Traditional shisha smoking is practiced by ~10% of the Qatari adult population. Although based on tobacco leaves, shisha smoking exposes the airway epithelium to a chemical insult of intensity and duration different from that of cigarette smoking. This study, a collaboration between WCMC-Qatar and WCMC-New York and the Hamad Medical Corporation (HMC), is focused on defining the biology of the airway epithelium of shisha smokers compared to non-smokers. Using approved protocols, bronchoscopy will be used to sample the airway epithelium, the site of the earliest changes associated with smoking. The transcriptome of the recovered epithelium will be assessed in the genomic core WCMC-Qatar for gene expression using microarrays and complete RNA sequencing using massive parallel sequencing.Based on this information, the epithelial DNA will be assessed for relevant SNPs, copy number variations and methylation status. Parallel studies will be carried out in cigarette smokers, providing a comprehensive catalog of shisha smoking-induced changes compared to cigarette smokers and non-smokers in this population.