Efficacy of Respiratory Protection Against the Effects of Wood Smoke Exposure in Young Healthy Adults (MASKON)
- Conditions
- Healthy
- Interventions
- Other: NIOSH certified N95 personal face covering (mask)Other: Surgical Mask
- Registration Number
- NCT06066749
- Lead Sponsor
- University of North Carolina, Chapel Hill
- 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.
- Detailed Description
Wood smoke pollution is a common problem across the world, including in the US. This wood smoke comes from people using wood to heat and cook, as well as from wildfires. Woodsmoke (WS) derived from wildland fires account for a significant fraction of ambient air pollution, including particulate matter (PM) and volatile organic compounds (VOCs) in the gaseous phase. It remains unclear whether the gaseous fraction of woodsmoke contributes to acute or chronic health effects. The present 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. Results from this study will also increase understanding of how wood smoke exposure adversely affects the functioning of the human cardiovascular and respiratory systems. This understanding may be especially important for patients with cardiopulmonary diseases.
Study design Volunteers will participate in two exposure sessions. Each exposure session will be 2 hours in duration and will take place in a 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. During the exposure, fluctuations in the WS concentration will be corrected by controlling the flow of dilution air. The concentrations of carbon monoxide and nitrogen oxides will be monitored continuously to maintain the safety of the atmosphere.
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. The CAPR is a commercially available, integrated helmet system that delivers filtered air directly to the participant's breathing zone. A flexible lens (shield) with a thin film cuff is attached to the front of the helmet. The thin filament is pulled under the participant's chin to ensure that breathing space is enclosed but not sealed. This allows air to "leak" around the cuffs margin using positive pressure generated by the internal air pump.
In the modified MAXAIR CAPR used during this study's exposure sessions, an external pump and different filtering media will be added to remove volatile organic compounds and/or particulate matter from the woodsmoke being delivered to the breathing space. The flow rate generated will be significantly higher than the participant's maximum peak inspiratory flow to ensure a positive pressure is maintained during the entire two-hour exposure session. Additional safety monitoring enhancements, notably a pressure sensor at the interface of the tubing bundle and pump heads, have been added to ensure that the pump maintains a constant flow and pressure as it delivers filtered woodsmoke to the volunteer's breathing zone.
During one of the exposures, virtually all particulate matter (PM) and volatile organic compounds (VOC's) will be removed using commercially available P100/VOC respirator filters. During the other exposure, only the PM will be removed from the woodsmoke. The participant will be blinded as to what filters are used during each exposure. The flow rate of filtered woodsmoke into the CAPR will be monitored to ensure that it exceeds the respiratory rate and peak inspiration flow of the subject (\>180 lpm). The PM filtering medium used with this respirator will be P100 filters (3M, cat. #: 2097) or equivalent. The PM/VOC filter will consist of 3M cartridge (60925 or equivalent). A follow-up visit will be scheduled approximately 24 hr after each exposure during which bronchoalveolar lavage and NELF procedures will be performed (as described below).
Recruitment & Eligibility
- Status
- RECRUITING
- Sex
- All
- Target Recruitment
- 50
Not provided
Not provided
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- SEQUENTIAL
- Arm && Interventions
Group Intervention Description NIOSH certified N95 personal face covering (mask) NIOSH certified N95 personal face covering (mask) During the third woodsmoke exposure, half of the subjects will be randomly assigned to wear a NIOSH (National Institute of Occupational Safety \& Health) certified N95 personal face covering (mask) while undergoing an exposure to approximately 500 μg/m\^3 wood smoke for 2 hours while exercising intermittently (15 min exercise followed by 15 min rest) on a stationary bike at a workload sufficient to maintain approximately 12 L/min/m\^2 minute ventilation. Surgical Mask Surgical Mask During the third woodsmoke exposure, half of the subjects will be randomly assigned to wear a surgical mask while undergoing an exposure to approximately 500 μg/m\^3 wood smoke for 2 hours while exercising intermittently (15 min exercise followed by 15 min rest) on a stationary bike at a workload sufficient to maintain approximately 12 L/min/m\^2 minute ventilation.
- Primary Outcome Measures
Name Time Method Change in polymorphonuclear neutrophils (PMN%) in the Bronchoalveolar lavage fluid (BAL) Approximately 24 hours post exposure. Airway inflammation will be assessed by the % PMN in the (BAL)
- Secondary Outcome Measures
Name Time Method Change in Forced Vital Capacity (FVC) (liter) Immediately after each exposure and approximately 24 hours post exposure. FVC is determined by spirometry
Percent Change in Heart Rate Variability Immediately after each exposure and approximately 24 hours post exposure. Heart rate variability will be collected by the Holter monitor recording.
Change in concentration of Blood Fatty Acids (ng/mL) Immediately after each exposure and approximately 24 hours post exposure. Blood sample will be collected for fatty acids analysis.
Change in concentration of Cytokines in Nasal Epithelial Lining Fluid (NELF) (ng/mL) Immediately after each exposure and approximately 24 hours post exposure. NELF samples will be collected for cytokine measurements.
Change in concentration of interleukin-6, interleukin-8, interleukin-1 beta, and tumor-necrosis factor alpha in blood. (pg/mL) Immediately after each exposure and approximately 24 hours post exposure. Blood will be collected prior to and post exposure to analyze for inflammatory markers.
Change in Forced Expired Volume in the First Second (FEV1) (liter) Immediately after each exposure and approximately 24 hours post exposure. FEV1 is determined by spirometry
Change in concentration of C-reactive protein in blood. Immediately after each exposure and approximately 24 hours post exposure. Blood will be collected prior to and post exposure to analyze for inflammatory markers.
Change in Diameters (mm) of Retinal Arteries and Veins Immediately after each exposure and approximately 24 hours post exposure. Retinal images will be taken using an FDA-approved, commercially available, non-mydriatic fundus camera. Images will be taken from both eyes.
Change in concentration of Blood Cholesterol (ng/mL) Immediately after each exposure and approximately 24 hours post exposure. Blood sample will be collected for blood cholesterol analysis.
Trial Locations
- Locations (1)
U.S. Environmental Protection Agency Human Studies Facility
🇺🇸Chapel Hill, North Carolina, United States