Background: This study aimed to assess associations of outdoor air pollution on prevalence of chronic bronchitis symptoms in adults in fi ve cohort studies (Asthma-E3N, ECRHS, NSHD, SALIA, SAPALDIA) participating in the European Study of Cohorts for Air Pollution Effects (ESCAPE) project. Methods: Annual average particulate matter (PM10, PM2.5, PMabsorbance, PMcoarse), NO2, nitrogen oxides (NOx) and road traffic measures modelled from ESCAPE measurement campaigns 2008-2011 were assigned to home address at most recent assessments (1998-2011). Symptoms examined were chronic bronchitis (cough and phlegm for ≥3 months of the year for ≥2 years), chronic cough (with/without phlegm) and chronic phlegm (with/without cough). Cohort-speci fic cross-sectional multivariable logistic regression analyses were conducted using common confounder sets (age, sex, smoking, interview season, education), followed by meta-analysis. Results: 15 279 and 10 537 participants respectively were included in the main NO2and PM analyses at assessments in 1998-2011. Overall, there were no statistically significant associations with any air pollutant or traffic exposure. Sensitivity analyses including in asthmatics only, females only or using back-extrapolated NO2and PM10for assessments in 1985-2002 (ECRHS, NSHD, SALIA, SAPALDIA) did not alter conclusions. In never-smokers, all associations were positive, but reached statistical significance only for chronic phlegm with PMcoarseOR 1.31 (1.05 to 1.64) per 5 μg/m3increase and PM10with similar effect size. Sensitivity analyses of older cohorts showed increased risk of chronic cough with PM2.5abs(black carbon) exposures. Conclusions: Results do not show consistent associations between chronic bronchitis symptoms and current traffic-related air pollution in adult European populations.