Face shields are no substitute for masks: Tribune India

Pushpagiri Maji

How effective are the plastic face shields available on the market in preventing the spread of the coronavirus? Some of my colleagues at work wear these instead of masks with the excuse that the masks are choking, especially if they have been worn for long periods of time.

Masks are certainly unpleasant, but experts do not recommend facial shields as an alternative to masks. They can only be used as an additional precaution with masks.

As mentioned earlier, a good plastic face shield protects the wearer and others if Covid-19 was thought to spread primarily through large breathing droplets emitted from the infected person’s nose and mouth. It was thought to be very effective in doing so. Some scientists even claimed that it was superior to masks in blocking respiratory droplets. In addition, it covered the wearer’s eyes, reduced exposure to the virus and prevented the wearer from touching the face with contaminated hands.

However, as evidence of aerial transmission of the disease is increasing, the gap between the visor and the skin near the chin and ears causes the virus-carrying aerosol or microscopic respiratory droplets to wear asymptomatic infected. There is concern that you can escape from the person. Infects nearby people. Gap can also expose the wearer to the virus.

In some countries that recommend or allow face shields instead of masks, the position is currently changing. For example, in June, Singapore stated that the Covid-19 Task Force concluded that shields were not as effective as masks. Similarly, in July Swiss health officials warned citizens not to use face shields, saying they gave the wearer a false sense of security.

According to media reports, the warning was issued after the outbreak of Covid-19 at a hotel in the Graubünden region, where a hotel employee wearing a face shield was infected and a hotel employee wearing a mask It turned out to be saved. The US Centers for Disease Control and Prevention also says there is not enough evidence of the level of protection that facial shields provide to nearby people from the spray of breathing droplets from the wearer.

A recent study on the topic of the Journal Physics of Fluids, published by the U.S. Institute of Physics on September 1, does not recommend the use of facial shields (and masks with exhalation valves) and is widely used. , Covid-19 Mitigation efforts.

Face masks score higher than shields now, or until vice versa, but also with social distance and hand hygiene. All three are very important precautions to take one.

Can face masks prevent the spread of coronavirus?

When it comes to face masks, the effect depends on quality and how they are worn. Even the best masks will fail if loose, leaving a large gap between the face and the mask, or covering only the mouth, not the nose.

As far as quality is concerned, some studies recommend three-layer masks made of different fabrics with different mechanical and electrostatic filtering properties for maximum efficiency. Therefore, the World Health Organization has stated that inner hydrophilic materials such as knitted cotton, intermediate polypropylene layers for good filtration, and outer hydrophobicity such as polyester or polyester-cotton blends to repel droplets and moisture. Material is recommended.

It should also be mentioned that despite the Ministry of Health’s warning, some people are using masks with exhalation valves. This may protect the wearer, but it can affect others. In fact, the above Physics of Fluids research paper also looked at masks with expiratory valves, “as a means of source control as large amounts of droplets (emitted by the wearer) pass through the mask. The effectiveness of the mask has been significantly reduced. Unfiltered valves. “

Properly wear a good quality mask without valves. For additional protection, you can wear a shield over it.