AsthmaLoFNCT07536178
Lungs on Fire: Wildfire Smoke, Incident Diseases, Susceptible Populations, and Community Values in Canada
A study testing Woodsmoke (Lodgepole Pine) exposure and Filtered air exposure in people with Asthma and Chronic Obstructive Pulmonary Disease (COPD), run by University of British Columbia at 1 site in Canada.
Trial summary
Wildfire smoke (WFS) is the leading climate-related risk in Canada and the main source of harmful air pollution. While short-term breathing problems caused by smoke are well known, there is limited knowledge on how repeated exposure contributes to long-term lung disease. Read more about this study
- Who is it for?
- Ages 19 to 80 yearsHealthy volunteers can take part
- Conditions the study is for
- Asthma, Chronic Obstructive Pulmonary Disease (COPD), Lung Cancer
- What is being tested?
- Woodsmoke (Lodgepole Pine) exposure and Filtered air exposure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 24 participants
- Where
- 1 siteCanada
- Study dates
- 26 May 2026to 31 Aug 2030
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 19 to 80 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Healthy Adults between the ages of 19 to 80 (12 of each biological sex assigned at birth).
Who cannot join
- Current smoker (within six months before screening; potential to confound exposure effects).
- History or current diagnosis of any respiratory conditions (including, but not limited to asthma or chronic obstructive pulmonary disease (COPD), asthma/COPD overlap) or other medical conditions that the study physician determines may impact participant safety.
- Any comorbidities or other concerns identified by the study physician which may impact study participation.
- For participants of child-bearing potential: Current pregnancy, or plans to become pregnant during study enrolment.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
Air Pollution Exposure Lab
Vancouver, British Columbia, V5Z1M9
About this study
Wildfire smoke (WFS) is the leading climate-related risk in Canada and the main source of harmful air pollution. While short-term breathing problems caused by smoke are well known, there is limited knowledge on how repeated exposure contributes to long-term lung disease. This study is a controlled human exposure to varying concentrations of WFS in a safe setting. By comparing the effects of different concentrations, this research will improve understanding of health impacts, identify who may be most vulnerable to exposures, and explore biological changes that could lead to chronic illness.
Read the detailed description
PURPOSE: To use responses to controlled human exposures to woodsmoke, as a model of wildfire smoke (WFS), to quantify risk of, and add biological plausibility to, the supposition that WFS-related particulate matter with a diameter of 2.5 micrometers or less (PM2.5) contributes to the development of neurological and chronic lung diseases.
Study Exposure Arms:
Arm A: 3 consecutive days with 2h woodsmoke exposures at 35 µg/m3 of PM2.5 Arm B: 3 consecutive days with 2h woodsmoke exposures at 105 µg/m3 of PM2.5 Arm C: 2 consecutive days of Filtered Air (FA), followed by 1 day with a 2h woodsmoke exposure at 315 µg/m3 of PM2.5
HYPOTHESIS, JUSTIFICATIONS, AND OBJECTIVES Aim 1A: Enhance plausibility for, and quantify risk of, WFS contributions to chronic lung disease.
Hypothesis 1A: The investigators will determine mechanisms that plausibly link WFS exposure to the development of chronic disease, by connecting WFS exposures to lung function decline, asthma, chronic obstructive pulmonary disease (COPD), or lung cancer.
To assess the plausibility of linking WFS exposure to Chronic Lung Diseases such as asthma, COPD, and lung cancer.
To evaluate the biological impacts of WFS on the airways.
- Specifically, what are the effects of exposure concentration, intensity, and time on inflammatory and immunomodulatory responses to WFS exposure?
- Several biological pathways may link WFS exposures with the development of chronic respiratory diseases such as asthma, COPD, and lung cancer. These include effects of oxidative stress and inflammation on epithelial barrier integrity, which may facilitate contact with immune cells, allergen sensitization, increased infection susceptibility, and tissue remodelling that impairs lung function. Epigenetics, notably DNA methylation (DNAm), is another potential mechanism linking WFS to chronic disease, and the airway microbiome may also contribute through several pathways. However, WFS differs from general urban and traffic-related air pollution (TRAP), so effects of TRAP exposure demonstrated to date cannot be assumed to apply to WFS.
Aim 1B: Use a controlled human exposure study to identify, across different intensities of WFS exposure:
1.1 Neurocognitive changes relevant to the development of chronic neurological diseases 1.2 Temporal patterns of onset and resolution in relevant circulating neuro-inflammatory markers 1.3 Sex, age, and genetics as effect-modifying susceptibility factors for the above phenomena
Hypothesis 1B: The investigators will demonstrate disturbances in the brain default mode network (DMN), and intensity-dependent increases in circulating neuro-inflammatory markers, particularly in older individuals and those with genotypes conferring deficient anti-oxidant metabolism or those conferring risk of dementia.
RESEARCH DESIGN A randomized, double-blinded, crossover-controlled human exposure study.
STATISTICAL ANALYSIS Data will be analysed in R using generalized and linear mixed-effects models. Models will run with exposure as a fixed effect and participant ID as a random effect.
- Being tested
- Woodsmoke (Lodgepole Pine) exposure, Filtered air exposure
- Keywords
- Wildfire Smoke, Chronic Lung Disease, Air Pollution, Controlled Human Exposure Study, Environmental Health, PM2.5
- Medical subject headings
- Asthma, Pulmonary Disease, Chronic Obstructive, Lung Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Woodsmoke (Lodgepole Pine) exposureOther
Woodsmoke will be freshly generated using a furnace tube burning dried, ground lodgepole pine (Pinus contorta) to achieve the nominal PM2.5 (particulate matter with an aerodynamic diameter of less than or equal to 2.5 micrometres) concentrations specified for each study arm.
Filtered air exposureOther
Exposures to HEPA filtered air, as a control.
| Study group | Role | What they receive |
|---|---|---|
| Arm A) Three repeated exposures to a low air pollution concentration | Experimental | Three consecutive days with a 2-hour woodsmoke exposure at 35 µg/m3 of PM2.5 each day. Receives: Other: Woodsmoke (Lodgepole Pine) exposure |
| Arm B) Three repeated exposures to a moderate air pollution concentration | Experimental | Three consecutive days with a 2-hour woodsmoke exposure at 105 µg/m3 of PM2.5 each day. Receives: Other: Woodsmoke (Lodgepole Pine) exposure |
| Arm C) Single exposure to a higher air pollution concentration | Experimental | Two consecutive days of 2-hour filtered air exposures, followed by 1 day with a 2-hour woodsmoke exposure at 315 µg/m3 of PM2.5. Receives: Other: Woodsmoke (Lodgepole Pine) exposure; Other: Filtered air exposure |
What is being measured
The primary outcome is the main question the study is designed to answer.
Effects of PM2.5 exposures and concentration on exhaled nitric oxide.
Measurement of fractional exhaled nitric oxide (FeNO).
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on Cambridge Neuropsychological Test Automated Battery (CANTAB)
Computational testing using CANTAB to determine e.g. 5-choice reaction time and percent correct all delays.
Measured: Comparison of the different arms over the span of 4 months.
Secondary outcomes (10)
Effects of PM2.5 exposures and concentration on sputum cell numbers.
Differentially count sputum cells.
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on brain functional connectivity.
Resting-state functional MRI (rs-fMRI) will assess functional connectivity within the default mode network (DMN) using a seed-based approach. Preprocessing will follow established neuroimaging methods. Functional connectivity will be determined as temporal correlations between blood-oxygen-level-dependent (BOLD) signal time series from a posterior cingulate cortex seed and DMN regions, using group-level statistical models.
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on oxidative stress.
Assessment of oxidative stress using H2DCFDA.
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on lung inflammatory markers.
An inflammation matrix will be generated, including data from RNA and protein inflammatory markers (e.g. interleukins (IL)-1ß, 4, 5, 6, 8, 9, 13, 17, 25 and 33, IFN., CSF1, TSLP, CC16/SCGB1A1 and c-reactive protein).
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on lung imaging.
The lungs will be imaged with hyperpolarized 129Xe gas to measure ventilation defect percent, membrane-to-gas ratio and red blood cell-to-gas ratio. These measures will be standardized and averaged to generate a single composite lung function imaging score per participant.
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on circulating brain-derived biomarkers of neuroinflammation.
Analysis of circulating brain-derived biomarkers of neuroinflammation using the NULISAseq CNS Diesease Panel 120.
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on neutrophil extracellular traps (NETs).
Analysis of counts of neutrophil extracellular traps (NETs).
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on host defence proteins.
Host defense peptides matrix, from e.g. alpha defensin-1, S100A7 and cystatin-SA.
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on DNA methylation.
Measurement of DNA methylation after exposures and determination of epigenetic age.
Measured: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on glia-derived extracellular vesicles.
Glia-derived extracellular vesicles will be measured in circulating blood using nanoflow cytometry-based direct labelling.
Measured: Comparison of the different arms over the span of 4 months.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Apr 2026
- Study start26 May 2026
- Primary completion31 Aug 2029 (estimated)
- Study completion31 Aug 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AsthmaStudies of the same condition, open and under way.
- More trials run by University of British ColumbiaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participants will act as their own controls, as they will complete all three study arms: Arm A) Three consecutive days with a 2-hour woodsmoke exposure at 35 µg/m3 of PM2.5 each day. Arm B) Three consecutive days with a 2-hour woodsmoke exposure at 105 µg/m3 of PM2.5 each day. Arm C) Two consecutive days of 2-hour filtered air exposures, followed by 1 day with a 2-hour woodsmoke exposure at 315 µg/m3 of PM2.5. The study arms will be separated by 4-week washout periods.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 24 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of British Columbia
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Christopher Carlsten, University of British Columbia
- Investigators
- Chris Carlsten, MD, MPH, Principal investigator, University of British Columbia
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07536178
- Sponsor's protocol ID
- H25-02833
- Other IDs
- LG3-193738, RFA 24-2
- Acronym
- LoF
- Status last verified
- May 2026
- First submitted
- 3 Apr 2026
- Last updated
- 26 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 26 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Lungs on Fire: Wildfire Smoke, Incident Diseases, Susceptible Populations, and Community Values in Canada
- ClinicalTrials.gov ID
- NCT07536178
- Acronym / sponsor ID
- LoF / H25-02833
- Keywords
- Wildfire Smoke, Chronic Lung Disease, Air Pollution, Controlled Human Exposure Study, Environmental Health, PM2.5
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 24 participants (estimated)
- Lead sponsor
- University of British ColumbiaUniversity, hospital or other
- Study start
- 26 May 2026 (actual)
- Primary completion
- 31 Aug 2029 (estimated)
- Study completion
- 31 Aug 2030 (estimated)
- First posted
- 17 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Wildfire smoke (WFS) is the leading climate-related risk in Canada and the main source of harmful air pollution. While short-term breathing problems caused by smoke are well known, there is limited knowledge on how repeated exposure contributes to long-term lung disease. This study is a controlled human exposure to varying concentrations of WFS in a safe setting. By comparing the effects of different concentrations, this research will improve understanding of health impacts, identify who may be most vulnerable to exposures, and explore biological changes that could lead to chronic illness.
Detailed description
PURPOSE: To use responses to controlled human exposures to woodsmoke, as a model of wildfire smoke (WFS), to quantify risk of, and add biological plausibility to, the supposition that WFS-related particulate matter with a diameter of 2.5 micrometers or less (PM2.5) contributes to the development of neurological and chronic lung diseases.
Study Exposure Arms:
Arm A: 3 consecutive days with 2h woodsmoke exposures at 35 µg/m3 of PM2.5 Arm B: 3 consecutive days with 2h woodsmoke exposures at 105 µg/m3 of PM2.5 Arm C: 2 consecutive days of Filtered Air (FA), followed by 1 day with a 2h woodsmoke exposure at 315 µg/m3 of PM2.5
HYPOTHESIS, JUSTIFICATIONS, AND OBJECTIVES Aim 1A: Enhance plausibility for, and quantify risk of, WFS contributions to chronic lung disease.
Hypothesis 1A: The investigators will determine mechanisms that plausibly link WFS exposure to the development of chronic disease, by connecting WFS exposures to lung function decline, asthma, chronic obstructive pulmonary disease (COPD), or lung cancer.
To assess the plausibility of linking WFS exposure to Chronic Lung Diseases such as asthma, COPD, and lung cancer.
To evaluate the biological impacts of WFS on the airways.
- Specifically, what are the effects of exposure concentration, intensity, and time on inflammatory and immunomodulatory responses to WFS exposure?
- Several biological pathways may link WFS exposures with the development of chronic respiratory diseases such as asthma, COPD, and lung cancer. These include effects of oxidative stress and inflammation on epithelial barrier integrity, which may facilitate contact with immune cells, allergen sensitization, increased infection susceptibility, and tissue remodelling that impairs lung function. Epigenetics, notably DNA methylation (DNAm), is another potential mechanism linking WFS to chronic disease, and the airway microbiome may also contribute through several pathways. However, WFS differs from general urban and traffic-related air pollution (TRAP), so effects of TRAP exposure demonstrated to date cannot be assumed to apply to WFS.
Aim 1B: Use a controlled human exposure study to identify, across different intensities of WFS exposure:
1.1 Neurocognitive changes relevant to the development of chronic neurological diseases 1.2 Temporal patterns of onset and resolution in relevant circulating neuro-inflammatory markers 1.3 Sex, age, and genetics as effect-modifying susceptibility factors for the above phenomena
Hypothesis 1B: The investigators will demonstrate disturbances in the brain default mode network (DMN), and intensity-dependent increases in circulating neuro-inflammatory markers, particularly in older individuals and those with genotypes conferring deficient anti-oxidant metabolism or those conferring risk of dementia.
RESEARCH DESIGN A randomized, double-blinded, crossover-controlled human exposure study.
STATISTICAL ANALYSIS Data will be analysed in R using generalized and linear mixed-effects models. Models will run with exposure as a fixed effect and participant ID as a random effect.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 3
- Model description
- Participants will act as their own controls, as they will complete all three study arms: Arm A) Three consecutive days with a 2-hour woodsmoke exposure at 35 µg/m3 of PM2.5 each day. Arm B) Three consecutive days with a 2-hour woodsmoke exposure at 105 µg/m3 of PM2.5 each day. Arm C) Two consecutive days of 2-hour filtered air exposures, followed by 1 day with a 2-hour woodsmoke exposure at 315 µg/m3 of PM2.5. The study arms will be separated by 4-week washout periods.
| Arm | Type | Receives |
|---|---|---|
| Arm A) Three repeated exposures to a low air pollution concentration | Experimental | Other: Woodsmoke (Lodgepole Pine) exposureThree consecutive days with a 2-hour woodsmoke exposure at 35 µg/m3 of PM2.5 each day. |
| Arm B) Three repeated exposures to a moderate air pollution concentration | Experimental | Other: Woodsmoke (Lodgepole Pine) exposureThree consecutive days with a 2-hour woodsmoke exposure at 105 µg/m3 of PM2.5 each day. |
| Arm C) Single exposure to a higher air pollution concentration | Experimental | Other: Woodsmoke (Lodgepole Pine) exposure, Other: Filtered air exposureTwo consecutive days of 2-hour filtered air exposures, followed by 1 day with a 2-hour woodsmoke exposure at 315 µg/m3 of PM2.5. |
Who may qualify
- Ages
- 19 to 80 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Healthy Adults between the ages of 19 to 80 (12 of each biological sex assigned at birth).
Key exclusion criteria (4 listed)
- Current smoker (within six months before screening; potential to confound exposure effects).
- History or current diagnosis of any respiratory conditions (including, but not limited to asthma or chronic obstructive pulmonary disease (COPD), asthma/COPD overlap) or other medical conditions that the study physician determines may impact participant safety.
- Any comorbidities or other concerns identified by the study physician which may impact study participation.
- For participants of child-bearing potential: Current pregnancy, or plans to become pregnant during study enrolment.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Woodsmoke (Lodgepole Pine) exposureWoodsmoke will be freshly generated using a furnace tube burning dried, ground lodgepole pine (Pinus contorta) to achieve the nominal PM2.5 (particulate matter with an aerodynamic diameter of less than or equal to 2.5 micrometres) concentrations specified for each study arm. | Other | Arm A) Three repeated exposures to a low air pollution concentration, Arm B) Three repeated exposures to a moderate air pollution concentration, Arm C) Single exposure to a higher air pollution concentration |
| Filtered air exposureExposures to HEPA filtered air, as a control. | Other | Arm C) Single exposure to a higher air pollution concentration |
Primary outcome
Effects of PM2.5 exposures and concentration on exhaled nitric oxide.
Time frame: Comparison of the different arms over the span of 4 months.
Measurement of fractional exhaled nitric oxide (FeNO).
Effects of PM2.5 exposures and concentration on Cambridge Neuropsychological Test Automated Battery (CANTAB)
Time frame: Comparison of the different arms over the span of 4 months.
Computational testing using CANTAB to determine e.g. 5-choice reaction time and percent correct all delays.
10 secondary outcomes
Effects of PM2.5 exposures and concentration on sputum cell numbers.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on brain functional connectivity.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on oxidative stress.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on lung inflammatory markers.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on lung imaging.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on circulating brain-derived biomarkers of neuroinflammation.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on neutrophil extracellular traps (NETs).
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on host defence proteins.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on DNA methylation.
Time frame: Comparison of the different arms over the span of 4 months.
Effects of PM2.5 exposures and concentration on glia-derived extracellular vesicles.
Time frame: Comparison of the different arms over the span of 4 months.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Oct 2026.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Chris Carlsten, MD, MPH principal investigator
University of British Columbia
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Woodsmoke (Lodgepole Pine) exposure and Filtered air exposure in people with Asthma and Chronic Obstructive Pulmonary Disease (COPD), run by University of British Columbia at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 26 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact PJ (Parteek) Johal, BCS (604-875-5132, p.johal@ubc.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Effects of PM2.5 exposures and concentration on exhaled nitric oxide. (time frame: Comparison of the different arms over the span of 4 months.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Oct 2026.