Table 2.

Schematic construction of tobacco cigarette, e-cigarette, and waterpipe with their corresponding puffing topographies

Tobacco cigarette	Waterpipe	E-cigarette
Tobacco cigarette users display very little deviation in their smoking topography.31 This allowed for a standardized smoking protocol to be implemented in the form of an ISO 3308 standard (2 s puff duration, 35 mL puff volume, and 60 s duration between puffs). An average smoker consumes roughly between 10 and 20 cigarettes per day.	Waterpipe users usually attend only one smoking session per day which lasts for approximately 1 h. Puff volume, duration, and puffing frequency are all higher in waterpipe users in comparison to tobacco cigarette users. There is no ISO standard for waterpipe smoking, but most of the research groups use the ‘Beirut’ protocol (2.6 s puff duration, 530 mL puff volume, and 17 s duration between puffs).32	E-cigarette users show a much more pronounced deviation in puffing parameters, making a standard vaping protocol hard to design.33  ,  34 In 2019, an ISO 20768 standard was developed for routine analytical vaping experiments (3 s puff duration, 55 mL puff volume, and 30 s duration between puffs).