Research In Practice Blog
Among infants born extremely preterm, Bronchopulmonary dysplasia (BPD) represents the most prevalent chronic complication, affecting approximately half of survivors. BPD is a chronic lung disease that affects infants born premature with respiratory distress syndrome (RDS). Most infants who develop BPD are born more than 10 weeks before their due dates, weigh less than 2 pounds at birth, and have breathing difficulties. Nearly half of infants with BPD require hospital readmission for respiratory illnesses within their first year after being discharged. These children have an increased chance of life-long adverse respiratory outcomes including recurrent wheezing, respiratory infections, and asthma
“These infants often spend months in the NICU, and it is important that once these patients are eligible for discharge, families have the latest information and tools to keep them as safe as possible from further respiratory issues,” said Heather H. Burris, MD, MPH, an attending neonatologist at Children’s Hospital of Philadelphia Newborn Care and the Hospital of the University of Pennsylvania and Children's Hospital of Philadelphia (CHOP) and a core faculty member at Clinical Futures.
Exposure to ambient air pollution during critical development windows can lead to long-term respiratory risks in children. For children in the NICU, this risk is even greater. Lungs of preterm infants can exhibit limited alveolarization, dysregulated angiogenesis, and heightened oxidative stress. Ultrafine and fine particles penetrate distal airways, generate reactive oxygen species, and amplify Th2‑skewed inflammation, pathways that are already primed in infants with BPD.
Researchers, including Clinical Futures experts, Drs. Kristan A Scott, Scott A Lorch, Chén C Kenyon, and Heather H Burris were part of a recently published new study exploring whether exposure to fine particulate matter with an aerodynamic diameter of ≤ 2.5 µm (PM2.5) during the first year after NICU care is associated with asthma by age 5 among infants with bronchopulmonary dysplasia (BPD). The study titled ‘Associations of Early Life Ambient PM2.5 Exposure With Asthma Risk in a Cohort of Preterm Infants With Bronchopulmonary Dysplasia’ included investigators from the University of Pennsylvania, Children's Hospital of Philadelphia (CHOP), University of Vermont, Harvard Medicine School, and Brown University. Investigators from the University of Pennsylvania were the recipients of NIH funding for this study.
“For this vulnerable population, understanding the role of environmental exposures during critical developmental windows are essential for developing future strategies that can decrease the long-term respiratory risks for these children” said Tim Nelin, MD MSHP, an attending physician in the Division of Neonatology at Children's Hospital of Philadelphia.
Study Design and Findings
This retrospective cohort study, included 337 infants with BPD, born between 2010 and 2019. Participants received neonatal care within the CHOP Care Network through age 5. CHOP maintains over 30 pediatric primary care practices and over 15 specialty care and surgery centers throughout Pennsylvania and New Jersey. Infants were included, if they received any type of care, including primary care, subspecialty care, acute care (e.g., urgent care or emergency department), or inpatient care at any CHOP-affiliated site through age five. This allowed sufficient follow-up time to capture asthma diagnoses within the EHR reliably.
Residential data was used to estimate post-discharge ambient air pollutant exposure at the census block group level. Daily predictions of PM2.5 exposure were averaged over the first 12 months following NICU discharge. These predictions were generated using an XIS model that integrates satellite aerosol optical depth with meteorological, land use, and topographical data.
By age 5 years, 169 (50.1%) had received an asthma diagnosis. Each 1 µg/m³ increase in PM2.5 exposure was associated with higher risk of developing asthma. The mean annual PM2.5 exposure was measured at 8.8 µg/m³. When comparing exposure levels, adjusted risk of asthma was higher in those with exposure in the highest tertile (mean 10 µg/m³) compared to the lowest tertile (mean 7.6 µg/m³).
Improved Air Quality for Healthier Lungs
Exposure to higher levels of fine particulate matter during the first 12 months after NICU discharge was associated with asthma diagnosis by the age 5 for children with BPD. These particles can contribute to wheeze, respiratory deficits, and asthma in infants born preterm.
“Children with BPD have compromised lung function and are at increased risk of experiencing breathing difficulties from air pollution. These findings highlight that early-life air quality is a modifiable factor that can influence long-term respiratory outcomes in infants with BPD,” said Kristan A Scott, a neonatologist at CHOP, and a postdoctoral fellow in the National Clinician Scholars Program at the Perelman School of Medicine at the University of Pennsylvania, said.
Even small reductions in exposure to fine particles may provide long-term respiratory benefits for children with BPD. Implementing environmental modifications or enacting changes in air quality laws to decrease the number of ambient particles in the air can improve the long-term quality of life for children born with BPD. Since environmental exposures can be modified through personal mitigation and policy changes, these findings hold significant implications for creating targeted interventions aimed at enhancing long-term health outcomes in children with bronchopulmonary dysplasia.
Clinical Futures author(s): Kristan A Scott, Scott A Lorch, Chén C Kenyon, Heather H Burris
Citation: L. F. Gomez, J. J. Szeto, J. K. Radack, et al., “Associations of Early Life Ambient PM2.5 Exposure With Asthma Risk in a Cohort of Preterm Infants With Bronchopulmonary Dysplasia,” Pediatric Pulmonology 60 (2025): 1-9. https://doi.org/10.1002/ppul.71432.