Air pollution data
Ambient air pollution data were supplied by the Environment
Canada [11]. In this study we considered ozone (O3
),
carbon monoxide (CO), nitrogen dioxide (NO2
), sulphur
dioxide (SO2
), and 2 kinds of particulate matter (of median
aerodynamic diameter no greater than 2.5 μm (PM2.5)
and 10 μm (PM10)). The daily mean of a pollutant was defined
locally as an average of its 24 hourly readings recorded
by a local pollution monitoring station. Daily ambient
exposure was represented by the average of daily means
across 3 monitoring stations that were in operation in Edmonton
during the study time interval [12]. The maximum
distance between the stations was 11 km. Lagging was applied
to the daily ambient exposure to the individual pollutants
(lags 0–9 days)