Table 7. Mean pollutant concentrations by year and difference in pollutant concentration from post-tunnel year compared to pre-tunnel year.
| Site & pollutant | Mean pollutant levels (SD) | Difference in pollutant levelsa | ||
| Pre-tunnel yeara | First post-tunnel yearb | Unadjusted estimate (95% CI) | Adjusted estimate (95% CI)c | |
| Elevated site near eastern ventilation stack | ||||
| NO2 ppb | 16.7 (7.0) | 15.7 (5.3) | −2.55 (−4.43, −0.66) | −1.00 (−2.21, 0.22) |
| NOx ppb | 30.7 (17.8) | 27.1 (14.1) | −6.33 (−10.97, −1.70) | −2.10 (−3.84, −0.37) |
| PM10 µg/m3 | 20.2 (8.1) | 16.1 (6.8) | −4.02 (−6.24, −1.80) | −1.74 (−3.04, −0.43) |
| PM2.5 µg/m3 | 6.4 (3.6) | 5.3 (3.2) | −1.13 (−2.38, 0.12) | −0.26 (−0.65, 0.12) |
| Elevated site near western ventilation stack | ||||
| NO2 ppb | 13.4 (5.6) | 12.1 (4.5) | −1.96 (−3.08, −0.84) | −1.07 (−1.68, −0.45) |
| NOx ppb | 26.1 (19.9) | 20.6 (14.6) | −6.05 (−10.47, −1.62) | −2.79 (−4.46, −1.11) |
| PM10 µg/m3 | 18.7 (7.4) | 16.2 (7.0) | −2.39 (−4.22, −0.56) | −0.46 (−1.94, 1.03) |
| PM2.5 µg/m3 | 6.2 (3.5) | 5.3 (3.3) | −1.02 (−1.98, −0.06) | −0.19 (−0.65, 0.27) |
a
Difference between pre-tunnel and first post-tunnel years, estimated by autoregressive analysis.
b
Pre-tunnel is 25 March 06–24 March 07 and first post-tunnel year is 25 March 2007–24 March 2008.
Data for only one post-tunnel year available.
c
Adjusted for change in air quality at the three Sydney regional sites (averaged).