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

Bronchopulmonary dysplasia (BPD) is the most common morbidity of preterm birth, affecting up to 50 000 infants each year in the USA.1 Fine particulate matter <2.5 µm in diameter (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 neonatal intensive care unit (NICU) discharge.2 The Environmental Protection Agency recently lowered the level of the health-based standard of annual average PM2.5 exposure from 12 to 9 μg/m3. 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