Air Pollution, Asthma and Circadian Clocks
Public ClinicalTrials.gov record NCT03406351. Field values are reproduced from the official study page; the official ClinicalTrials.gov record remains the source of truth for eligibility, enrollment, and contact information.
Data is sourced from official ClinicalTrials.gov public API records. Always review the official ClinicalTrials.gov record for the latest information.
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
Societies become increasingly urban - more than half the world's population now lives in cities. Urbanization elevates anthropogenic (man-made) exposure to air pollutants. A clear association exists between exposure to air pollutants and exacerbations (worsening) of pre-existing asthma, incidence of nighttime asthma, difficulties with asthma control and increased disease risk. In 2012, the Public Health Management Corporation's Community Health Data Base estimated that 19.4% of adults in Philadelphia had asthma compared to a national prevalence of 7%. Asthma has a clear temporal signal. A majority of asthma patients, up to 75%, reports nighttime awakenings due to worsened cough, wheeze and dyspnea. This time-of-day-dependent exacerbation of symptoms, coined nocturnal asthma, is associated with poorer disease control, more frequent medication, and higher asthma-related morbidity and mortality. Consequently, several pathophysiological mechanisms proposed for nocturnal asthma relate to circadian clock biology. Lung function oscillates over the course of 24 hours, peaking around noon and reaching its nadir during early morning hours. Concentrations of air pollutants show oscillating patterns in urban settings. In this clinical research study, the investigators start to address how spatiotemporal fluctuations in air pollutants relate to asthma. Mechanistically, the investigators wish to address the hypothesis that microRNAs (miRs) act as interface between asthma phenotypes, circadian clocks and environmental exposure.
Study identification
- NCT ID
- NCT03406351
- Recruitment status
- Active, not recruiting
- Study type
- Observational
- Phase
- Not listed
- Enrollment
- 20 participants
Conditions and interventions
Eligibility (public fields only)
- Age range
- 18 Years to 70 Years
- Sex
- All
- Healthy volunteers
- Accepts healthy volunteers
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Jan 14, 2018
- Primary completion
- Dec 31, 2026
- Completion
- Dec 31, 2027
- Last update posted
- Jan 22, 2026
2018 – 2028
United States locations
- U.S. sites
- 1
- U.S. states
- 1
- U.S. cities
- 1
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| University of Pennsylvania School of Medicine | Philadelphia | Pennsylvania | 19104 | — |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT03406351, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Jan 22, 2026 · Synced Sep 8, 2026
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Open the official record
The complete protocol, eligibility criteria, and contact information for NCT03406351 live on ClinicalTrials.gov.