Median (range) of environmental variables for the winter (13 January–10 March 1997) and summer (19 May–14 July 1997) monitoring periods
| Environmental variable | Winter | Summer |
|---|---|---|
| Levels indicate the 24 hour mean unless indicated otherwise and pollutant data averaged across up to five sites. | ||
| *Median of days where levels exceeded the detectable limit, but most days (39/56 winter and 47/56 summer) were below this limit of approximately 5 ng/m3. | ||
| NO2 (ppb) | 18.0 (4–35) | 13.3 (3–29) |
| Ozone (ppb) | 13.0 (2–33) | 22.0 (10–41) |
| PM10 (μg/m3) | 21.5 (8–46) | 18.7 (7–38) |
| PM2.5 (μg/m3) | 12.7 (4–37) | 12.3 (5–28) |
| SO2 (ppb) | 5.4 (2–18) | 4.7 (2–10) |
| H+ (ng/m3) | 8.6 (≤12.7)* | 6.3 (≤7.6)* |
| Cl− (μg/m3) | 3.0 (0.9–7.3) | 0.8 (0.3–5.1) |
| HCl (μg/m3) | 0.3 (0.0–1.7) | 0.3 (0.0–1.0) |
| HNO3 (μg/m3) | 0.5 (0.2–2.2) | 1.1 (0.4–3.8) |
| NH3 (μg/m3) | 5.6 (0.9–23.8) | 4.2 (0.6–8.8) |
| NH4+ (μg/m3) | 2.0 (0.2–15.5) | 2.5 (0.5–7.1) |
| NO3− (μg/m3) | 3.6 (0.1–29.9) | 3.5 (0.7–13.2) |
| SO42– (μg/m3) | 2.4 (0.8–14.9) | 3.8 (1.1–7.8) |
| Minimum temperature (°C) | 2.5 (–3.5–8.1) | 9.4 (2.1–14.1) |
| Mean temperature (°C) | 5.5 (–1.0–9.9) | 13.4 (8.1–19.1) |
| Maximum temperature (°C) | 8.6 (1.5–13.3) | 17.9 (10.6–25.5) |
| Relative humidity (%) | 84 (67–96) | 74 (47–92) |
| Barometric pressure (hPa/mb) | 956 (923–977) | 952 (926–966) |
| Wind speed (mph) | 8 (2–18) | 6 (3–15) |