I. To conduct a pilot cross-sectional study of electronic (e)-cigarette (cig) users, never-smokers, and smokers (n=30), assessing use patterns and biomarkers by bronchoscopies using bronchoalveolar lavage (cell counts, inflammatory cytokines, and untargeted metabolomics), and bronchial brushings for gene expression (micro ribonucleic acid [miRNA] and messenger ribonucleic acid [mRNA]).