The aim of this study is to compare exposure to tobacco smoke toxins in individuals who smoke
both cigarettes and Hookah pipes. Sixteen subjects will be hospitalized on the research ward
for two visits of 4 days each. At one visit they will smoke their usual cigarettes in
approximately normal frequency, and at the other visit they will smoke Hookah at least twice
per day. The order of the visits will be randomized. On the fourth day of each visit (when
nicotine, carbon monoxide (CO), and some carcinogen levels will be in a steady state
condition), circadian blood and urine and expired air samples will be collected.