Table 6

Incident chronic bronchitis and chronic cough at second assessment, per IQR increase in each pollutant

Adjusted* OR (95% CI)
Cases/non-cases (n/n)PM2.5 NO2 Black carbon
All participants
 Chronic bronchitis2946/62 0631.01 (0.96 to 1.06) 1.07 (1.02 to 1.13) 1.07 (1.02 to 1.13)
 Chronic cough3956/61 0221.01 (0.96 to 1.05)1.03 (0.98 to 1.08)1.03 (0.99 to 1.08)
Females
 Chronic bronchitis1479/37 2051.03 (0.96 to 1.10) 1.11 (1.03 to 1.20) 1.10 (1.02 to 1.17)
 Chronic cough2099/36 5631.03 (0.97 to 1.09)1.07 (1.00 to 1.14)1.05 (0.99 to 1.12)
Age >=50
 Chronic bronchitis1229/21 6190.97 (0.91 to 1.03)1.02 (0.95 to 1.10)1.05 (0.98 to 1.12)
 Chronic cough1645/21 1860.99 (0.93 to 1.04)1.02 (0.96 to 1.09)1.03 (0.97 to 1.09)
No post-secondary education
 Chronic bronchitis2233/42 3891.01 (0.96 to 1.07) 1.08 (1.01 to 1.15) 1.08 (1.02 to 1.15)
 Chronic cough2996/41 6011.01 (0.97 to 1.06)1.04 (0.99 to 1.11)1.05 (1.00 to 1.11)
Never smokers
 Chronic bronchitis1090/30 4521.04 (0.96 to 1.12) 1.14 (1.05 to 1.25) 1.14 (1.06 to 1.23)
 Chronic cough1507/30 0211.04 (0.97 to 1.11) 1.11 (1.03 to 1.19) 1.08 (1.01 to 1.16)
Asthmatics
 Chronic bronchitis418/40351.05 (0.92 to 1.20)1.09 (0.94 to 1.27)1.11 (0.97 to 1.27)
 Chronic cough462/39900.98 (0.86 to 1.12)1.08 (0.93 to 1.25)1.06 (0.93 to 1.21)
  • Statistically significant results are shown in bold.

  • *Model adjusted for sex, age, educational attainment (low: junior secondary/lower vocational or less, medium: senior secondary/secondary vocational, high: higher vocational/university), BMI (continuous), smoking status (never, ex, current), pack-years smoking, environmental tobacco smoke at home and follow-up time.

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