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. 2024 Sep 24;21(10):1263. doi: 10.3390/ijerph21101263

Figure 6.

Figure 6

Simultaneous time series of indoor/outdoor (I/O) pollutants (PNC, PM10, PM2.5, PM1, and eBC) measured at classroom A. Examples of the three different activities in the classroom considered in this study are (A) an occupancy period, (B) a window-open period during occupancy, and (C) an open-window period without occupancy. The red dotted line in PNC represents the optimal detection range of the indoor CPC (0–1 × 104 cm−3), in PM10 this dotted line represents the WHO 24 h standard of 45 µg m−3, and in PM2.5 it represents the WHO 24 h standard of 15 µg m−3 for indoor ambient air levels. In the graph, the prefix “Out” refers to outdoor, whereas “In” indicates indoor measurements.