rccm1818eds 769..772 The evidence is both epidemiological and biological. The study by Fell and colleagues in this .... Korfei M, Ruppert C, Mahavadi P, Henneke I, Markart P, Koch M, ... AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE VOL 181 2010. http://ajrccm.atsjournals.org/cgi/reprint/181/8/771.pdf