# Assessment of Daily Personal PM2.5 Exposure Level According to Four Major Activities among Children
## 4 Discussion  
This study was conducted to evaluate real-time (10 s interval) personal exposure levels to PM2.5 by four activity patterns among 15 children. We demonstrated that our personal monitoring technologies and incorporation methodologies of various databases were potentially effective to obtain spatial-temporal distributions of PM2.5 per activity and find person-specific possible exposure sources. In our study, daily median PM2.5 exposure concentrations by activity were similar to each other (commuting with parents' car: 10.9 \(\mu\)g/m\({}^{3}\); spending time inside a commercial building: 9.6 \(\mu\)g/m\({}^{3}\); spending time inside an education building (elementary school, kinder-garden, nursery etc. ): 11.0 \(\mu\)g/m\({}^{3}\); and spending time inside home without cooking: 9.6 \(\mu\)g/m\({}^{3}\)). However, these values were lower than a previous study conducted by [PERSON] et al. (19 \(\mu\)g/m\({}^{3}\)) [19] or the WHO 24-h exposure guidelines (25 \(\mu\)g/m\({}^{3}\)). However, we found that depending on the person, the individual daily exposure concentration was close to the acute WHO exposure guidelines. According to Table 2 and Figure 3, our time-activity pattern records showed that children spent \(72.7\pm 18.7\%\) of their time inside home and they inhaled 57.7% of the daily total accumulated amount (dose) of PM2.5. Children spent \(27.2\pm 14.4\%\) of their time in education institutes and inhaled 28.1% of the daily total dose. Spending time in commercial buildings or commuting cars accounted for \(11.5\pm 9.6\) or \(5.3\pm 5.9\%\) of the daily total exposure duration and children inhaled 9.0 or 5.2% of their daily total dose there. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{ID} & \multicolumn{4}{c}{**Car**} & \multicolumn{4}{c}{**Commercial Building**} & \multicolumn{4}{c}{**Education Building**} & \multicolumn{4}{c}{**Indoor-House**} \\ \cline{2-13}  & **N** & **(Data)** & **25\%** & **50\%** & **75\%** & **(Data)** & **25\%** & **50\%** & **75\%** & **N** & **(Data)** & **25\%** & **50\%** & **75\%** & **N** & **(Data)** & **25\%** & **50\%** & **75\%** \\ \hline ID\_001 & 2 & 4.9 & 8.2 & 11.5 & 6 & 8.3 & 15.4 & 21.4 & 4 & 45.0 & 53.3 & 55.7 & 7 & 54.4 & 84.6 & 135.0 \\ ID\_002 & 1 & 9.8 & 9.8 & 9.8 & 3 & 4.0 & 4.2 & 19.6 & 2 & 40.5 & 55.3 & 70.2 & 6 & 58.8 & 63.0 & 78.3 \\ ID\_003 & NA & – & – & – & 1 & 20.3 & 20.3 & 20.3 & 1 & 561.7 & 561.7 & 561.7 & 3 & 92.8 & 142.7 & 259.2 \\ ID\_004 & 1 & 3.1 & 3.1 & 3.1 & 3.1 & 3 & 17.7 & 29.4 & 29.6 & 4 & 38.9 & 43.0 & 64.2 & 5 & 152.1 & 155.7 & 166.2 \\ ID\_005 & NA & – & – & – & 3 & 7.0 & 8.1 & 13.6 & 3 & 20.8 & 21.6 & 23.6 & 3 & 35.9 & 42.3 & 44.9 \\ ID\_006 & 2 & 4.5 & 8.1 & 11.8 & 4 & 3.8 & 7.8 & 12.8 & 5 & 23.3 & 38.7 & 81.7 & 7 & 103.7 & 158.9 & 219.0 \\ ID\_007 & 1 & 2.9 & 2.9 & 2.9 & 1 & 53.1 & 53.1 & 53.1 & 4 & 21.4 & 24.5 & 30.1 & 5 & 58.6 & 68.6 & 87.0 \\ ID\_008 & 1 & 0.4 & 0.4 & 0.4 & 2 & 5.5 & 7.4 & 9.2 & 4 & 12.8 & 18.4 & 32.3 & 6 & 57.5 & 73.5 & 87.8 \\ ID\_009 & 1 & 3.6 & 3.6 & 3.6 & 5 & 18.4 & 18.5 & 26.2 & 5 & 30.2 & 42.4 & 68.9 & 5 & 88.6 & 91.2 & 102.0 \\ ID\_010 & NA & – & – & – & 2 & 13.3 & 16.3 & 19.2 & NA & – & – & – & 4 & 45.5 & 69.1 & 90.5 \\ ID\_011 & 7 & 8.4 & 11.5 & 12.4 & NA & – & – & – & 8 & 46.0 & 47.2 & 48.5 & 8 & 154.3 & 170.7 & 189.0 \\ ID\_012 & 6 & 6.5 & 7.5 & 8.5 & 3 & 7.4 & 11.4 & 12.7 & 3 & 101.5 & 148.7 & 189.4 & 7 & 107.8 & 160.5 & 205.6 \\ ID\_013 & 3 & 2.7 & 4.4 & 4.6 & 1 & 32.1 & 32.1 & 32.1 & NA & – & – & – & 3 & 87.8 & 143.2 & 158.3 \\ ID\_014 & 4 & 15.2 & 31.0 & 48.7 & 4 & 18.4 & 31.9 & 77.6 & NA & – & – & – & 6 & 56.5 & 67.7 & 112.3 \\ ID\_015 & 3 & 5.3 & 7.9 & 9.2 & 3 & 6.4 & 9.0 & 9.4 & 2 & 16.7 & 28.8 & 41.0 & 4 & 63.9 & 82.7 & 106.3 \\ Total & 32 & 3.5 & 8.0 & 13.2 & 41 & 5.9 & 13.9 & 23.4 & 45 & 22.9 & 43.3 & 55.6 & 79 & 55.9 & 88.9 & 159.7 \\ \hline \hline \end{tabular}  
NA: not available.  
\end{table} 
Table 4: Percentiles of daily accumulated PM2.5 exposure amount (\(\mu\)g) per activity and per person.