After agreement with the written informed consent, 36 volunteers, male and female, aged between 18 and 70 years will be recruited at Medical School University of Sao Paulo and in the Ambulatory of Smoking Cessation Program of the Clinics Hospital. Exclusion criteria are inability to taste saccharin, nasal surgery, respiratory infection in the previous 30 days to the enrollement into the study. All volunteers will be assessed at Basal, 6 months and 12 months. The present study aims to assess the effects of smoking cessation on the airway defense mechanism, airway inflammation and genomics (miRNAs) in humans by using (a) saccharin transit time test to assess mucociliary clearance; (b) mucus physical properties; (c) EBC pH; (d) Nasal lavage pH, cellularity,cytokines (IL-1β, TGF-β, TNF-α, IL-4, IL-6, IL-8, IL-10, IL-13, MPO, MUC5AC, cotinine, proteomics, (e) lung function; (f) genomics (miRNAs) and (g) quality of life with rhinosinusitis questionnaire (SNOT20), sleep disturbances questionnaire.