Expiratory bacterial filters.
D000391:Air Microbiology; D005374:Filtration / Q000295:instrumentation*; D010357:Patient Isolators / Q000295:instrumentation; D011482:Protective Devices / Q000592:standards*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D012134:Respiratory Protective Devices / Q000592:standards*; D012706:Serratia marcescens / Q000302:isolation & purification