 inhaled mass during weekdays and weekends because dwelling time was a determinant factor for inhaled mass. Considering microenvironmental concentration, breathing rate, and dwelling time in each microenvironment, indoor home microenvironments were the largest source of particulate inhalation, followed in order by workplace, transportation, other indoor, and outdoor microenvironments. 34.6% and 69.6% of PM10 inhalation mass were accumulated in home microenvironments during weekdays and weekends, respectively. The inhaled mass of particulate <1.0 mu m (PM1.0) in size occupied largest, followed in order by particulate 10-2.5 mu m (coarse particle) and 2.5-1.0 mu m in size for all occupations.