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The

coronavirus

pandemic

has brought with it, among many other things, masks and social distancing.

The masks to avoid

contagion

by droplets of saliva, social distancing so that these particles do not become contagious.

So far, along with hand washing, they have been the protection measures par excellence.

However, a Japanese study published in the scientific journal Physics of Fluids has shown that there is not so much protection.

A simple conversation between two close people with or without a mask, such as that which occurs in a hairdresser or dental office, can transmit the

coronavirus

.

It is known that the coronavirus can spread between infected people, even if they do not show symptoms, through the

tiny drops in the air that they breathe out

, and most studies have focused on what happens when the person coughs or sneezes and the drops are expelled Long distance.

Now, a team of researchers led by

Keiko Ishii

from the Department of Mechanical Engineering at Japan's Aoyama Gakuin University has used the smoke generated by e-cigarettes and laser light in observing the flow of breath near and around two people conversing. in various postures.

The study focuses especially on the positions that people acquire when communicating in

hairdressing salons

,

medical examination rooms

or

residences

where sick or elderly people receive care.

To simulate the droplets of saliva that are exhaled when speaking, the researchers turned to e-cigarettes that produce a vapor with droplets with a diameter of around one tenth of a micron, similar to a

coronavirus

particle

.

The liquid used in these

vaporization devices

consisted of a mixture of glycerin and propylene glycol that produces a cloud of droplets that reflect the light of a laser, which allows the visualization of the air flows.

The researchers analyzed the diffusion of exhalation with or without a mask when a person is

standing, sitting or lying on their back

.

The results are surprising, as tests showed that the air exhaled by a person without a mask while speaking moves downward under the influence of gravity.

Image of the transmission of particles when speaking.Physics of Fluids

If a client or patient is underneath, they can be infected.When wearing a mask while standing or sitting,

the vapor cloud tends to adhere to the body

of this person who has a higher temperature than the environment and the air flows upwards.

However, if the hairdresser or nurse leans forward, the drops tend to detach from that person's body and fall on the client or patient below.

The experiments were carried out in the hairdresser of

the Yamano College of Aesthetics

, in Tokyo, with postures typical of personal service situations, such as when the client leans back to have their hair washed and the hairdresser is standing, leaning forward.

The study was also carried out with face masks, reaching the conclusion that the use of these can prevent the aerosol that escapes from the mask of the hairdresser or the nurse from being transferred to the client.

"The face shield promotes the rise of exhaled air

,

"

says Ishii.

"And therefore the use of a mask and face shield is more effective when providing customer service."

According to the criteria of The Trust Project

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