Despite accumulating evidence about its adverse health effects, waterpipe tobacco smoking has become very popular among youth. The aim of this study was to compare smoke exposure and the kinetics of exhaled carbon monoxide (eCO) between waterpipe and cigarette smokers under different conditions.
Using a cross-over study design, changes in eCO and urinary cotinine levels were measured in a cohort of 32 healthy university students following sessions of waterpipe smoking indoor and outdoor. An indoor cigarette smoking session with equal amounts of tobacco was conducted for reference purposes. Both active and passive smokers participated in all sessions.
In indoor sessions we found that among active participants eCO levels were ∼7.5-fold higher in waterpipe users compared to cigarette smokers. eCO levels remained significantly elevated even 10 hours after discontinuing waterpipe smoking. Notably, eCO levels in passive waterpipe smokers were in the same range as in active cigarette smokers. Compared to indoor sessions, eCO levels in active waterpipe users were reduced in outdoor environments. Nonetheless, levels were still higher in these subjects compared to those in active cigarette smokers measured in indoor sessions. Urinary cotinine levels were comparable in active waterpipe and cigarette smokers.
Our results suggest that waterpipe smoking is associated with significantly higher toxicant exposure than cigarette smoking even in outdoor environment. Furthermore, even passive, indoor waterpipe smoke exposure may have significant health hazards compared to those of active cigarette smoking.