Table 1 Air pollutant levels and meteorological conditions in Copenhagen from 12 December 1998 to 19 December 2004 (2199 days)
NMean (SD)25th percentile75th percentileIQR*
    PM10 (μg/m3)174925.1 (16.7)15.730.214.5
    PM2.5† (μg/m3)4539.8 (4.5)6.811.74.9
    UFPNC‡ (particles/cm3)6028092 (3470)570698254119
    NO2 (ppb)204511.8 (5.1)
    NOx (ppb)204515.2 (8.7)9.518.48.9
    CO (ppm)20680.29 (0.10)0.220.340.12
    O3 (ppb)68025.0 (9.9)18.231.813.6
Meteorology (units)
    Temperature (°C)21439.3 (6.6)3.914.710.8
    Relative humidity (%)214275.2 (11.4)67.383.716.4
    Wind speed (m/s)20924.2 (1.5)
    Global radiation (W/m2)2128114.1 (95.5)25.5189.3163.8
  • CO, carbon monoxide; IQR, interquartile range; NOx, nitrogen oxide; NO2, nitrogen dioxide; O3, ozone; PM2.5, PM10, particulate matter <2.5 and <10 μm in diameter; UFPNC, ultrafine particles.

  • *IQR  =  75th – 25th percentile.

  • †Measurements of PM2.5 were carried out by a TEOM instrument operated at 50°C in order to dry the aerosol, resulting in loss of volatile compounds (ammonium nitrate and semivolatile organic compounds). Thus, in general TEOM measurements give smaller PM2.5 values than the gravimetric or beta-attenuation method, with a difference of 8–10 μg/m3.

  • ‡Total concentration of ultrafine particles 10–700 nm in diameter (95% of total concentration comes from particles <100 nm).