Efficacy of Respiratory Protection Against the Effects of Wood Smoke Exposure in Young Healthy Adults (MASKON) — MASKON  

Healthy Clinical Trial

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

Status Enrolling by invitation

Clinical Trial Summary

Purpose: The study is designed to investigate cardiovascular effects of young healthy human subjects exposed to wood smoke.

Participants: Approximately 30 young (18-35 years old) healthy subjects to complete.

Procedure (methods): After consenting to participate in the study, participants will undergo 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. There are a total of three separate exposure sessions. During the first two exposure sessions, participants will wear, in randomized order, a half-face elastomeric respirator fitted with particulate filters alone (hereafter referred to as "PM mask") or particulate filters and a hydrocarbon sorbent (hereafter referred to as "VOC mask"). During the third exposure session, participants will be randomly assigned to wear either a surgical mask or an N95 respirator. Venous blood samples and measurements of lung, cardiac and vascular function will be made prior to and immediately following each exposure. Induced sputum samples and nasal epithelial lining fluid will be collected approximately 24 hours post each exposure.

Clinical Trial 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. The purpose of this research study is to investigate the cardiovascular effects of exposure to wood smoke in young, healthy human subjects. 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.

Consenting Day:

The consent day visit is expected to last about 4-5 hours. The investigators will review the inclusion and exclusion criteria and the participants' medical conditions and current medications. The investigators will go over the study in detail so the participant is as informed as possible before consenting to being part of this study. The participant will then sign all consent forms and receive one set of signed copies. The participant will also tour the exposure chambers following the consenting process.

After consenting to participate in the study, participant's vital signs and approximately 4 ml of blood will be collected. This blood will be measured for specific analytes to ensure participants can safely complete this study. As part of the consenting day, participants will undergo exercise training to determine the level of exercise needed to perform to reach the target minute ventilation for this study. Participants will pedal on an exercise bike at various levels of resistance for 5-15 minute periods and have minute ventilation (amount of air breathed per minute) measured at regular intervals using displacement bands around the torso to measure minute ventilation from chest expansion while breathing. Participants will be fitted for a half-face elastomeric respirator to ensure they are wearing the proper size during the training session. All participants will be wearing the same half-face respirator used during exposure sessions 1 and 2.

The participant will perform a breathing test (spirometry) to measure lung function. The participant will breathe through a filter into a plastic tube, while being coached by members of the study team. Participants will be asked to take a full breath in, follow by a hard and fast maximal exhalation. The participant will be asked to do this several times. This test measures the volume of air that can be exhaled and the rate of airflow during exhalation after a maximal inhalation. This is a method to measure lung function which must meet certain criteria (lung capacity and volume) prior to exposure in order for the participant to remain in the study. Lung function test results should be equal to or greater than 80% of the reference value to continue participation in the study.

Participants will also undergo procedures for nasal epithelial lining fluid sampling (nasal mucosa) and induced sputum collection. It is known that less than half of normal, healthy people can produce a sputum sample that is of acceptable quality for analysis. The study will end if a participant is a non-producer or the quality of the sputum produced does not meet the study inclusion criteria. In this event, the participant will be reimbursed for the consenting session. Participants who meet all inclusion criteria will be contacted with further instructions.

Exposure days:

The study team will contact and send reminders to all participants a few days before the exposure session. Participants should avoid smoke, fumes, alcohol, and strenuous exercise 24 hours prior to all visits, and abstain from pan fried or grilled meat after midnight of the exposure day. Participants will be asked to eat a light breakfast and arrive at the EPA medical station by 8:00 am. The study team will make ensure that all participants understand the importance of arriving earlier to ensure the investigators have adequate time to process all samples and data. Participants who arrive after 8:00 am will be unenrolled from the study.

Prior to exposure, a study team member will collect the follow from each participant:

1. Vital signs (heart rate, respiratory rate, blood pressure, oxygen saturation level) and an electronic symptom questionnaire.

2. Heart Rate Variability via a Holter monitor. A study team member will attach ten electrocardiogram (ECG) leads to the participants' chest. It may be necessary to clean and shave areas of the chest where these leads will be placed. Participants will be asked to not apply excessive deodorant, skin lotions, and body sprays on as these may interfere with data recording. The leads will be connected to 2 monitors (small recording devices about the size and weight of a cell phone) to obtain heart rate and rhythm readings. It is preferable that the electrodes will stay in place for approximately 4 days as these measurements will be collected several times during the study, however, participants will be given the option to remove the electrodes by the end of each exposure day. To begin recording, participants will be asked to recline quietly for 30 minutes. It is important that the participant does not fall asleep during this 30-minute period. These measurements will allow the investigators to determine whether wood smoke exposure causes small changes in the ability of your nervous system to regulate how your heart beats.

3. Retinal Imaging. An ophthalmic camera will be employed to collect retinal images of all participants before and after each exposure and on the follow-up visit. The participants chin will be rested in front of the camera, while a study team member takes pictures of both eyes. Glasses or contacts must be removed for this test. Participants will be notified to bring contact lens cases and solutions.

4. The study team will continue to store the images for future undesignated studies given the participant's consent. This allows the team to make the best use of the images collected from subjects. Participants will be given a separate consent form for this storage and do not have to allow images to be stored indefinitely in order to participate in this study.

5. Blood Draw. Approximately 60 ml of blood will be drawn (about 4 tablespoons) before and after each exposure and on the follow-up visit. The study team will test this blood to see blood cell function is affected by exposure to wood smoke. A small portion of the blood sample will be used to measure the relative content of various fatty acids present in blood. With permission, the investigators will also store some of the blood obtained during the study for yet-to-be-determined tests.

6. Spirometry will be performed following the same procedure used on the consent day.

7. Ventilation Rate. BioPac bands will be placed around the participants' thorax and abdomen. These bands will be connected to a monitor that wirelessly transmits readings of breathing volume and rate. These measurements will allow the investigators to determine if the participants' exercise workload is sufficient to meet the study's target minute ventilation rate.

Participants will enter the exposure chamber following the pre-exposure protocol listed above. While in the chamber, participants will undergo 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. There are a total of three separate exposure sessions. During the first two exposure sessions, participants will wear, in randomized order, a half-face elastomeric respirator fitted with particulate filters alone (hereafter referred to as "PM mask") or particulate filters and a hydrocarbon sorbent (hereafter referred to as "VOC mask"). During the third exposure session, participants will be randomly assigned to wear either a surgical mask or an N95 respirator. The concentration of wood smoke used in this study (approximately 500 μg/m^3) is below what is reported for those using biomass burning for heating and food preparation, those firefighters are exposed to, and those living in the area of a forest fire or agricultural burning are exposed to. Chamber conditions will be at a comfortable temperature and relative humidity. Participants will perform mild exercise on a stationary bicycle in the chamber every other 15 minutes alternating with resting period for a total of 1 hour of exercise per chamber exposure. The target ventilation rate will be maintained at approximately 12 L/min/m^2 and monitored using pneumotach and BioPac methods. A study coordinator or other trained person will be observing from outside the chamber at all times. During the exposure, heart rate and oxygen saturation will be monitored by placing a device (pulse oximeter) on the participants' finger. If it appears the participant is experiencing significant discomfort, breathing or heart problems, the exposure will be terminated immediately. In addition, the participant may elect to terminate the exposure at any time for any reason. Participants who do not complete the study protocol will be fully compensated that day's session but will be ineligible for further participation in the study.

Immediately following the exposure, participants will:

1. Fill out a symptom score questionnaire electronically.

2. Have your vital signs checked.

3. Have blood drawn (Approximately 60 ml, about 4 tablespoons).

4. Have a breathing test (spirometry).

5. Recline quietly for 30 minutes while heart rhythm is recorded.

6. Have retinal pictures will be taken.

7. Eat a low-fat lunch brought from home. At this time, the study team will encourage participants to take a shower in a private shower facility at the HSF to get rid of the wood smoke odor. Towel, soap, and shampoo will be provided. The participant's belongings will be securely stored during all visits.

Participants will be assessed and discharged by the study team following the completion of each exposure day.

Follow up visit (about 4 hours):

Participants will return to the HSF the next morning (approximately 24 hours after exposure) and will:

1. Have vital signs checked.

2. Recline quietly for 30 minutes while your heart rhythm is recorded. Electrodes will be removed from the participants' chest at the end of this test.

3. Have blood pressure and heart rate measured.

4. Fill out a symptom score questionnaire electronically.

5. Complete TracMyAir Questionnaire (see below)

6. Have NELF samples collected.

7. Have samples of induced sputum collected.

8. Have a breathing test (spirometry).

9. Have blood drawn (approximately 60 ml) for analysis.

10. Have retinal pictures taken.

TracMyAir is an application that uses data from nearby monitoring stations to report on local air pollution levels. The study team will use TracMyAir to determine each study participant's daily (24 hour average) ambient PM2.5 and ozone exposure and inhaled dose. TracMyAir calculates daily 24 hour average exposure and dose for the previous 4 days, which allows for a lag analysis. TracMyAir uses EPA's previously developed and evaluated Exposure Model for Individuals (EMI). The EPA staff will enter input data (shown below) into the TracMyAir software for each study participant.

If there are any samples left over after all study information is collected, the study team will continue to store the samples for future undesignated studies given the participant's consent. This allows the team to make the best use of the samples collected from subjects. Participants will be given a separate consent form for this storage and do not have to allow samples to be stored indefinitely in order to participate in this study. ;

Related Conditions & MeSH terms

• Healthy

• NCT number: NCT06066749
• Study type: Interventional
• Source: University of North Carolina, Chapel Hill
• Status: Enrolling by invitation
• Phase: N/A
• Start date: June 2024
• Completion date: December 2027