Table 2
Descriptive statistics for study pollutants and weather variables
| Variables | Mean | Median | IQR |
|---|---|---|---|
| Daily mean pollutant* | |||
PM2.5  | 15.3 | 12.9 | 10.1–18.0 |
PM10  | 24.8 | 21.6 | 17.2–28.9 |
O3  | 36.8 | 36.4 | 23.2–49.3 |
NO2  | 44.6 | 42.8 | 33.6–53.6 |
NOX  | 78.9 | 67.0 | 50.5–92.4 |
| Weather | |||
| Daily mean temperature (°C)† | 11.5 | 11.7 | 7.5–15.9 |
| Daily mean relative humidity (%)† | 76.0 | 77.0 | 68.5–84.2 |
*Descriptive statistics based on daily data for 2005–2012 for all 1372 study postcodes (n=3 921 995).
†Descriptive statistics based on daily data for 2005–2012 (ie, unlike the pollution data, the weather data were not postcode specific; n=2921).
NO2, nitrogen dioxide; NOX, NO2+nitrogen oxide; O3, ozone; PM10, particulate matter <10 µm in diameter; PM2.5, particulate matter <2.5 µm in diameter.