OBJECTIVES: To investigate whether air pollution is a potential risk factor for airways obstruction.METHODS: A prospective cohort study (11.3 +/- 2.9 years) that took place in two areas (Eordea where concentration of PM10 was high and Grevena, Greece). We used the MRC questionnaire, spirometry, and anterior rhinomanometry at both visits.RESULTS: Initially we examined 3046 subjects. After excluding chronic obstructive pulmonary disease (COPD) patients, we re-examined 872 subjects and 168 of them had developed COPD (Grevena: 24.3%, Eordea: 18.5%). Multivariable logistic regression analysis showed that the area of residence and thus exposure to air pollution was not a risk factor for the development of COPD (OR: 0.51, 95% CI: 0.18-1.46, P = 0.21). On the other hand, residence in Eordea was strongly related to the development of severe nasal obstruction (OR: 11.47, 95% CI: 6.15-21.40, P < 0.001). Similar results were found after excluding patients with COPD stage I as well as in the subgroup of never smokers.CONCLUSION: Air pollution was associated with severe nasal obstruction but not with COPD development.