Perceived Harms of Waterpipe Tobacco Heating Sources Among Young Adult Waterpipe Tobacco Smokers.

. Waterpipe tobacco smoking is associated with many negative health outcomes due to toxicants produced by heating the tobacco using charcoal or electrical heaters. Little is known about how young adult waterpipe tobacco smokers perceive harms of these heating sources. . To examine young adult waterpipe tobacco smokers' perceived harms of electrical heaters and charcoal to heat waterpipe tobacco. . This online cross-sectional study enrolled 18- to 32-year-olds who smoked waterpipe tobacco within the past 30 days. Participants completed measures assessing, for each heating source, amount and knowledge of toxicants released (e.g., carbon monoxide, cancer-causing chemicals), perceived safety, worry about inhaling toxicants, perceived health risk, desire to quit, and intention to smoke in the next month. Question order for knowledge of and perceived harms was counterbalanced for each heating source. . Analyses were based on responses from 199 participants. Perceived harms for both heating sources were average to low. Despite some question order effects, participants viewed charcoal as more harmful than electrical heaters. Participants knew more about chemicals released from charcoal than electrical heaters. Greater knowledge of chemicals released by both heating sources correlated positively with perceived harms. Perceived harms were associated with a stronger desire to quit, yet unrelated with likelihood of smoking waterpipe during the next month. . Many young adult waterpipe tobacco smokers view charcoal as more harmful than electrical heaters, although knowledge about harms for each heating source is poor. . Interventions are needed to inform the public about harms of waterpipe heating sources in order to curb use.