Double masking has limited effects: Japan team

Simulations by Japan’s Fugaku supercomputer showed that wearing two face masks has more or less the same effects as wearing a well-fitting non-woven mask in reducing the spread of droplets, said a team led by researchers at the government-affiliated Riken institute, On thursday.

“It is important to wear a single mask made of non-woven fabric properly,” said the team, led by Makoto Tsubokura, a professor at the University of Kobe.

The team simulated effects to contain the spread of droplets when a non-woven mask is used securely using a nasal bridge or when used wirelessly.

When a mask fits well, 85% of the drops are contained, with the effects dropping to 69% in an ill-fitting mask, the team said.

When a poorly adjusted non-woven mask is covered by a urethane mask, the reduction effects reach 89%, almost equivalent to a single non-woven mask with good fit, according to the simulations.

“Masks have limits on their effects to contain the spread of droplets,” said Tsubokura. “It is important to take action against infectious diseases comprehensively, including washing your hands, ensuring ventilation, maintaining social distance and limiting the duration of contacts with other people,” he said.

For people who want to wear two masks to prevent skin damage, Tsubokura recommends using a tighter mask on the inside.

Tsubokura also said that the drops spread widely behind a person when they are moving, such as walking or running. He added that if an infected person speaks while on an escalator, there is an increased risk of infected people.

The U.S. Centers for Disease Control and Prevention said last month that putting a cloth mask over a medical procedure mask – and knotting the handles of a medical procedure mask and then attaching and straightening the extra material close to the face – substantially reduced the exposure of infected users and exposure of uninfected users, highlighting the importance of a good fit to maximize the effectiveness of the mask.