Measurements were performed in 4 classrooms in nursery
N_URB1, 3 classrooms in nursery N_URB2, and 2 classrooms in
nursery N_URB3, as well as in the lunch rooms of all nurseries.
Table 1 summarizes some of the main important characteristics for
indoor air quality in each studied room.
Indoor concentrations of the different fractions of PM (PM1,
PM2.5, PM10 and PMTotal) were continuously measured using a TSI
DustTrak DRX 8534 particle monitor using light-scattering laser
method. The minimum and maximum limit detections for this
equipment are, respectively, 0.001 mg m3 and 150 mg m3. The
equipment was submitted to a standard zero calibration (available
in the equipment) and data were validated prior to each new
measurement (in each new room). Indoor measurements were
performed from 2 to 9 days in each considered room, and, in some
cases, both in weekdays and weekends, between February and June
2013. Hourly averages were calculated from a set of four measurements
per hour (each 15 min) per day of measurement.
Simultaneously, hourly PM10 concentrations were obtained
from the nearest air quality station classified as urban traffic. These
measurements were conducted by the Air Quality Monitoring
Network of Porto Metropolitan Area, managed by the Regional
Commission of Coordination and Development of Northern
Portugal (Comissão de Coordenação e Desenvolvimento Regional do
Norte) under the responsibility of the Ministry of Environment.