Table 5– Pooled results: association between particulate matter with a 50% cut-off aerodynamic diameter of 10 μm^#, and natural or respiratory mortality^¶ from models adjusted for nitrogen dioxide (NO₂) and ozone (O₃) in 10 Italian cities

	Increased risk % (95% CI)	p-value⁺
Natural mortality
Single-pollutant model	0.80 (0.41–1.19)	0.246
Model with NO₂	0.32 (-0.08–0.73)	0.363
Single-pollutant model^§	2.05 (1.27–2.85)	0.089
Model with O₃^§	2.13 (1.34–2.92)	0.230
Respiratory mortality
Single-pollutant model	2.29 (1.03–3.58)	0.311
Model with NO₂	2.23 (0.58–3.90)	0.512
Single-pollutant model^§	7.49 (2.17–13.08)	0.006
Model with O₃^§	7.45 (2.17–13.00)	0.013

Data shown are for the study period 2001–2005. ^#: measured as 10-μg·m⁻³ increase in concentration; ^¶: from unconstrained distributed lag models, using 0–2 days for natural-cause mortality and 0–3 days for respiratory-cause mortality; ⁺: heterogeneity test (null hypothesis is perfect homogeneity of city-specific results); ^§: April to September.