| 
      
        |  | Fall | Winter | Spring | Summer | p |  
        | Mean    PM10level (mg/m3) | 54.1±26.8 | 82.7±40.9 | 38.7±25.0 | 42.1±18.9 | <0.001 |  
        | Mean    SO2 level (mg/m3) | 9.8±9.3 | 45.5±25.0 | 13.2±7.3 | 5.0±2.7 | <0.001 |  
        | Mean    daily temperature (ºC) | 19.2±5.1 | 8.5±3.0 | 18.0±4.0 | 28.1±2.3 | <0.001 |  
        | Mean    daily relative humidity (%) | 60.9±12.7 | 63.9±10.7 | 55.5±11.2 | 43.5±9.3 | <0.001 |  
        | Mean    actual air pressure (hPa) | 1012.0±6.0 | 1018.5±7.3 | 1009.5±3.6 | 1005.8±2.3 | <0.001 |  
        | Mean sea level air pressure    (hPa) | 1015.7±4.6 | 1022.6±6.1 | 1012.4±5.4 | 1008.8±2.6 | <0.001 |  |