Correlation among air pollutants (CO, NOx, O3, PM10, PM2.5, SO2, and PM10−2.5) using Spearman’s analysis
| Pollutants | CO | NOx | O3 | PM10 | PM2.5 | SO2 | PM10−2.5 |
| CO | 1.000 | 0.945* | −0.570* | 0.040* | 0.068* | 0.196* | −0.004* |
| NOx | – | 1.000 | −0.547* | 0.057* | 0.105* | 0.232* | −0.017* |
| O3 | – | – | 1.000 | 0.249* | 0.141* | −0.083* | 0.307* |
| PM10 | – | – | – | 1.000 | 0.892* | 0.495* | 0.843* |
| PM2.5 | – | – | – | – | 1.000 | 0.418* | 0.508* |
| SO2 | – | – | – | – | – | 1.000 | 0.446* |
| PM10−2.5† | – | – | – | – | – | – | 1.000 |
CO, carbon monoxide; NOx, nitrogen oxides; O3, ozone; PM, particulate matter; SO2, sulfur dioxide.
*P < 0.05.
†PM10minus PM2.5.