Researchers in Japan say they have confirmed that face masks are effective in both retarding the spread of viruses and reducing the intake of them.

They used actual coronaviruses and mannequins to reach that conclusion.

The finding was made by a group led by Professor Kawaoka Yoshihiro and Project Assistant Professor Ueki Hiroshi at the University of Tokyo's Institute of Medical Science.

In their experiments, they placed two mannequins face-to-face in a laboratory. One was designed to discharge airborne droplets containing the coronaviruses. The other had a mechanism enabling it to take in air, imitating human breathing.

In one experiment, the researchers put a mask on the inhaling mannequin. They say the amount of viruses it absorbed was cut by 17 percent with a cloth mask and by 47 percent with an ordinary surgical mask. When they put an N95 medical mask on the mannequin so it fitted snugly, the amount declined by 79 percent.

When a mask was put on the virus-spreading mannequin, both cloth and surgical masks reduced the other, non-mask-wearing mannequin's intake of viruses by more than 70 percent.

The researchers also report that putting masks on both mannequins could not completely prevent the transmission of viruses.

Professor Kawaoka said there previously had been no research demonstrating masks' effectiveness using real viruses. The professor also said they confirmed it is important that masks are worn properly.

He added it is important to be aware that masks cannot block viruses completely.