Poorly fitted respirator bad as loose mask WASHINGTON, March 31 (UPI) -- A poorly fitted respirator performs no better than a loosely fitting surgical mask against influenza germs, U.S. and Chinese researchers said. John D. Noti of the National Institute for Occupational Safety and Health, part of the Centers for Disease Control and Prevention, said the potential for aerosol transmission of infectious influenza virus such as in healthcare facilities or a doctor's waiting room is controversial. "We constructed a simulated patient examination room that contained coughing and breathing manikins to determine whether coughed influenza was infectious and assessed the effectiveness of an N95 respirator and surgical mask in blocking transmission," Noti said in a statement. National Institute for Occupational Safety and Health collected size-fractionated aerosols for 60 minutes at the mouth of the breathing manikin, beside the mouth, and at three other locations in the room, the researchers said. The study published in Clinical Infectious Diseases found infectious influenza was recovered in all aerosol fractions (sizes), but tightly sealing a mask to the face blocked entry of 94.5 percent of total virus and 94.8 percent of infectious virus. The study also found a slightly sealed respirator blocked 99.8 percent of total virus and 99.6 percent of infectious virus, but a poorly fitted respirator blocked 64.5 percent of total virus and 66.5 percent of infectious virus. A mask documented to be loosely fitting -- to simulate how masks are worn by healthcare workers -- blocked entry of 68.5 percent of total virus and 56.6 percent of infectious virus.