Learn more about the BREATHE study HERE.
This study is completed.

The BREATHE (Bronchiolitis Recovery and the Use of HEPA Filters) study, conducted in 17 clinical sites across the United States, has successfully concluded after recruiting 230 infants who suffered from bronchiolitis facing a higher risk of persistent respiratory symptoms and developing asthma.

The study, part of the ECHO Program IDeA States Pediatric Network (ISPCTN), was designed and led by Drs. Erin O. Semmens, PhD, MPH from the University of Montana and Kelly Cowan, MD from the University of Vermont. The study focused on airway health outcomes and enrolled Infants <12 months of age from non-smoking households and hospitalized for the first time with bronchiolitis between November 2022 and December 2023. Study activities ended in July 2024 with successful participant retention and a 94.5% survey completion rate.

The overall study goal was 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, would reduce symptom-free days from respiratory issues, such as cough or trouble breathing, in the six months after discharge. 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.

Eligible families who consented to participate were randomly placed in an intervention or control group; 228 infants were randomized 1:1 to use either two functioning HEPA units or two placebo units for 24 weeks. 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.

The primary objective was to determine if use of a HEPA filtration home intervention reduces the respiratory symptom burden for 24 weeks compared to a use of an inactive filter. The primary endpoint was the number of caregiver-reported symptom-free days in a weekly survey, defined as a 24-hour period without coughing, wheezing, or trouble breathing. Secondary objectives were to test efficacy of a HEPA filtration home intervention, relative to control, on the number of caregiver-reported unscheduled healthcare visits for respiratory symptoms over 24 weeks; parent-reported quality of life measures; and mean weekly fine particulate matter (PM_2.5) levels in the home over 24 weeks.

“Indoor air quality affects respiratory health. Homes in rural and low resourced communities often have greater exposure to sources of air pollution such as wood stoves, and more and more homes are in wildfire-impacted communities,” explains Erin Semmens, PhD of the University of Montana’s Center for Population Health Research. “The families that participated in BREATHE and the study team did a remarkable job carrying out this work. Final data analyses are underway, and we look forward to sharing whether HEPA filtration is an effective strategy for improving infant health after bronchiolitis.”

At the conclusion of the study, all families received replacement filters and kept the HEPA unit(s). Families received an individual report of their household’s indoor air quality during the study and will also receive a summary of the overall results.