Pulmonologist Dr Sundeep Salvi, who is also Director of Pulmocare Research and Education Foundation, answers questions on masks.

Man seen wearing a maskImage for representation
Coronavirus Coronavirus Monday, May 25, 2020 - 17:21

At a time when Indian cities are slowly opening up after a complete lockdown, whether you want to step into your neighbourhood department store or into a cab, you won’t be allowed in most places unless you wear a mask.

With masks set to become part of the new normal in a world still dealing with COVID-19, there are many questions. How much protection does a mask provide? Can you use just about any face cover or mask to guard against COVID-19? How long will we have to use masks?

On Monday, Dr Sundeep Salvi, Director of Pulmocare Research and Education Foundation (PURE), based in Pune, answered these questions and more. He was addressing a webinar called ‘Chronic Respiratory Diseases in the context of COVID-19’ organised by REACH, an organisation that works towards a tuberculosis-free India.

When you should wear a mask

One of the ways the virus enters the human body is when an infected person sneezes, coughs or talks, releasing droplets that are inhaled by another person in the vicinity. Apart from coughing and sneezing, talking itself can cause one to expel droplets that can travel up to 24 centimetres, says Dr Salvi. According to other research, droplets from a cough or sneeze can help the SARS-CoV-2 virus travel up to eight metres.

Dr Salvi advises universal use of masks in community settings. “There are two reasons behind this – one is to prevent transmission if one is infected, and the other is to protect oneself from inhaling the virus transmitted from an infected person.”

Initially, the World Health Organisation (WHO) had advised that only infected people and those working in proximity with infected persons or as their caregivers need to wear masks. An updated advisory from the WHO dated April 6, 2020 does not vary too much from this. “There is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses, including COVID-19,” WHO says. While the Centre for Disease Control and Prevention also said something similar earlier, it changed its stance later, advising Americans to wear “cloth face coverings in public settings where other social distancing measures are difficult to maintain” especially in areas where community transmission is prevalent.

These conflicting advisories worldwide is because emerging evidence has shown that SARS-CoV-2 can be transmitted by pre-symptomatic or asymptomatic individuals too, who could believe they are healthy as they do not show symptoms. To prevent this, many countries like Singapore and Hong Kong advised wearing masks in public places as early as January this year.

What type of masks should one use?

There are various types of masks available, and while surgical masks and N95 masks have been frontrunners, different masks are suitable for different settings, Dr Salvi explains. It is also noteworthy that while there are masks that provide more protection than N95 masks (that filter out 95% particles that are less than 300 nanometres in size) like N99 and N100 masks, it does not necessarily mean they are more suitable for use.

“This is because though N99 and N100 masks filter out more particles, they also make it hard for the wearer to breathe. This is why N95 masks are deemed adequate, when coupled with other measures like good hand hygiene and physical distancing,” Dr Salvi explains. “It’s the same reason we cannot use a mask made of plastic. It will provide 100% protection, but you won’t be able to breathe,” he adds.

Further, there are different kinds of N95 masks as well – a non-foldable one, a non-foldable one with a valve, and a foldable one. “In the context of COVID-19, a non-foldable one without a valve should be used because when you are breathing or speaking through the valve, you expel many more droplets that you would through one that does not have a valve. While it is ok for doctors and nurses to use this, a valved N95 mask shouldn’t be used in a community setting,” he says.

It is also important to use authentic N95 masks, as fake N95 masks have been confiscated in various places like China as well as in Bengaluru.

What is the right way to wear a mask?

It’s not enough to just wear a mask – it has to be worn the right way – tightly, with minimal gaps, to actually offer protection, Dr Salvi says. Masks have a pin around the bridge of the nose which should be adjusted to eliminate the gap, he adds. For instance, an N95 mask worn without a gap can provide 85% +/- 15% protection from particles less than 300 nanometres in size, which reduces to 34% +/- 15% if worn with a gap.

But what does this mean for people who are wearing cloth ties or scarves around their face. Dr Salvi says, “There hasn’t been enough research into this; but while it may not completely serve the purpose of protection from the virus, it would still work for prevention of transmission from the wearer.”

He adds that it is equally important to remove and dispose of a mask the right way. “One should not touch the front of the mask at all, because it increases the risk of infection. Take the mask off from behind the earlobes only and dispose it or wash it, if it is reusable.”

Home-made masks – what materials work best?

Over time, the Indian government has encouraged people to use reusable cloth masks which people can make at home as well.

But not all materials provide the same protection. A study done in April compared the protection provided by masks made from different materials such as cotton, silk, chiffon, and blends of these. It was found that cotton and chiffon blend provided protection up to 97% from particles that are less than 300 nanometres in size, like the SARS-CoV-2 – almost at par with a properly worn N95 mask. Further, a cotton quilt material provided 96% protection, while two layers of a cotton material with 600 threads per inch would provide 82% protection.


Graphic courtesy Dr Salvi's presentation

What’s the right way to wash a reusable mask?

Dr Salvi says if he had to choose between an alcohol-based disinfectant and soap to wash a reusable mask, he would choose the latter. “You don’t even need to put a disinfectant in the water if you use a normal detergent. Just soak the mask in water with detergent for some time, lightly rinse it to avoid expanding the thread density, and set it to dry.”

This is because the SARS-CoV-2 is very vulnerable to soap, because soap can easily break down the fatty lipid molecules that surround the virus.

Will wearing a mask alone protect me from coronavirus?

It is easy to get lulled into a false sense of security if you believe that just wearing a mask will protect you from the novel coronavirus. However, experts, including Dr Salvi, repeatedly point out that this has to be accompanied by hand hygiene and physical distancing to provide maximum protection. One cannot replace the other.

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