Abstract
INTRODUCTION: Waterpipe (WP) tobacco smoking remains popular among US young adults, yet specific regulations for WP devices are lacking. This study examines how WP device size (base volume and height) affects smoking behavior, toxicant exposures, and subjective experiences. AIMS AND METHODS: Thirty-eight individuals who smoke WP aged 21-39 participated in a randomized crossover study. Each completed three 45-min ad libitum smoking sessions using small, medium, and large WP sizes. Saliva nicotine and exhaled carbon monoxide (eCO) were measured before and after smoking. Puff topography was recorded during sessions, and subjective smoking experiences were collected afterwards. RESULTS: Significant differences were observed in saliva nicotine between the three WP sizes, with higher concentrations for the small WP relative to larger sizes (p < .05). Exhaled CO was significantly higher after smoking the large WP compared to smaller sizes (p < .05). Puff topography revealed significant differences and followed a dose-response pattern, with larger size associated with longer puff duration, greater smoke volume inhaled, and larger puff volume (p < .05). The large WP was associated with enhanced subjective experiences for satisfaction and concentration compared to the small WP (p < .05). CONCLUSIONS: WP size substantially impacts smoking experiences and exposures. Regulation of WP size should be essential in comprehensive tobacco control policies aimed at curbing WP use among young adults. These findings will aid in the developing of WP size-specific standards to regulate the marketing and sales of WP devices. Such regulations should aim to minimize toxicant exposure by controlling the dimensions and design of WP components, which can significantly influence smoking behavior and toxicant intake. IMPLICATIONS: This study underscores the critical role of waterpipe (WP) size in shaping smoking behavior, experiences, and exposures among young adults.