The BREATHE Study: Bronchiolitis Recovery and Use of HEPA Filters

Study Summary: Lay Summary for Participant Families

The BREATHE Study: Bronchiolitis Recovery and Use of HEPA Filters

Author(s): The BREATHE Study Team

Why was this study conducted?

Bronchiolitis is an infection that affects the airways of a child. Babies with bronchiolitis may need hospital treatment. These babies may still have breathing problems, such as coughing and wheezing, after they go home.

Many things can affect a person’s ability to breathe. One of those things is the level of very small particles in the air. These particles are called PM2.5, which are particulate matter that is less than 2.5 micrometers across. That size is smaller than the size of most pollen and mold. The level of these very small particles in the air in someone’s home can be lowered by special air filters called high efficiency particulate air (HEPA) filters.

The BREATHE study was done to find out if HEPA filters used in a baby’s house can help them breathe better than if no filter is used in their house. Specifically, the study looked at how many days infants, who previously had bronchiolitis, had specific breathing problems such as coughing, wheezing, or other breathing problems.

What was done?

Babies chosen for this study were less than 12 months old and had been hospitalized for bronchiolitis for the first time. Babies were selected from 17 hospitals, each in a different state. A total of 228 families were given either 2 HEPA units or 2 control units (identical units but with filters removed). One unit was to be used in the baby’s sleep space and the other unit in a common room of the home. Families did not know which types of units they were given. Air quality monitors measured the level of very small particles (PM2.5) in their homes. Families reported the number of days that their babies had breathing troubles. These reports were done weekly for 6 months. At the end of the study, families learned whether they had been using HEPA units or control units. All families were then given new HEPA filters. They also received individual reports about the PM2.5 levels in their home.

What was found?

The number of days babies had breathing problems were counted. The number of problem days for the babies living in homes with HEPA filters were compared to the number of problem days for the babies living in homes that had control units. Generally, babies in homes with working HEPA units had fewer breathing problems than babies in homes with the control units. Babies in homes with HEPA units had an average of 5 fewer days with breathing problems than did babies in homes with the control units. However, because the difference between the 2 groups is quite small, it is not clear if the breathing improvement was related to HEPA filter use or due to chance. This does not mean that the HEPA filters were not useful. It only means that it could not be proven with this study.

Compared to those with control units, babies who had HEPA filter units in their home had a 9% lower chance of unscheduled healthcare visits, such as hospitalizations, emergency room visits, and doctor’s office visits for breathing problems, but the difference between the 2 groups is small and may be due to chance. Babies who had HEPA filter units running most of the time during the study had a 25% lower chance of unscheduled doctor’s office visits for breathing problems.

On average, homes with working HEPA units had average common room PM2.5 equal to 11 micrograms per cubic meter (μg/m3). On average, levels were higher in the common room of homes with control units (15 μg/m3). The difference was even bigger in the infant’s sleep space. On average, homes with HEPA units had sleep space PM2.5 equal to 11 μg/m3. On average, homes with control units had sleep space PM2.5 equal to 21 μg/m3.

What do the results mean?

Filtering air with a HEPA unit may help infants who have been in the hospital for bronchiolitis. Infants in houses with HEPA units may have fewer days of breathing trouble than infants in houses without HEPA units. However, we would need to do a larger study to know for sure.

Who sponsored the study?

This research was supported by the Environmental influences on Child Health Outcomes (ECHO) program, the Office of the Director, National Institutes of Health.

Appreciation

The authors appreciate the children and families whose participation made the research possible.

The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Lay Summary for the BREATHE Study (for participant distribution)
cIRB # 274137 V-01 (27-October-2025)

BREATHE Study Achieves Recruitment Success for Infants with Bronchiolitis

Posted on September 19, 2024October 3, 2024 by Jodi Snare

The BREATHE (Bronchiolitis Recovery and the Use of HEPA Filters) study successfully reached its recruitment goal ahead of schedule and has maintained high participant retention with a 94.5% survey completion rate.

This clinical trial, part of the ECHO IDeA States Pediatric Clinical Trials Network (ISPCTN), focuses on airway health outcomes of infants hospitalized for bronchiolitis. The study, launched in November 2022 at 17 clinical sites across the country, aimed to recruit 230 children. In December 2023, study teams met their recruitment goal several months ahead of schedule and experienced successful retention over the past six months. ECHO ISPCTN anticipates sharing the primary results of this study in early 2025.

“Recruitment and retention successes are due to the hard work and dedication of each research study coordinator from the 17 sites,” said co-principal investigator Kelly Cowan, MD of the University of Vermont. “A big thank you goes out to these researchers as well as the families who agreed to participate, making a difference in children’s health outcomes.”

The goal of the BREATHE study is to determine whether using high-efficiency particulate air (HEPA) filters in the homes of infants under one year old, who were previously hospitalized for bronchiolitis, reduces symptom-free days from respiratory issues, such as cough or trouble breathing, in the six months after discharge.

Eligible families who consented to participate were randomly placed in an intervention or control group. The intervention group used HEPA units with active filters, and the control group used HEPA units with inactive filters. Caregivers agreed to place the HEPA units where the child slept and in a common space where the child spent a large amount of time. Small air pollution monitors were placed in those rooms to measure how the HEPA filters affected indoor air quality. At the conclusion of the study, all families were welcome to keep the HEPA unit(s) and were sent an individual report of their household’s indoor air quality during the study and a summary of the overall results.

Bronchiolitis, typically caused by a viral infection, is the most common cause of hospitalization in children younger than 2 years old in the U.S. Infants hospitalized for bronchiolitis face a higher risk of persistent respiratory symptoms and developing asthma. To date, no effective treatments have been identified.

Indoor air quality influences respiratory health and may be a promising target for intervention. Homes in rural and low-resourced communities often have greater exposure to sources of air pollution such as wood stoves and wildfires.

“If the intervention is successful, in-home HEPA air filtration would provide a strategy for improving breathing for many infants that will be relatively easy for families to implement,” explained co-principal investigator Erin Semmens, PhD of the University of Montana’s Center for Population Health Research.

Learn more about the BREATHE study.

ECHO Study Suggests Link Between Severe Bronchiolitis During Infancy and Asthma During Childhood

<< Back to Research Summaries

ECHO Study Suggests Link Between Severe Bronchiolitis During Infancy and Asthma During Childhood

Author(s): Kohei Hasegawa, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

What were the study results?

Bronchiolitis is a wheezing illness usually caused by a lung infection such as Respiratory Syncytial Virus (RSV). During this study, researchers found that the hospitalized infants with bronchiolitis were more likely to develop asthma by the age of 12 years when compared to hospitalized infant without bronchiolitis. The researchers also saw that this effect was stronger for non-Hispanic White and non-Hispanic Black infants, compared with Hispanic infants.

What was the study's impact?

This is the first nationwide investigation that demonstrates the role of severe bronchiolitis during infancy on influencing long-term childhood asthma risk and identifies subgroups of children who are most at risk for developing asthma following bronchiolitis during infancy. These results could help future investigations to identify what factors may influence the association between severe bronchiolitis and childhood asthma risk across different demographic groups, which could advance the development of targeted prevention strategies for childhood asthma.

Why was this study needed?

Severe bronchiolitis is the most common reason for hospitalization in U.S. infants younger than 2 years old. Many studies have shown that severe bronchiolitis, requiring hospitalization during infancy, is a risk factor for developing childhood asthma. However, these studies have been too narrow to evaluate how severe bronchiolitis during infancy affects childhood asthma risk in various demographic subgroups.

Who was involved?

The researchers analyzed data from 11,762 infants enrolled in 53 ECHO research sites across the United States. All of these infants were hospitalized at age 12 months or younger between 2001-2021. Of these infants, 10% were hospitalized with bronchiolitis. One of the participating ECHO cohorts selectively enrolled children with a parental history of asthma.

What happened during the study?

The researchers collected data from participating infants under 12 months old on caregiver-reported hospitalization for bronchiolitis. The researchers then used data on caregiver-reported asthma diagnosis prior to age 12 to evaluate the relationship between severe bronchiolitis and childhood asthma to determine how this relationship may be affected by major demographic and clinical factors.

Footnote: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What happens next?

Future studies are needed to investigate the reasons underlying the links among infant bronchiolitis, demographic and clinical factors, and the development of asthma. These findings not only provide an evidence base for early identification of children who are at high risk for asthma but also offer opportunities for early preventive interventions in this large, high-risk population.

Where can I learn more?

Access the full journal article, titled “Association of Severe Bronchiolitis during Infancy with Childhood Asthma Development: An Analysis of the ECHO Consortium,” in Biomedicines.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published: December 22, 2022

Download this summary

ECHO Study Suggests Link Between Severe Bronchiolitis During Infancy and Asthma During Childhood

ECHO

Environmental Influences on Child Health Outcomes

bronchiolitis

The BREATHE Study: Bronchiolitis Recovery and Use of HEPA Filters

Study Summary: Lay Summary for Participant Families