Table 2.
Summary of measured pollutant concentrations by session. Column “N” represents number of sessions while N (obs) is number of observations. The grand means of the observed concentrations, estimated background concentrations, and proportion of the mean concentration attributed to background are given in the last three columns. Numbers in parentheses represent the standard deviations of the session means.
| Pollutant | N | N (obs) | Session Mean | Background Mean | Background Fraction |
|---|---|---|---|---|---|
| BC (μg m−3) | 18 | 157107 | 1.4 (0.64) | 0.33 (0.16) | 0.27 (0.14) |
| CO (ppb) | 19 | 183693 | 270 (72) | 190 (24) | 0.74 (0.12) |
| PN (cm−3) | 18 | 173049 | 6300 (2300) | 3900 (1600) | 0.61 (0.11) |
| Ext. (Mm−1) | 15 | 150828 | 35 (13) | 27 (11) | 0.76 (0.077) |
| NO (ppb) | 19 | 183041 | 11 (7) | 1 (0.59) | 0.1 (0.043) |
| NO2 (ppb) | 19 | 181870 | 16 (7.3) | 5.2 (5) | 0.28 (0.14) |
| NOy (ppb) | 18 | 181120 | 23 (12) | 5.5 (2.5) | 0.25 (0.068) |
| Acetaldehyde (ppb) | 17 | 189208 | 2.2 (0.36) | 1.5 (0.3) | 0.68 (0.075) |
| Benzene (ppb) | 17 | 189208 | 0.51 (0.073) | 0.26 (0.057) | 0.51 (0.095) |
| Toluene (ppb) | 17 | 189208 | 0.48 (0.18) | 0.13 (0.032) | 0.28 (0.081) |