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Everyday ozone may harm asthma sufferers more than thought

NCT ID NCT04109807

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused This study
Paused for now. It may or may not start again.
Ongoing
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study looks at how breathing in low levels of ozone—similar to what you might encounter on a typical day in Chapel Hill—affects lung function and airway inflammation in adults with mild asthma. Researchers will compare ozone exposure to filtered air in 18 participants. The goal is to see if even small amounts of ozone can cause breathing problems or inflammation.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
ozone exposure
What this could lead to
If successful, this could help understand how everyday ozone levels impact people with asthma, potentially guiding air quality recommendations.
What could go wrong
This is a small, early-phase study with only 18 participants, so results may not apply broadly. The trial is currently suspended, which may delay findings.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Not a phased trial

Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.

Participants

About 18 people

The number the study aims to enrol. It can still change while the study runs.

Started

Dec 2019

Expected to finish

Aug 2027

An estimate. End dates often move.

Lead sponsor

Other sponsor

The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 to 45 years

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Ages 18-45, both sexes included * Mild intermittent asthma, defined as daytime asthma symptoms no more than 2 times per week, night time asthma symptoms no more than 2 times per month, FEV1 \>80% of predicted, and asthma exacerbation requiring oral steroids 1 time or less per year. * Good general health as evidenced by medical history * Vital signs will be within normal limits on admission to the study: oxygen saturation by pulse oximetry (SpO2) \> 94%, systolic blood pressure between 150-90 mm Hg, diastolic blood pressure between 100-60 mm Hg, afebrile. * FEV1 of at least 80% of predicted at baseline * Able to provide informed consent * Proof of Covid Vaccination Exclusion Criteria: * Any chronic medical condition considered by the PI as a contraindication to the exposure study including significant cardiovascular disease, diabetes, chronic renal disease, chronic thyroid disease, history of chronic infections/immunodeficiency, history of tuberculosis * Physician directed emergency treatment for an asthma exacerbation within the preceding 12 months * Orthopedic injuries or impediments that would preclude bicycle or treadmill exercise * Viral upper respiratory tract infection within 4 weeks of challenge. * Any acute infection requiring antibiotics within 4 weeks of exposure or fever of unknown origin within 2 weeks of challenge. * Individuals who use daily controller medication for asthma. Pre-treatment with a short acting bronchodilator prior to exercise is allowed. * Nasal surgery within 6 months * Mental illness or history of drug or alcohol abuse that, in the opinion of the investigator, would interfere with the participant's ability to comply with study requirements. * Any recent or current use of nicotine * History of intubation for asthma * Pregnancy or nursing an infant as EPA strictly prohibits intentional exposure for research to this population. * Covid infection in the past 90 days

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Conditions

The condition(s) this trial relates to.

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

How to take part

Only the study team decides who joins. These are the ways to reach them.

  1. The places running it

    1 site. The list below names each one and where it is.

  2. The official record

    The full official record for this study. This one lists no contact details, but it is the first place any would appear.

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  3. A doctor treating you

    A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.

Contacts and locations

Locations

  • University of North Carolina CEMALB

    Chapel Hill, North Carolina, 27599, United States

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