. 2007 Feb 20;62(9):780–785. doi: 10.1136/thx.2006.076166

Table 4 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 (multipollutant model).

	NO₂ (lag 0–3)	O₃ (8 h) (lag 0–5)	SO₂ (lag 0)	PM_2.5 (lag 0–5)
4 pollutant model	0.993 (0.985 to 1.001)	1.029 (1.022 to 1.036)*†	1.008 (1.001 to 1.015)*	1.014 (1.007 to 1.022)*
3 pollutant model		1.029 (1.022 to 1.034)*†	1.008 (1.001 to 1.015)*	1.011 (1.004 to 1.017)*

SO₂, sulphur dioxide; NO₂, nitrogen dioxide; O₃, ozone; PM₁₀, PM_2.5, particulates with an aerodynamic diameter <10 μm or <2.5 μm.

*p<0.05.

†Highest χ² score in the pollutant model.

Table 4 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 (multipollutant model).