Descriptive statistics for the four air pollutant annual mean concentrations and the composite index across all wards
| Air quality variable | Mean | Standard deviation | Minimum | Maximum |
|---|---|---|---|---|
| Benzene (ppb) | 0.56 | 0.43 | 0.08 | 2.63 |
| PM10 (μg/m3) | 23.95 | 3.58 | 17.87 | 41.37 |
| SO2 (ppb) | 3.71 | 1.99 | 1.15 | 31.32 |
| NO2 (ppb) | 12.42 | 6.15 | 2.63 | 42.51 |
| Combined index | 1.50 | 0.53 | 0.68 | 3.96 |