Secondhand Effects of Hookah (i.e., Waterpipe) Smoke and Aerosol

April 17, 2026 updated by: Mary Rezk-Hanna, PhD, University of California, Los Angeles

Investigating the Secondhand Effects of Hookah Smoking and Vaping

In the United States, secondhand smoke is the third leading preventable cause of death. Flavored hookah (waterpipe) tobacco smoking, a highly social activity common in hookah bars, is a key source of SHS exposure. While smoke-free air laws have decreased exposure to secondhand smoke, the majority of laws do not include hookah smoking. Thus, as a social outlet for youth and young adults, hookah smoke exposure may harm non-smokers, including women of reproductive age or pregnant, hookah bar workers, children, and individuals with heart and lung disease. While more is known on the acute effects of active hookah smoking and the literature is emerging on active e-hookah vaping, little is known about the acute vascular effects of secondhand exposure to hookah smoke and aerosol. The study aims to examine the acute effects of secondhand exposure of hookah smoke and aerosol on endothelial and vascular function. Eligible volunteers will be invited to participate in a total of 3 study visits (2-3 hours each): e-hookah aerosol exposure, charcoal-heated hookah smoke exposure and smoke-free room air. Non-invasive blood pressure and blood flow measurements will be taken before and after the exposure sessions.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
12

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90095-8361
        • University of California, Los Angeles

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

21 years to 49 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • 21-49 years old
  • Never a smoker: do not use any tobacco products or nicotine delivery systems, including cigarettes, cigars (traditional and filtered), cigarillos, hookah, smokeless tobacco (i.e., loose snus, moist snuff, dip, spit, or chewing tobacco), pipe tobacco, snus pouches, dissolvable tobacco or vaping.
  • no evidence of cardiopulmonary disease by history/physical
  • blood pressure (BP) < 140/90 mmHg
  • resting heart rate (HR) < 100 bpm
  • BMI >18 or < 30kg•m2
  • no prescription medication
  • No exposure to environmental tobacco smoke for at least one week prior to the study date.

Exclusion Criteria:

  • exhaled carbon monoxide >6 ppm
  • (+) pregnancy test
  • other conditions deemed unsafe to participate, such as breastfeeding

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Exposure to Combustible Hookah Smoke
Participants will be exposed to combustible hookah smoke. To mitigate the impact of carryover effects, the exposure sessions will be separated by a minimum of 7-days.
Other: Combustible Hookah Smoke
Exposure to combustible hookah smoke for a duration of 60 minutes.
Experimental: Exposure to Electronic Hookah Aerosol
Participants will be exposed to electronic hookah aerosol. To mitigate the impact of carryover effects, the exposure sessions will be separated by a minimum of 7-days.
Other: Electronic Hookah Aerosol
Exposure to electronic hookah aerosol for a duration of 60 minutes.
Experimental: Exposure to Clean Air
Participants will be exposed to Clean Room Air. To mitigate the impact of carryover effects, the exposure sessions will be separated by a minimum of 7-days.
Other: Clean Room Air
Exposure to room air for a duration of 60 minutes.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Flow-Mediated Dilation (FMD)
Time Frame: Pre- and post- the 60-minute exposure sessions
Using ultrasound, FMD of the brachial artery induced by reactive hyperemia, will be used to measure endothelium-dependent vasodilator function. Baseline diameter and velocity will be recorded for 45 seconds and resumed 30 seconds before cuff deflation and continuously for 2 minutes after deflation to obtain true peak vasodilatory response.
Pre- and post- the 60-minute exposure sessions
Arterial stiffness
Time Frame: Pre- and post- the 60-minute exposure sessions
Using applanation tonometry, pulse wave velocity will be used to measure cebtral arterial stiffness.
Pre- and post- the 60-minute exposure sessions

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of California, Los Angeles

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 25, 2021

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 15, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 15, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 3, 2020

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 3, 2020

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 10, 2020

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 22, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 17, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 20-001570

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

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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