Correlation* between CO, BS, NO, and NO2 concentrations obtained in the taxis, and concentrations recorded at the Paris air monitoring network fixed stations
| Correlation between taxis and urban background sites (r ) | p Value | Correlation between taxis and close to traffic sites (r) | p Value | Correlation between taxis and heavy traffic sites (r) | p Value | |
| CO | 0.69 | =0.001 | 0.57 | <0.001 | 0.71 | =0.001 |
| BS | 0.55 | =0.002 | 0.34 | =0.055 | 0.40 | =0.03 |
| NO | 0.62 | =0.001 | 0.31 | >0.05 | 0.42 | =0.02 |
| NO2 | 0.25 | >0.05 | 0.16 | >0.05 | 0.22 | >0.05 |
r=Pearson correlation coefficient.