Table 1 Environmental variables and number of deaths (age 65+ years) in the four Italian cities
Bologna (2000–3)Milan (1999–2003)Rome (1998–2004)Turin (1997–2003)
Environmental variables
Apparent temperature (°C)
        Mean (SD)13.8 (10.0)14.3 (10.4)15.7 (8.6)11.9 (9.4)
        Min−5.8−6.1−2.8−6.0
        Max33.937.533.333.2
    Percentiles
        25th5.05.48.43.7
        50th13.313.615.411.2
        75th22.123.122.819.8
Difference of apparent temperature between “case-day” and “control-days” (°C)
        Mean (SD)0.2 (4.8)0.1 (4.8)0.1 (4.5)0.1 (4.8)
        Min−21.1−23.6−16.6−20.9
        Max21.123.616.620.9
    Percentiles
        25th−3.0−3.0−2.8−3.0
        50th0.20.10.10.1
        75th3.33.33.03.2
Barometric pressure (hPa)
        Mean (SD)1016 (7.4)1016 (7.4)1015 (6.6)1017 (7.6)
PM10 (μg/m3)
        Mean (SD)50.4 (31.7)56.7 (37.4)47.3 (19.8)65.5 (34.8)
Ozone (μg/m3) (April to September)
        Mean (SD)102.2 (35.9)117.4 (42.6)110.8 (30.5)100.8 (39.0)
Population under study
No of deaths (%), age 65+ years14 838 (100.0)45 818 (100.0)123 484 (100.0)44 456 (100.0)
Location of death
        Nursing home6868 (15.0)3173 (7.1)
        Out of hospital6105 (41.1)18 354 (40.1)59 524 (48.2)12 468 (28.1)
        In hospital (<2 days)2870 (19.4)4422 (9.6)10 937 (8.9)8926 (20.1)
        In hospital (⩾2 days)5858 (39.5)16 174 (35.3)53 023 (42.9)19 889 (44.7)