Efficacy of Respiratory Protection Against the Effects of Wood Smoke Exposure in Young Healthy Adults

NCT06066749 | Suspended

• 1 other identifier: 23-1135
• Study Type: interventional
• Target: 50
• Locations: 1 country
• Sites: 1

Brief Summary

Purpose: This study is designed to test whether the gaseous fraction of woodsmoke, volatile organic compounds, produce acute cardiac, respiratory, and systemic inflammatory health effects after controlled exposure to woodsmoke in health, young volunteers. Participants: Approximately fifty, 18-35 year-old healthy volunteers to complete the study. Procedure: After consenting to participate in the study, participants will undergo two exposures to approximately 500 μg/m3 woodsmoke. The two exposures will be held at least 3 weeks apart. Each exposure session will have a follow-up session approximately 24 hr later. During each exposure session, participants will wear a modified MAXAir Systems (Irvine, CA, USA) (TC 21C-1050) controlled air pressure respirator (CAPR) that will deliver filtered woodsmoke directly to the participant's breathing zone. During the first exposure, the CAPR will deliver woodsmoke from which virtually all particulate matter (PM) and volatile organic compounds (VOC's) will be removed. During the second exposure, only the PM will be removed from the woodsmoke, allowing the VOC to pass into the subject's breathing zone. During each session, participants will be exposed for 2 hours while exercising intermittently (15 min exercise followed by 15 min rest) on a stationary bike at a workload sufficient to maintain a minute ventilation of approximately 25 L/min/m2. Venous blood samples and measurements of respiratory, cardiac, and vascular function will be performed prior, immediately following and approximately 18 hrs post each exposure. Approximately 24 hours post-exposure, participants will undergo a bronchoscopy procedure to sample bronchoalveolar fluid and cells for evidence of an inflammatory response to the exposures. Nasal epithelial lining fluid will be also collected approximately 24 hours post each exposure.

Conditions

Healthy

Keywords

Wood Smoke; Respirators; Masking

Outcome Measures

Primary Outcomes (1)

• Change in polymorphonuclear neutrophils (PMN%) in the Bronchoalveolar lavage fluid (BAL)

  Airway inflammation will be assessed by the % PMN in the (BAL)

  Approximately 24 hours post exposure.

Secondary Outcomes (9)

• Change in Forced Expired Volume in the First Second (FEV1) (liter)

  Immediately after each exposure and approximately 24 hours post exposure.

• Change in Forced Vital Capacity (FVC) (liter)

  Immediately after each exposure and approximately 24 hours post exposure.

• Change in Diameters (mm) of Retinal Arteries and Veins

  Immediately after each exposure and approximately 24 hours post exposure.

• Percent Change in Heart Rate Variability

  Immediately after each exposure and approximately 24 hours post exposure.

• Change in concentration of Blood Fatty Acids (ng/mL)

  Immediately after each exposure and approximately 24 hours post exposure.

Study Arms (1)

Wood Smoke 1

EXPERIMENTAL

Volunteers will be be exposed to woodsmoke for 2 hours while exercising in specialized exposure chamber. Woodsmoke (WS) will be generated by smoldering untreated oak and diluting the resulting WS emissions with clean air to achieve a target concentration of WS in the exposure chamber at an average of approximately 500 μg/m3 for the 2-hour exposure period. During the exposure, participants will exercise intermittently using a stationary bicycle with rest periods (i.e., 4 x 15 minutes on, 4 x 15 minutes off). The workload on the bicycle will be pre-determined on the training day to produce a minute ventilation rate of approximately 25 L/min/m2, which is considered a moderate level of exercise.

Other: Filtration of all PM and VOC's; Other: Filtration of VOC's

Interventions

Filtration of all PM and VOC's OTHER

During each exposure session, participants will wear a modified MaxAIR controlled air pressure respirator (CAPR) manufactured by Syntech International (BMD), Irvine, CA, USA, that will deliver filtered woodsmoke directly to the participant. The MaxAIR CAPR is a NIOSH approved (TC 21C-1050) powered air purifying respirator used for infectious disease control in laboratory and medical settings. In the modified MAXAIR CAPR used during this study's exposure sessions, an external pump and different filtering media. For this intervention, virtually all particulate matter (PM) and volatile organic compounds (VOC's) will be removed using commercially available P100/VOC respirator filters (3M cartridge; 60925 or equivalent).

Wood Smoke 1

Filtration of VOC's OTHER

During each exposure session, participants will wear a modified MaxAIR controlled air pressure respirator (CAPR) manufactured by Syntech International (BMD), Irvine, CA, USA, that will deliver filtered woodsmoke directly to the participant. The MaxAIR CAPR is a NIOSH approved (TC 21C-1050) powered air purifying respirator used for infectious disease control in laboratory and medical settings. In the modified MAXAIR CAPR used during this study's exposure sessions, an external pump and different filtering media. For this intervention, virtually all particulate matter (PM)will be removed using commercially available P100 respirator filters (DM; cat. # 2097).

Wood Smoke 1

Eligibility Criteria

• Age: 18 Years - 35 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age 18-35 years old, healthy individuals (Body Mass Index (BMI, kg/m2) values ≥ 19 and ≤ 34, inclusive).
• Weight equal to or greater than 110 lbs. (Requirement to complete bronchoscopy procedure)
• Physical conditioning that allows intermittent, moderate exercise for approximately 60 min during a 2-hour exposure session. The volunteer must be able to complete the exposure exercise regimen at a workload sufficient to induce a minute ventilation rate of approximately 25 L/min/m2 for 15 min without exceeding 80% of projected maximal heart rate.
• Normal ECG.
• Normal lung function based on NHANES III reference values: Forced vital capacity (FVC) ≥ 80% of that predicted for age, gender, ethnicity, and height; Forced expiratory volume in one second (FEV1) ≥ 80% of that predicted for age, gender, ethnicity, and height; FEV1/FVC ratio ≥ 70% (absolute value).
• Oxygen saturation greater than 94% at the time of physical exam.

You may not qualify if:

• Individuals with the following conditions: a) A history of acute or chronic cardiovascular disease, chronic respiratory disease, cancer, rheumatologic disease, neuromuscular disease, or immunodeficiency state, b) Blood pressure readings ≥ 140 systolic and/or ≥ 90 diastolic, c) Diabetes (previously diagnosed or with hemoglobin A1c level equal to or greater than 6.4%) d) Asthma or a history of asthma, e) Bleeding/clotting disorders.
• Individuals with a cardiovascular disease risk score greater than 10% using the ACC/AHA ASCVD risk calculator. (Based on the 10-year risk of heart disease or stroke using the Atherosclerotic Cardiovascular Disease algorithm published in 2013 American College of Cardiology/American Heart Association Guideline on the Assessment of Cardiovascular risk.)
• Individuals who have had recent (within 6 month) abdominal and/or eye surgery, or with any types of hernia, as well as any other contraindications for raised intra-abdominal pressure.
• Individuals who are currently taking systemic steroids or oral anticoagulants long term.
• Individuals who are allergic to:
• Chemical vapors or gases.
• Tape or electrodes on their skin.
• Or individuals with active allergies or currently experience allergy related symptoms
• Individuals who are pregnant, attempting to become pregnant or breastfeeding.
• Individuals who are currently smoking (including vaping, hookah and e-cigarette) or have smoking history within 1 year of study or have an equal to greater than or a 5-pack year smoking history.
• Individuals living with a smoker who smokes inside the house.
• Individuals who are regularly exposed to high levels of vapors, dust, gases, or fumes.
• Individuals who do not read, speak, or understand English well enough to give informed consent.
• Individuals that are unable to perform the exercise required for the study.
• Individuals who are unwilling or unable to stop taking any current dietary supplements or vitamins for the duration of the study.

Sponsors & Collaborators

• University of North Carolina, Chapel Hill: lead
• Environmental Protection Agency (EPA): collaborator

Study Sites (1)

U.S. Environmental Protection Agency Human Studies Facility

Chapel Hill, North Carolina, 27514, United States

Location

Study Officials

• James Samet

  Environmental Protection Agency (EPA)

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: OTHER
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 18, 2023
• First Posted: October 4, 2023
• Study Start: June 1, 2024
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: June 12, 2025

Record last verified: 2025-06

Locations

US (1)