Figs. 3e7 show the average daily profiles of PM1, PM2.5, PM10 and
PMTotal, respectively (a) to (d), for N_URB1 and N_URB2 during
weekdays and weekends (respectively Figs. 3e6) and N_URB3
during weekdays and weekends (Fig. 7). Table 2 summarizes the
statistical parameters (minimum, maximum, mean and median) of
the hourly means for each room studied in the three nurseries.
Figs. 3, 5 and 7 showed that PM concentrations in the classrooms
started to rise up at the beginning of the occupancy period
and started decreasing after the end of the occupancy period (time
variable, depending on the room). Figs. 4, 6 and 7 showed that the
concentrations during weekends and non-occupancy periods did
not seem to have high fluctuations neither peaks, thus being
considered background concentrations for each respective room.
The highest PM1 and PM2.5 concentrations were registered in
N_URB2 (classroom C), while the highest PM10 and PMTotal concentrations
were found in N_URB1 (classroom C). The minimum
concentrations of all PM fractions were observed in the LR of
N_URB1. Likewise, the minima concentrations in N_URB3 were
observed in the LR; nevertheless, in N_URB2, the LR had higher
concentrations than the other measured rooms. Minima concentrations
were always found during weekends or periods of nonoccupancy
and maxima concentrations were always registered
during occupancy periods, as can be observed on Figs. 3e7. Table 2
showed that median values were very close to mean values, so
there was not great scattering in the measurements in each room.