Table 3

 Relative risk (with 95% CI) for the pollutants per 10 μg/m3 increase in the concentration of air pollutants for hospitalisations due to an acute exacerbation of COPD (single pollutant model)

Lag daysNO2PM10O3 (8 h)SO2PM2.5
SO2, sulphur dioxide; NO2, nitrogen dioxide; O3, ozone; PM10, PM2.5, particulates with an aerodynamic diameter <10 μm or <2.5 μm.
*p<0.05, **p<0.001.
†Highest χ2 score (best lag).
Lag 01.009 (1.005 to 1.013)**1.003 (1.000 to 1.005)*1.002 (0.998 to 1.005)1.007 (1.001 to 1.014)*†1.002 (0.998 to 1.001)
Lag 11.001 (0.997 to 1.005)1.005 (1.002 to 1.007)**1.011 (1.008 to 1.015)**0.991 (0.981 to 1.001)1.003 (0.999 to 1.007)**
Lag 21.003 (0.999 to 1.007)1.010 (1.007 to 1.012)**1.011 (1.008 to 1.020)**0.992 (0.985 to 1.000)1.011 (1.007 to 1.014)**
Lag 31.010 (1.007 to 1.014)**1.011 (1.008 to 1.013)**1.011 (1.012 to 1.019)**1.006 (0.999 to 1.013)1.013 (1.010 to 1.017)**
Lag 41.010 (1.007 to 1.014)**1.008 (1.006 to 1.011)**1.011 (1.008 to 1.015)**1.004 (0.998 to 1.011)1.011 (1.008 to 1.015)**
Lag 51.008 (1.004 to 1.012)**1.007 (1.004 to 1.009)**1.006 (1.003 to 1.010)**1.004 (0.997 to 1.010)1.009 (1.006 to 1.013)**
Lag 0–11.007 (1.003 to 1.011)**1.005 (1.002 to 1008)**1.011 (1.006 to 1.014)**0.998 (0.991 to 1.006)1.004 (0.999 to 1.008)
Lag 0–21.009 (1.004 to 1.013)**1.011 (1.008 to 1.014)**1.019 (1.015 to 1.023)**0.993 (0.985 to 1.001)1.010 (1.006 to 1.015)**
Lag 0–31.026 (1.022 to 1.031)**†1.016 (1.013 to 1.019)**1.027 (1.02 to 1.031)**0.998 (0.989 to 1.007)1.018 (1.013 to 1.022)**
Lag 0–41.021 (1.017 to 1.026)**1.020 (1.017 to 1.024)1.031 (1.027 to 1.036)**1.001 (0.991 to 1.010)1.024 (1.019 to 1.029)**
Lag 0–51.026 (1.022 to 1.031)**1.024 (1.021 to 1.028)**†1.034 (1.030 to 1.040)**†1.004 (0.994 to 1.014)1.031 (1.026 to 1.036)**†