Contrasts* in lung function, eNO and symptom scores between the downwind site and the other two sites (upwind and heavily trafficked) adjusted for change from baseline (2006) to subsequent years
| Contrast* | FEV1 (diff in litres) (95% CI) | FVC (diff in litres) (95% CI) | eNO ratio (95% CI) | EYE symptoms (diff in score) (95% CI) | THROAT symptoms (diff in score) (95% CI) | |
|---|---|---|---|---|---|---|
| Location | Year | |||||
| Downwind versus (heavily trafficked and upwind)† | 2007/2008 vs 2006‡ | 0.01 (−0.04 to 0.06) | 0.03 (−0.03 to 0.09) | 1.03 (0.94 to 1.12) | −0.006 (−0.097 to 0.086) | 0.130 (−0.084–0.344) |
| 2007 vs 2006 | 0.03 (−0.03 to 0.09) | 0.05 (−0.03 to 0.13) | 1.01 (0.91 to 1.11) | −0.055 (−0.159 to 0.049) | 0.041 (−0.220–0.301) | |
| 2008 vs 2006 | −0.004 (−0.07 to 0.06) | 0.02 (−0.07 to 0.10) | 1.05 (0.94 to 1.17) | 0.043 (−0.074 to 0.159) | 0.207 (−0.027 to 0.441) | |
| Downwind versus upwind | 2007/2008 vs 2006‡ | 0.02 (−0.04 to 0.08) | 0.06 (−0.02 to 0.13) | 1.03 (0.93 to 1.14) | −0.044 (−0.151 to 0.063) | 0.080 (−0.169 to 0.329) |
| 2007 vs 2006 | 0.04 (−0.03 to 0.11) | 0.06 (−0.03 to 0.15) | 1.05 (0.94 to 1.17) | −0.108 (−0.229 to 0.012) | −0.006 (−0.308 to 0.297) | |
| 2008 vs 2006 | 0.004 (−0.07 to 0.08) | 0.06 (−0.04 to 0.15) | 1.01 (0.89 to 1.15) | 0.015 (−0.120 to 0.149) | 0.179 (−0.092 to 0.449) | |
| Downwind versus heavily trafficked | 2007/2008 vs 2006‡ | −0.00 (−0.06 to 0.06) | 0.004 (−0.07 to 0.08) | 1.03 (0.93 to 1.14) | 0.033 (−0.073 to 0.140) | 0.180 (−0.068 to 0.428) |
| 2007 vs 2006 | 0.02 (−0.05 to 0.09) | 0.04 (−0.05 to 0.12) | 0.97 (0.87 to 1.08) | −0.002 (−0.121 to 0.117) | 0.087 (−0.212 to 0.385) | |
| 2008 vs 2006 | −0.01 (−0.09 to 0.06) | −0.03 (−0.12 to 0.07) | 1.09 (0.96 to 1.23) | 0.071 (−0.065 to 0.206) | 0.236 (−0.038 to 0.509) | |
| Heavily trafficked versus (upwind and downwind)§ | Overall | −0.01 (−0.04 to 0.01) | −0.03 (−0.06 to 0.002) | 1.09 (1.04 to 1.14) | 0.054 (0.006 to 0.102) | 0.107 (−0.005 to 0.218) |
| Downwind versus (heavily trafficked and upwind)† | 2007/2008 vs 2006‡ | −0.080 (−0.302 to 0.142) | 0.288 (−0.139 to 0.716) | 0.276 (0.040 to 0.511) | 3.45 (1.57 to 7.60) | 1.69 (0.72 to 3.96) |
| 2007 vs 2006 | −0.031 (−0.277 to 0.214) | 0.375 (−0.093 to 0.844) | 0.320 (0.053–0.587) | 5.72 (2.35 to 13.91) | 1.95 (0.77 to 4.94) | |
| 2008 vs 2006 | −0.133 (−0.409 to 0.143) | 0.182 (−0.254 to 0.618) | 0.229 (−0.057 to 0.516) | 2.14 (0.77 to 5.97) | 1.33 (0.44 to 4.00) | |
| Downwind versus upwind | 2007/2008 vs 2006‡ | −0.017 (−0.275 to 0.242) | 0.430 (−0.067 to 0.927) | 0.193 (−0.081 to 0.466) | 3.51 (1.40 to 8.80) | 1.23 (0.45 to 3.40) |
| 2007 vs 2006 | 0.033 (−0.252 to 0.318) | 0.422 (−0.123 to 0.966) | 0.187 (−0.124 to 0.498) | 4.11 (1.48 to 11.43) | 1.12 (0.38 to 3.37) | |
| 2008 vs 2006 | −0.042 (−0.362 to 0.277) | 0.424 (–0.080 to 0.929) | 0.178 (−0.154 to 0.510) | 3.31 (0.98 to 11.18) | 1.26 (0.34 to 4.71) | |
| Downwind versus heavily trafficked | 2007/2008 vs 2006‡ | −0.143 (−0.400 to 0.114) | 0.147 (−0.349 to 0.642) | 0.358 (0.086 to 0.631) | 3.39 (1.39 to 8.29) | 2.31 (0.90 to 5.94) |
| 2007 vs 2006 | −0.096 (−0.377 to 0.185) | 0.329 (−0.208 to 0.866) | 0.453 (0.146 to 0.759) | 7.96 (2.89 to 21.93) | 3.38 (1.20 to 9.54) | |
| 2008 vs 2006 | −0.224 (−0.547 to 0.099) | −0.060 (−0.570–0.450) | 0.281 (−0.054 to 0.617) | 1.38 (0.44 to 4.40) | 1.40 (0.41 to 4.75) | |
| Heavily trafficked versus (upwind and downwind)§ | Overall | 0.209 (0.094 to 0.325) | 0.150 (−0.072 to 0.372) | 0.022 (−0.101 to 0.144) | 2.34 (1.58 to 3.49) | 4.08 (2.67 to 6.25) |
*Contrasts are derived from mixed effects regression model in which location and year, and the interaction between them are fixed effects, and individual subject intercepts are a random effect. Main contrasts of interest are those included in the table and consist of downwind versus other exposures, as the downwind exposure is the primary exposure of interest in this study.
†Downwind versus (heavily trafficked and upwind) is the comparison of downwind versus heavily trafficked and upwind exposures combined.
‡2007/2008 vs 2006 represents the comparison of both post-tunnel years combined (2007/2008) versus the pre-tunnel year (2006).
§Represents the overall comparison of the heavily trafficked site compared to the upwind and downwind sites combined (data from all years included), as we anticipated the heavily trafficked site to have higher air pollution levels and that health effects would be more prominent.
eNO, exhaled nitric oxide; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.