The Impact of Air Pollution on Frequent Exacerbations among COPD Patients: An Observational Study on the Population of Western Romania. - Bălă, Gabriel-Petrică; Timar, Bogdan; Gorun, Florin; Motisan, Radu; Pescaru, Camelia; Tudorache, Emanuela; Marc, Monica; Manolescu, Diana; Citu, Cosmin; Oancea, Cristian (Journal of Clinical Medicine, 2022)