Overall, PM concentrations on nurseries were found to be much
higher during occupancy periods than during non-occupancy periods
and weekends and almost constant on the latter ones, which
was consistent with the presence of children and their activities,
even in lunch rooms. However, PM10 mean levels in all studied
rooms were below mean level obtained by Yang et al. (2009) in
Korean nurseries (94.94 mg m3). This means that the presence of
children and their activities in nurseries’ microenvironments
potentiated, in general, the suspension and/or re-suspension phenomena
of PM indoors, mainly coarser fractions, which was also
found by Parker et al. (2008) for school buildings. In general, occupancy
increases PM concentrations indoors (Sousa et al., 2012b).