Al-Kindi SG, Sarode A, Zullo M, et al. - Researchers examined the link between PM_2.5 exposure and mortality post-heart transplantation. From the United Network for Organ Sharing (UNOS) database, they obtained mortality data in patients who had heart transplantation (2004 to 2015). Based on the zip code of residence, they linked these data with confirmed estimates of fine particulate matter concentrations for each calendar year during which a UNOS cardiac transplant recipient was at risk for death. Overall 21,800 patients were included, with 86,713 patient-years of follow-up. Per 10 μg/m³ increment rise in annual PM_2.5 exposure, the estimated mortality hazard ratio was 1.43. The estimated death hazard ratio per 10 μg/m³ increment in annual exposure to PM_2.5 was 1.26 relative rise in hazard of mortality, following adjustment for 30 recipient, donor, and neighborhood variables. This link was found to be consistent across subgroups. A connection between air pollution and mortality post-heart transplantation was evident in this study. A crucial impact of air pollution on outcomes after heart transplantation was suggested.