Table 3

Baseline air pollution concentrations descriptive statistics

Mean (SD)MinMaxIQRnPearson correlation coefficients (95% CI)
PM2.5 NO2 Black carbon
PM2.5 (µg/m3)14.8 (1.02)9.3521.81.30135 2261.0000.565 (0.561 to 0.568)0.480 (0.476 to 0.484)
NO2 (µg/m3)21.5 (4.99)9.0765.46.92135 2261.0000.889 (0.888 to 0.890)
Black carbon (10−5 m−1)1.22 (0.23)0.653.150.29135 2261.000
  • For participants with complete data for chronic bronchitis, sex, age, educational attainment, BMI, smoking status, pack-years smoking, environmental tobacco smoke at home.

  • BMI, body mass index; NO2, nitrogen dioxide; PM2.5, particulate matter with a diameter of less than 2.5 µm.