RT Journal Article SR Electronic T1 Respirators evaluated by fit testing JF ERJ Open Research JO erjor FD European Respiratory Society SP 00581-2020 DO 10.1183/23120541.00581-2020 VO 6 IS 4 A1 Lukas Kleinjohann A1 Christoph Lange YR 2020 UL http://openres.ersjournals.com/content/6/4/00581-2020.abstract AB