Table 1 Percentiles of daily hospital emergency room visits, air pollution concentrations, weather variables and source specific PM2.5 in Helsinki, 1998–2004
Days (n)Min25%50%75%Max
Emergency room visits
    Asthma (age <15 y)2557012339
    Asthma + COPD (15–64 y)2557012312
    Asthma + COPD (⩾65 y)2557013412
Pollutants
    Nucleation mode (1/cm3)243637926734187625622790
    Aitken mode (1/cm3)2436101432594096517118830
    Ultrafine particles (1/cm3)2436914578082031154050990
    Accumulation mode (1/cm3)2436572383595252680
    PM2.5 (μg/m3)24241.15.59.511.769.5
    Coarse particles (μg/m3)23920.04.99.912.1101.4
    CO (mg/m3)25500.10.30.50.62.4
    NO2 (μg/m3)25503.420.128.234.396.4
    O3 (μg/m3)25501.649.363.076.6159.1
Weather variables
    Temperature (°C)2557−23.20.06.213.625.4
    Relative humidity (%)255738.073.080.289.099.0
    Barometric pressure (mbar)25579571005101210191052
Source specific PM2.5 (μg/m3)
    Traffic exhaust255401.21.82.37.4
    Long range transport255402.55.57.330.8
    Soil and road dust255400.51.01.210.7
    Coal/oil combustion255400.20.50.711.3
  • COPD, chronic obstructive pulmonary disease.