Smokers vs. nonsmokers: understanding their differences.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D005006:Ethnicity; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D012494:Sampling Studies; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology*; D012959:Socioeconomic Factors; D014481:United States