An irreversible loss in lung function limits the long-term success in lung transplantation. We evaluated the role of chronic exposure to ambient air pollution on lung function levels in lung transplant recipients (LTRs).The lung function of 520 LTRs from the Cohort in Lung Transplantation (COLT) study was measured every 6 months. The levels of air pollutants (nitrogen dioxide (NO javax.xml.bind.JAXBElement@45dc7659 ), particulate matter with an aerodynamic cut-off diameter of x µm (PM javax.xml.bind.JAXBElement@2c50353d ) and ozone (O javax.xml.bind.JAXBElement@1c0616d6 )) at the patients' home address were averaged in the 12 months before each spirometry test. The effects of air pollutants on forced expiratory volume in 1 s (FEV javax.xml.bind.JAXBElement@625c8a1e ) and forced vital capacity (FVC) in % predicted were estimated using mixed linear regressions. We assessed the effect modification of macrolide antibiotics in this relationship.Increased 12-month levels of pollutants were associated with lower levels of FVC % pred (-2.56%, 95% CI -3.86--1.25 for 5 µg·m javax.xml.bind.JAXBElement@449456b2 of PM javax.xml.bind.JAXBElement@69406ac0 ; -0.75%, 95% CI -1.38--0.12 for 2 µg·m javax.xml.bind.JAXBElement@455c6198 of PM javax.xml.bind.JAXBElement@43d61f57 and -2.58%, 95% CI -4.63--0.53 for 10 µg·m javax.xml.bind.JAXBElement@2591e059 of NO javax.xml.bind.JAXBElement@4f6d8841 ). In patients not taking macrolides, the deleterious association between PM and FVC tended to be stronger and PM javax.xml.bind.JAXBElement@699b7095 was associated with lower FEV javax.xml.bind.JAXBElement@1ac4e656 Our study suggests a deleterious effect of chronic exposure to air pollutants on lung function levels in LTRs, which might be modified with macrolides.