Respiratory Protection for Healthy Adults Exposed to Wood Smoke

(MASKON Trial)

Overseen By Patrice Ratliffe

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of North Carolina, Chapel Hill

Must not be taking: Steroids, Anticoagulants, Beta-blockers, others

Disqualifiers: Cardiovascular disease, Respiratory disease, Diabetes, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 4

50 Participants Needed

Trial Summary

Do I need to stop taking my current medications for the trial?

Yes, you will need to stop taking certain medications for the trial. You cannot take any prescription or over-the-counter medications (except birth control) for one week before the bronchoscopy. Additionally, you must stop taking dietary supplements, vitamins, Omega-3 supplements, prebiotics, probiotics, and antihistamines for the duration of the study.

What data supports the effectiveness of the treatment NIOSH certified N95 personal face covering (mask) and Surgical Mask for healthy adults exposed to wood smoke?

Research shows that N95 masks can significantly reduce exposure to harmful particles in the air, like those found in wood smoke, by more than 14 times. Surgical masks also help, but to a lesser extent, reducing exposure by about 1.7 times. This means wearing these masks can lower the risk of respiratory issues when exposed to wood smoke. ^{1 2 3 4 5}

Are N95 and surgical masks safe for humans?

N95 and surgical masks are generally safe for humans to use. They have been shown to reduce exposure to harmful particles in the air, such as those from pollution and smoke, although N95 masks may feel less comfortable and harder to breathe through compared to surgical masks. ^{5 6 7 8 9}

How does using N95 and surgical masks as a treatment for wood smoke exposure differ from other treatments?

Using N95 and surgical masks for wood smoke exposure is unique because it involves wearing protective face coverings to filter out harmful particles from the air, unlike other treatments that might focus on medication or other interventions. N95 masks, in particular, offer significant protection by reducing exposure to particulate matter by more than 14 times, which is more effective than surgical masks and other types of face coverings. ^{2 5 10 11 12}

What is the purpose of this trial?

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.

Research Team

James Samet, PhD

Principal Investigator

Environmental Protection Agency (EPA)

Eligibility Criteria

The MASKON trial is for young, healthy adults aged 18-35 with normal lung and heart function. Participants must have a BMI between 19 and 30, be able to do mild exercise on a bike, and be fully vaccinated against COVID-19.

Inclusion Criteria

I am between 18 and 35 years old, healthy, with a BMI between 19 and 30.

You have a normal electrocardiogram.

My lung function is within the normal range for my age, gender, ethnicity, and height.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Exposure Session 1

Participants undergo the first exposure to woodsmoke with virtually all particulate matter and volatile organic compounds removed, while exercising intermittently.

2 hours

1 visit (in-person)

Follow-up Session 1

Participants are monitored for health effects approximately 24 hours after the first exposure, including bronchoscopy and nasal epithelial lining fluid collection.

1 day

1 visit (in-person)

Exposure Session 2

Participants undergo the second exposure to woodsmoke with only particulate matter removed, allowing volatile organic compounds to pass, while exercising intermittently.

2 hours

1 visit (in-person)

Follow-up Session 2

Participants are monitored for health effects approximately 24 hours after the second exposure, including bronchoscopy and nasal epithelial lining fluid collection.

1 day

1 visit (in-person)

Final Follow-up

Participants are monitored for safety and effectiveness after the completion of both exposure sessions.

4 weeks

Treatment Details

Interventions

• NIOSH certified N95 personal face covering (mask)
• Surgical Mask

Trial Overview This study tests the effectiveness of different masks (N95 respirator vs surgical mask) in protecting against wood smoke exposure during intermittent exercise over three sessions. It measures cardiovascular health before and after exposure.

Participant Groups

Group I: Wood Smoke 1 Experimental Treatment 2 Interventions

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.

Who Is Running the Clinical Trial?

University of North Carolina, Chapel Hill

Lead Sponsor

Trials

1,588

Recruited

4,364,000+

Environmental Protection Agency (EPA)

Collaborator

Trials

40

Recruited

95,500+

Findings from Research

Using a soft mannequin head improved the fit of masks, resulting in significantly higher protection for healthcare workers (HCWs) when the infected patient wore a mask, with simulated workplace protection factors (sWPF) reaching up to 17,038.

The study found that while N95 respirators on the HCW provided limited protection (sWPF up to 7.53), any mask worn by the infected source greatly reduced aerosol exposure, highlighting the importance of respiratory source control in preventing the spread of infections.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Respiratory source control versus receiver protection: impact of facemask fit. Mansour, MM., Smaldone, GC.[2013]

Forest firefighters exposed to wood and vegetative smoke during prescribed burns had an average PM(2.5) concentration of 280 μg/m(3), significantly higher than the 16 μg/m(3) measured on non-burn days, indicating potential health risks during burn activities.

Self-assessments of smoke exposure by firefighters correlated well with actual PM(2.5) measurements, suggesting that their qualitative evaluations can effectively estimate personal exposure levels, although some extreme situations may exceed recommended safety thresholds.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Personal PM(2.5) exposure among wildland firefighters working at prescribed forest burns in Southeastern United States. Adetona, O., Dunn, K., Hall, DB., et al.[2013]

Filtration type face masks are effective in preventing the spread of smoke particles expelled during coughing, as demonstrated by photographs of the particles' dispersion.

The study highlights the importance of using filtration masks to reduce the transmission of potentially harmful particles in the air, showcasing their protective role in public health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The efficacy of face masks. Shah, M., Crompton, P., Vickers, MD.[2018]

In a study involving 80 wildland firefighters during the 2021 fire season, the use of N95 masks was associated with a significant reduction in symptoms like cough and throat irritation by the end of their work rotations.

Despite the benefits of wearing N95 masks, many firefighters faced challenges such as discomfort and high work difficulty, which limited their consistent use, highlighting the need for improved strategies to encourage respiratory protection.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Respiratory Tract and Eye Symptoms in Wildland Firefighters in Two Canadian Provinces: Impact of Discretionary Use of an N95 Mask during Successive Rotations. Cherry, N., Broznitsky, N., Fedun, M., et al.[2023]

N95 respirators provide the highest level of protection against particulate air pollution, reducing exposure by over 14 times, while synthetic-fiber masks offer moderate protection that varies with aerosol size.

In a case study of the 2012 Washington state fire season, N95 respirators could significantly reduce respiratory hospitalizations due to smoke by 22%-39%, while natural-fiber masks showed only minor benefits (2%-11%) due to their lower filtration efficiency.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Quantifying the Health Benefits of Face Masks and Respirators to Mitigate Exposure to Severe Air Pollution. Kodros, JK., O'Dell, K., Samet, JM., et al.[2021]

The study tested the effectiveness of four types of respiratory protection (RP) against volcanic ash, finding that the N95-equivalent mask had the lowest Total Inward Leakage (TIL) at 9%, indicating it provides the best protection among the tested options.

Standard surgical masks and basic flat-fold masks performed poorly, with TIL rates of 35% and 24% (with an added bandage), highlighting the importance of using more effective masks like the N95-equivalent during volcanic ashfall situations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effectiveness of respiratory protection worn by communities to protect from volcanic ash inhalation. Part II: Total inward leakage tests. Steinle, S., Sleeuwenhoek, A., Mueller, W., et al.[2019]

From 1984 to 1995, there were 41 incidents resulting in 45 deaths due to asphyxiation or chemical poisoning while using respirators, highlighting significant safety concerns in respiratory protection practices.

Most fatalities were linked to regulatory violations and improper training, suggesting that adherence to safety regulations and proper training could have prevented these tragic outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fatal injuries in the United States involving respirators, 1984-1995. Suruda, A., Milliken, W., Stephenson, D., et al.[2022]

Respirator cartridges can effectively reduce firefighter exposure to certain respiratory irritants during overhaul activities, particularly for formaldehyde and acetaldehyde, but may not meet the stricter NIOSH exposure limits for formaldehyde, indicating potential safety concerns.

The study developed a method to evaluate respirator effectiveness against 91 contaminants found in smoke, highlighting the need for future research to include specific irritant gases and additional contaminants to ensure comprehensive protection for firefighters.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Method development study for APR cartridge evaluation in fire overhaul exposures. Anthony, TR., Joggerst, P., James, L., et al.[2007]

Wildland firefighters were found to be exposed to potentially harmful levels of carbon monoxide, particulates, and silica during fire seasons from 1986 to 1989, with some measurements nearing or exceeding recommended occupational exposure limits.

Formaldehyde levels occasionally exceeded 0.37 mg/m3, suggesting a risk of eye or respiratory irritation, indicating that current 8-hour exposure limits may need to be adjusted to better protect firefighters under their specific working conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Occupational exposures in California wildland fire fighting. Materna, BL., Jones, JR., Sutton, PM., et al.[2013]

A rapid review of 48 laboratory studies identified five promising decontamination methods for N95 masks: hydrogen peroxide vapor, ultraviolet irradiation, dry heat, wet heat/pasteurization, and microwave ovens.

While these methods show potential for safely reusing N95 masks, the evidence is limited, and more research is needed in real-world settings to confirm their effectiveness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Mask decontamination methods (model N95) for respiratory protection: a rapid review. Probst, LF., Guerrero, ATG., Cardoso, AIQ., et al.[2021]

Wearing a gas mask significantly increases the work of breathing and other respiratory effort indexes in healthy individuals, both at rest and during exertion, indicating that while the mask provides protection, it also makes breathing more laborious.

Despite the increased respiratory effort, the gas mask does not significantly affect breathing patterns or worsen hypoxemia during physical activity, suggesting that it can be used safely without major impacts on oxygen levels.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Impact of Gas Masks on Work of Breathing, Breathing Patterns, and Gas Exchange in Healthy Subjects. Bourassa, S., Bouchard, PA., Lellouche, F.[2019]

Covering an N95 mask with a surgical mask, cloth mask, or face shield significantly affects the metabolic demands and internal breathing environments, indicating that these combinations can alter how well the N95 functions.

The study utilized a systematic approach with three N95 models and six covering conditions, measuring various respiratory parameters under different work rates, which highlights the importance of understanding how mask combinations impact breathing efficiency.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Evaluation of Surgical N95 Respirators Covered With Combinations of Masks and Face Shield. Powell, JB., Quinn, T., Walbert, G., et al.[2023]

References

1. United States pubmed.ncbi.nlm.nih.gov

Respiratory source control versus receiver protection: impact of facemask fit. [2013]

2. England pubmed.ncbi.nlm.nih.gov

Personal PM(2.5) exposure among wildland firefighters working at prescribed forest burns in Southeastern United States. [2013]

3. England pubmed.ncbi.nlm.nih.gov

The efficacy of face masks. [2018]

4. Switzerland pubmed.ncbi.nlm.nih.gov

Respiratory Tract and Eye Symptoms in Wildland Firefighters in Two Canadian Provinces: Impact of Discretionary Use of an N95 Mask during Successive Rotations. [2023]

5. United States pubmed.ncbi.nlm.nih.gov

Quantifying the Health Benefits of Face Masks and Respirators to Mitigate Exposure to Severe Air Pollution. [2021]

6. Germany pubmed.ncbi.nlm.nih.gov

The effectiveness of respiratory protection worn by communities to protect from volcanic ash inhalation. Part II: Total inward leakage tests. [2019]

7. England pubmed.ncbi.nlm.nih.gov

Fatal injuries in the United States involving respirators, 1984-1995. [2022]

8. England pubmed.ncbi.nlm.nih.gov

Method development study for APR cartridge evaluation in fire overhaul exposures. [2007]

9. United States pubmed.ncbi.nlm.nih.gov

Occupational exposures in California wildland fire fighting. [2013]

10. England pubmed.ncbi.nlm.nih.gov

Mask decontamination methods (model N95) for respiratory protection: a rapid review. [2021]

11. United States pubmed.ncbi.nlm.nih.gov

Impact of Gas Masks on Work of Breathing, Breathing Patterns, and Gas Exchange in Healthy Subjects. [2019]

12. United States pubmed.ncbi.nlm.nih.gov

Evaluation of Surgical N95 Respirators Covered With Combinations of Masks and Face Shield. [2023]