According to the results shown above, HCHO, acetaldehyde and TVOCs were kept in safe and acceptable levels
in the classrooms; but indoor PM pollution was at a severe situation, especially in winter, due to the high ambient
PM pollution. As shown in previous publication (GB3095-2012), the children are suffering from “heavily polluted”
or “severely polluted” environments either indoors or outdoors.
In our study, the indoor/outdoor (I/O) ratio of PM2.5 varied in the rage of 0.84–1.23 in autumn and 0.86-0.95 in
winter. The high I/O ratio suggested that most of the fine particles in the naturally ventilated indoor spaces were
from outdoor air. Furthermore, PM1.0 indicated to be the primary component of PM10 as the ratio of PM1.0 to PM10
was up to 0.71-0.86 in autumn and 0.78-0.86 in winter.