There was occasionally an increase of PM concentrations at the
end of the afternoon, which was kept even after the end of classroom
occupancy, mainly due to cleaning activities. Fromme et al.
(2005) also reported that cleaning activities could contribute to
the increase of PM in the indoor air. To minimize this contribution,
cleaning activities in nurseries should be performed when children
go home and with high ventilation rates to outdoor.
above the limits recommended by WHO, which is concerning in
terms of exposure effects on children’s health. The classrooms
occupied by older children were found to be those with the highest
PM concentrations, due to their higher mobility when compared
with younger ones, thus increasing PM re-suspension. Results
allowed concluding that indoor sources were clearly the main
contributors to indoor PM concentrations when compared with
outdoor influence. Due to that, the poor ventilation to outdoors in
classrooms affected indoor air quality by increasing the PM accumulation.
Results also confirmed that cleaning activities increased
PM concentrations in indoor air and suggested that cooking activities
could increase PM concentrations in lunch rooms. To improve
the air renovation rate (higher and better ventilation), as well as to
do the cleaning activities after the occupancy period could be good
practices to reduce PM indoor air concentrations in nurseries and,
consequently, improve children’s health and welfare.
For the future, it could be important to study other nurseries to
help supporting these findings, not only in urban traffic influence
context, but also in other contexts, like urban background and rural.
In next studies it could be important to determine the particulate
matter composition (heavy metals, PAH’s). Measurements of the air
flow rates could also be important to refine the analysis on the
occupancy and air renovation rates. It could also be important to
study the association of PM air pollution in these nurseries with
children’s daily exposure. Further investigations at home and in
other microenvironments occupied by children are needed to understand
if there is, or not, an increased risk of adverse health effects
on children attending nurseries when compared with those
cared at home.