Never-smokers at the most recent assessment*: fixed-effect meta-analysis results on model 3 (adjusted for age, sex, smoking, education and season of interview) for all air pollutants and traffic indicators for each outcome, using ESCAPE-period (2008–2011) exposures from all five cohorts
| Outcome | Chronic bronchitis | Chronic cough | Chronic phlegm | |||
|---|---|---|---|---|---|---|
| Exposure‡ | OR | phet§ | OR | phet | OR | phet |
| (95% CI) | (95% CI) | (95% CI) | ||||
| PM2.5 (5 µg/m3) | 1.28 | 0.488 | 1.11 | 0.091 | 1.16 | 0.519 |
| (0.95 to 1.72) | (0.90 to 1.36) | (0.91 to 1.48) | ||||
| PM2.5abs (per 10−5 m−1) | 1.20 | 0.233 | 1.16 | 0.032 | 1.10 | 0.602 |
| (0.92 to 1.57) | (0.96 to 1.39) | (0.87 to 1.39) | ||||
| 1.27† (0.88 to 1.85) | ||||||
| PM10 (10 µg/m3) | 1.35 | 0.763 | 1.08 | 0.535 | 1.32 | 0.474 |
| (0.97 to 1.88) | (0.86 to 1.35) | (1.02 to 1.71) | ||||
| PMcoarse (5 µg/m3) | 1.15 | 0.979 | 1.06 | 0.954 | 1.31 | 0.457 |
| (0.87 to 1.53) | (0.87 to 1.29) | (1.05 to 1.64) | ||||
| NO2 (10 µg/m3) | 1.06 | 0.440 | 1.04 | 0.088 | 1.02 | 0.234 |
| (0.93 to 1.20) | (0.97 to 1.12) | (0.92 to 1.13) | ||||
| NOx (20 µg/m3) | 1.09 | 0.151 | 1.04 | 0.021 | 1.05 | 0.121 |
| (0.93 to 1.28) | (0.97 to 1.12) | (0.96 to 1.15) | ||||
| 1.06† (0.91 to 1.23) | ||||||
| Traffic intensity¶ | 1.12 | 0.763 | 1.07 | 0.629 | 1.04 | 0.830 |
| (0.79 to 1.57) | (0.84 to 1.37) | (0.80 to 1.37) | ||||
| Traffic load** | 1.11 | 0.354 | 1.03 | 0.51 | 1.02 | 0.422 |
| (0.83 to 1.49) | (0.82 to 1.29) | (0.79 to 1.32) | ||||
Bold type denotes statistical significance, p <0.05. *Asthma-E3N 2011, ECRHS 1998–2002, NSHD 2008, SALIA 2006–10, SAPALDIA 2002. Due to questionnaire wording SALIA (>70% never-smokers) is not included in analyses of phlegm alone.
†Estimates from random-effect meta-analysis as Phet: <0.05.
‡Results were interpreted as per exposure unit, as shown in the parentheses.
§Phet: P-value for heterogeneity.
¶Binary variable, <5000 (reference group) vs >5000 vehs/day.
**Binary variable, <500 000 (reference group) vs >500 000 vehs m/day.
ECRHS, European Community Respiratory Health Survey; ESCAPE, European Study of Cohorts for Air Pollution Effects; NOx; nitrogen oxides; NSHD, National Survey of Health and Development; PM, particulate matter; SALIA, Study on the influence of Air pollution on Lung function, Inflammation and Aging; SAPALDIA, Swiss cohort study on Air Pollution And Lung and heart Diseases in Adults.