Bacterial air filters.
D000769:Anesthesia, Inhalation / Q000295:instrumentation*; D001419:Bacteria; D001424:Bacterial Infections / Q000209:etiology / Q000517:prevention & control*; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D011014:Pneumonia / Q000517:prevention & control*; D011183:Postoperative Complications / Q000517:prevention & control*