Effects of diesel exhaust on asthma treatment effectiveness

Diesel Exhaust Induces Glucocorticoid Resistance

Phase 4 Interventional University of British Columbia · NCT03615742

This study is testing how breathing in diesel exhaust affects the effectiveness of asthma medications in people with asthma.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment30 (estimated)
Ages19 Years to 49 Years
SexAll
SponsorUniversity of British Columbia Academic / other
Locations1 site (Vancouver, British Columbia)
Trial IDNCT03615742 on ClinicalTrials.gov

What this trial studies

This study investigates how exposure to diesel exhaust affects lung inflammation and the effectiveness of inhaled corticosteroids in individuals with asthma. Participants will inhale either a placebo or a corticosteroid before being exposed to either filtered air or diluted diesel exhaust for two hours. The study aims to analyze the impact of diesel exhaust on gene expression related to inflammation and corticosteroid response. By understanding the mechanisms behind glucocorticoid resistance in the context of air pollution, the research seeks to inform better treatment guidelines for asthmatics.

Who should consider this trial

Good fit: Ideal candidates for this study are adults aged 19-49 with physician-diagnosed asthma and specific lung function criteria.

Not a fit: Patients who smoke, are currently using corticosteroids, or have significant comorbidities may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to improved treatment strategies for asthma patients exposed to air pollution, potentially reducing exacerbations and enhancing quality of life.

How similar studies have performed: While there is correlational data regarding air pollution and corticosteroid use in asthmatics, this study represents a novel approach to directly assess the effects of diesel exhaust on corticosteroid effectiveness.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Aged 19-49
2. Have physician-diagnosed asthma confirmed by the study physician examination, spirometry, methacholine challenge provocative concentration causing a 20% fall (PC20) of \<16 mg/mL, and questionnaires during a screening visit

Exclusion Criteria:

1. Smoking of any kind (0.5 pack-years ever, or any current) or use of vape/vaporizing devices
2. Regular anti-histamine, NSAID, corticosteroid or other controller medication use
3. Pregnancy or breastfeeding
4. Methacholine PC20 \>16
5. Relevant cardiac condition or arrhythmia
6. Body mass index of \>35
7. Currently participating in another study that may interfere with this study
8. Use of either inhaled or oral corticosteroids in preceding 6 months
9. Substantial comorbidities on study physician's examination or other concerns
10. Surgery scheduled before anticipated study completion

Where this trial is running

Vancouver, British Columbia

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Exposure to PollutionGlucocorticoid ResistanceDiesel ExhaustAir PollutionInhaled CorticosteroidsGene ExpressionAsthmaControlled Human Exposure Study
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.