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

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to understand how wood smoke affects heart and lung health in healthy adults when exposed to different components of the smoke. Participants will wear a special respirator that filters out various elements of the smoke during two separate sessions. The trial is suitable for healthy individuals aged 18-35 who can comfortably exercise on a bike for about an hour. As an unphased trial, it offers participants the opportunity to contribute to important research on environmental health impacts.

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 prior data suggests that this protocol is safe for healthy adults?

Research has shown that N95 masks are generally safe and effective for protecting people from harmful substances in smoke, such as during wildfires. N95 masks filter out most harmful particles and are designed for safety in various settings, not just workplaces.

In contrast, surgical masks offer less protection against smoke. They mainly filter larger particles and are less effective for the tiny particles or gases found in smoke.

Both types of masks have been widely used and are considered safe for general use, with no major safety concerns about wearing them during this study. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores how different masks—specifically, NIOSH certified N95 respiratory masks and surgical masks—can protect healthy adults from wood smoke exposure. While typical treatments for smoke exposure focus on managing symptoms after exposure, this study looks at prevention through personal protective equipment. The unique aspect here is evaluating the effectiveness of these masks in a controlled environment where participants are exposed to a specific concentration of wood smoke while exercising. This could provide valuable insights into the best ways to protect individuals who are regularly exposed to wood smoke, enhancing safety measures beyond traditional symptom management.

What evidence suggests that this trial's treatments could be effective for respiratory protection against wood smoke?

In this trial, participants will wear different types of masks while exposed to wood smoke. Research has shown that N95 masks, one of the masks tested, can block at least 95% of tiny particles, including those as small as 0.3 micrometers. This makes them effective at filtering most small particles in wood smoke. Some studies suggest these masks also help reduce exposure to certain gases in wood smoke.

Surgical masks, another type tested in this trial, are moderately effective, blocking 25–81% of larger particles. They do not filter very small particles and gases as well as N95 masks. Both types offer some protection, but N95 masks generally perform better at keeping harmful particles and gases out. ^{6 7 8 9 10}

Who Is on the Research Team?

James Samet, PhD

Principal Investigator

Environmental Protection Agency (EPA)

Are You a Good Fit for This Trial?

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 for a Trial Participant

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

What Are the Treatments Tested in This Trial?

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.

How Is the Trial Designed?

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+

Published Research Related to This Trial

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]

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]

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]

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]

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]

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]

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]

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]

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]

Citations

1. ncceh.ca ncceh.ca/resources/evidence-reviews/rapid-review-evaluating-effectiveness-masks-and-respirators-against

Rapid review: Evaluating the effectiveness of masks and ... One quasi-experimental study reported that surgical masks and N95 respirators may be effective at reducing concentrations of pine needle ...

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10926833/

N95 Respirators for Cardiovascular Protection During ... N95 respirators can reduce PM 2.5 exposure when properly fit and worn; however, their effectiveness in real‐world settings remains unknown.

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Effectiveness of wearing face masks against traffic particles on ... The N95 respirator has an established filtration ability of at least 95% against particles down to 0.3 μm according to NIOSH testing protocols.

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Non-Fit Tested Respirators for Wildfire Smoke Protection in ... Two modelling studies were identified which attempted to estimate respirator protection from air pollution (a range of particulate diameters) ...

5. sciencedirect.com sciencedirect.com/science/article/pii/S0379711223000796

The effectiveness of filter material for respiratory protection ... N95, P95, and P100 filters were also effective at filtering some gaseous species, especially those with nuisance VOC capabilities compared to the bandana.

6. blogs.cdc.gov blogs.cdc.gov/niosh-science-blog/2025/01/13/protecting-from-wildfire-smoke/

How to Protect Workers and the Public from Wildfire Smoke A NIOSH Approved® respirator (eg, N95® or P100®) can provide workers protection from breathing in harmful substances, including wildfire smoke, ash, and very ...

7. lni.wa.gov lni.wa.gov/safety-health/safety-topics/topics/wildfire-smoke

Wildfire Smoke An N95 respirator will have information printed on it to indicate it is NIOSH approved. See How to tell if your N95 Respirator is NIOSH Approved.

8. ncbi.nlm.nih.gov ncbi.nlm.nih.gov/books/NBK580378/

Respiratory Protection for the Public - NCBI - NIH This chapter examines experiences with the use of respirators, medical masks, and face coverings outside of occupational settings to mitigate inhalation ...

9. fda.gov fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-surgical-masks-face-masks-and-barrier-face-coverings

N95 Respirators, Surgical Masks, Face Masks, and Barrier ... These surgical N95 respirators are class II devices regulated by the FDA, under 21 CFR 878.4040, and CDC NIOSH under 42 CFR Part 84. N95s ...

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Respiratory Protection Requirements During Fire Cleanup ... Employers may provide a disposable filtering facepiece respirator (N95) to employees in areas where vegetation or untreated wood alone has burned, in lieu of ...