Effect of Waterpipe Size on Smoking Behavior and Exposures

Understanding the Effect of Waterpipe Size on Smoking Behavior, Toxicant Exposures and Subjective Experiences

The goal of this clinical trial is to learn how waterpipe (WP) size affects smoking behavior, toxicant exposure, and subjective experiences in young adult WP smokers (ages 21-39). The main questions it aims to answer are:

• Does WP size change puffing behavior?
• Does WP size change exposure to nicotine and carbon monoxide?
• Does WP size change perceptions of harm, satisfaction, craving, or withdrawal?

Participants will smoke small, medium, and large WPs in separate sessions. Researchers will measure puffing behavior, saliva nicotine, exhaled carbon monoxide, and survey responses before and after each session.

Study Overview

• Status: Completed
• Conditions: Waterpipe Size
• Intervention / Treatment: Other: Waterpipe size

Detailed Description

This study will examine the effect of waterpipe (WP) size manipulation on smoking behavior, toxicant exposure, and subjective experiences among young adult WP smokers. A total of 40 participants ages 21-39 will complete a 2x3 crossover design, where the within-subject factors are time (pre vs. post WP smoking) and study condition (small vs. medium vs. large). Each participant will attend three 45-minute laboratory sessions, each using a different WP size.

Aim 1: To examine the effect of WP size on puffing behavior and toxicant exposure. Puff topography parameters (puff number, duration, average puff volume, total inhaled volume, and inter-puff interval) will be measured during smoking. Exhaled CO and saliva nicotine concentrations will be measured pre- and post-session.

Aim 2: To examine the effect of WP size on harm perception and subjective experiences. Outcomes include harm perception, WP Evaluation Scale, Duke Sensory Questionnaire, Questionnaire of Smoking Urges (brief), and Minnesota Nicotine Withdrawal Scale.

This project will generate novel evidence on how WP size influences smoking behavior, exposure to nicotine and CO, and user perceptions. Findings will inform the FDA on the potential impact of WP size regulation and help guide the development of size-specific standards to protect public health.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Texas
    • Arlington, Texas, United States, 76019
      • University of Texas at Arlington

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years to 39 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• regular waterpipe smokers (smoking at least once a week for the past 6 months)
• generally healthy and
• able to provide written informed consent; and willing to attend the 3 lab sessions

Exclusion Criteria:

• history of chronic diseases such as diabetes, high blood cholesterol, hepatic disease
• respiratory chronic diseases
• cardiovascular diseases including low or high blood pressure (BP)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: waterpipe regular smokers; waterpipe regular smokers will be invited for 3 lab visits where they are allocated (random order) to smoke 3 waterpipe different sizes.	Other: Waterpipe size; Participants will have 3 lab visits where they are allocated (random order) to smoke a small waterpipe in one visit, smoke a medium waterpipe in a second visit and smoke a large waterpipe in a third visit.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Waterpipe Evaluation Scale	An 11-item questionnaire assessing participants' subjective experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). For analysis, item scores were averaged across the 11 items to produce a mean WES score for each WP size, with higher scores indicating a more satisfactory smoking experience. The scale captures aspects such as satisfaction, taste, cravings, and sensory enjoyment in the throat and chest.	Immediately after the exposure (smoking)
Duke Sensory Questionnaire	A 9-item questionnaire assessing participants' sensory experience of smoking waterpipe (WP) tobacco. Each item is scored on a 7-point Likert scale (1 = "not at all" to 7 = "extremely"). Item scores were averaged across the 9 items to produce a mean DSQ score for each WP size, with higher scores indicating a more positive sensory experience (e.g., satisfaction, perceived nicotine strength, and puff intensity).	Immediately after the exposure (smoking)
Harm Perception Questionnaire	This is a 3-item scale assessing participants' perception of the harmfulness of waterpipe (WP) tobacco smoking. Each item is scored on a 7-point Likert scale ranging from 1 = "a lot less harmful" to 7 = "a lot more harmful." Item scores were averaged across the 3 items to produce a mean harm perception score for each WP size, with higher scores indicating greater perceived harm.	Immediately after the exposure (smoking)
Saliva Nicotine	How participants' nicotine concentrations change based on the different smoked waterpipe sizes	Immediately after the exposure (smoking)
Puff Topography: Smoking Time	The total time spent smoking during a single WP session, measured in minutes. Longer times indicate greater duration of smoking across WP sizes.	During the exposure (smoking), up to 45 mins
Puff Topography: Cumulative Puff Time	The total time spent actively inhaling smoke across all puffs in a WP session, measured in minutes using a puff topography device. Higher values indicate more total inhalation time.	During the exposure (smoking), up to 45 mins
Puff Topography: Puff Duration	The average length of each puff in seconds, measured using a puff topography device in the WP hose. Longer puff duration indicates deeper inhalation per puff.	During the exposure (smoking), up to 45 mins
Puff Topography: Average Flow Rate	The average rate of smoke inhaled per second during puffing, measured in liters per minute with a puff topography device. Higher flow rates indicate faster inhalation.	During the exposure (smoking), up to 45 mins
Puff Topography: Number of Puffs	The total number of puffs taken during a WP session, measured using a puff topography device. Higher counts indicate more frequent puffing.	During the exposure (smoking), up to 45 mins
Puff Topography: Total Smoke Volume Inhaled	Total smoke inhaled during a single WP session, measured in liters using a puff topography device in the WP hose. Higher values indicate greater smoke intake across WP sizes.	During the exposure (smoking), up to 45 mins
Puff Topography: Puff Volume Average	Mean volume of each puff during a WP session, measured in liters using a puff topography device in the WP hose. Higher values indicate larger puff sizes across WP sizes.	During the exposure (smoking), up to 45 mins
Puff Topography: Maximum Puff Volume	The largest single puff volume inhaled during a WP session, measured in liters using a puff topography device. Higher values indicate the strongest inhalation effort across puffs.	During the exposure (smoking), up to 45 mins

Collaborators and Investigators

• Sponsor: The University of Texas at Arlington

Study record dates

Study Major Dates

• Study Start (Actual): April 22, 2022
• Primary Completion (Actual): February 28, 2024
• Study Completion (Actual): March 30, 2024

Study Registration Dates

• First Submitted: December 22, 2022
• First Submitted That Met QC Criteria: January 26, 2023
• First Posted (Actual): January 30, 2023

Study Record Updates

• Last Update Posted (Estimated): November 5, 2025
• Last Update Submitted That Met QC Criteria: October 15, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: 2021-0458

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No