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. Author manuscript; available in PMC: 2026 Aug 19.
Published in final edited form as: Arch Dis Child Fetal Neonatal Ed. 2025 Aug 19;110(5):521–522. doi: 10.1136/archdischild-2025-328533

Modeling the association of reduction in PM2.5 with medically attended acute respiratory illness in infants with mild bronchopulmonary dysplasia

Timothy D Nelin a,b,c, Joshua K Radack a, Sara B DeMauro a, Nicolas P Goldstein Novick a, Kristan Scott a, Allan C Just d, Heather H Burris a,b,c
PMCID: PMC12353573  NIHMSID: NIHMS2080286  PMID: 40274379

Bronchopulmonary dysplasia (BPD) is the most common morbidity of preterm birth, affecting up to 50,000 infants each year in the United States.1 Fine particulate matter (PM2.5) is a measure of air pollution and our team recently reported that among infants diagnosed with grade 1 BPD (≤2 L/min nasal cannula at 36 weeks postmenstrual age) and discharged from a Philadelphia hospital system, each 1 μg/m3 increment of PM2.5 was associated with 65% higher odds of medically attended acute respiratory illness in the first year after NICU discharge.2 The Environmental Protection Agency (EPA) recently lowered the level of the health-based standard of annual average PM2.5 exposure from 12 to 9 μg/m.3 While a concentration-response association has been identified of PM2.5 with mortality, chronic obstructive pulmonary disease, and asthma medication use in adults, the policy-relevant impact of reducing PM2.5 exposure among infants with BPD remains unknown.3–5

Using the same dataset as our prior study,2 we modeled the average marginal effects (AME) of decreasing annual mean PM2.5 exposure by 1 μg/m3 with medically attended acute respiratory illness (emergency department [ED] visits or inpatient admissions) in the first year after NICU discharge among infants with grade 1 BPD to simulate the adjusted rates of medically attended acute respiratory illness per 1 μg/m3 decrease in annual PM2.5 concentration.6 We used unadjusted and adjusted models for age at NICU discharge, year, sex, race/ethnicity, insurance status, and census tract neighborhood deprivation.7 We chose the material community deprivation index to quantify census tract neighborhood deprivation as it includes variables related to economic status, education, housing and environment, and insurance status while not including race or ethnicity.8 Secondary analyses evaluated ED visits and admissions separately. As insurance payor may influence ability to access care and type of care accessed, we performed a subgroup analysis of public versus privately insured infants. This research was approved by the Institutional Review Board of the Children’s Hospital of Philadelphia.

Table 1 displays characteristics of 127 infants with grade 1 BPD. Unadjusted and adjusted models demonstrated that a 1 μg/m3 reduction in PM2.5 could potentially lead to 11.0% (95% CI: 4.6, 17.3) and 9.6% (95% CI: 1.7, 17.5) decreases in medically attended acute respiratory illness, respectively (Figure 1). In the subgroup analysis, models demonstrated that a 1 μg/m3 reduction in PM2.5 was associated with a 9.6% (95% CI: −4.4, 23.5) and an 8.1% (95% CI: −6.2, 22.4) decrease in medically attended acute respiratory illness for publicly and privately insured infants, respectively.

Table 1.

Bivariate associations of characteristics with medically attended acute respiratory illness (ED visit or hospital admission) in the first year after NICU discharge among infants <32 weeks’ gestation with grade 1 BPDa

Characteristic (n = 127) No Medically Attended Acute Respiratory Illness (n=85) Medically Attended Acute Respiratory Illness (n=42) p-value
Gestational age (weeks), mean (SD) 27 (2) 27 (2) 0.330
Birth weight (grams), mean (SD)b 857 (301) 889 (334) 0.590
Discharge age (days), mean (SD) 113 (49) 121 (62) 0.390
Female sex, n (%) 34 (40) 15 (36) 0.640
Infant race, n (%) 0.015
 Black 33 (39) 26 (62)
 White 32 (38) 6 (14)
 Other 20 (24) 10 (24)
Hispanic ethnicity, n (%) 9 (11) 7 (17) 0.333
Public insurance, n (%) 45 (53) 29 (69) 0.083
Census tract deprivation quartile, n (%)c 0.018
 1 (Lowest) 26 (31) 3 (7)
 2 17 (20) 8 (19)
 3 19 (22) 16 (38)
 4 (Highest) 23 (27) 15 (36)
PM2.5 concentration (μg/m3), mean (SD)d 8.74 (1.03) 9.33 (1.02) 0.003
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Abbreviations: ED, emergency department; BPD, bronchopulmonary dysplasia; NICU, neonatal intensive care unit; SD, standard deviation; PM2.5, particulate matter <2.5μm in diameter

Two-way t-test used for continuous variables. Chi-square used for categorical variables.

a

BPD severity assessed at 36 weeks or hospital admission if hospital admission to CHOP occurred after 36 weeks post menstrual age using 2019 NRN criteria (Jensen et al. 2019).

b

Missing data: birth weight (n = 1).

c

Census tract-level Deprivation Index from 2018 (Brokamp et al. 2019).

d

Mean PM2.5 ambient concentrations in the year after NICU discharge.

Figure 1.

Figure 1

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Adjusted average marginal effects (AME) of reducing particulate matter <2.5 μm in diameter (PM2.5) exposure by 1 μg/m3 with medically attended acute respiratory illness in the first year after neonatal intensive care unit (NICU) discharge among preterm infants with grade 1 bronchopulmonary dysplasia. Model was adjusted for age at NICU discharge, year, sex, race/ethnicity, insurance status and census tract neighbourhood deprivation. Per 1 μg/m3 decrease in PM2.5, there was a 9.6% (95% CI: 1.7% to 17.5%) decrease in medically attended acute respiratory illness, 5.6% (95% CI: 0.6% to 10.5%) decrease in emergency department visits and 3.7% (95% CI: −4.0% to 11.5%) decrease in inpatient admission.

Environmental policies, such as the Clean Air Act, have contributed to a substantial decrease in air pollution, specifically PM2.5, in the US over the past 20 years.9 Quantifying the health benefits of such policies is important to motivate ongoing environmental improvements. While the effect may seem small, it only represents potential impact in the first year after NICU discharge. It is possible that there may be an effect throughout childhood of life in this vulnerable population.

Our model used estimates from a single-center study in one US metropolitan area and thus the exact numbers of avoidable acute respiratory illnesses may differ if the model does not generalize to all settings. Nonetheless, even small reductions in PM2.5 concentrations may improve the health of hundreds of preterm infants with grade 1 BPD each year in the US.

Funding/Support:

All phases of this study were supported by a NIEHS Pilot Grant from the Philadelphia Regional Center for Children’s Environmental Health (P2CES033428), a T32 award from the NIH (T32HL160493), and a Marshall Klaus Award from the American Academy of Pediatrics Section on Neonatal Perinatal Medicine (SONPM).

Role of Funder/Sponsor (if any):

The NIH and AAP had no role in the design and conduct of the study.

Abbreviations:

AME

average marginal effects

BPD

bronchopulmonary dysplasia

ED

emergency department

EHR

electronic health record

NICU

neonatal intensive care unit

PM2.5

particulate matter < 2.5 μm in diameter

SD

standard deviation

WHO

World Health Organization

Footnotes

Competing Interests: None declared

References

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