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Aerosols Can Travel 10 up to 10 Metres: Here's Why Double Masking Can Keep Covid at Bay


Last Updated: May 20, 2021, 17:23 IST

A man wearing a protective mask walks past a graffiti. (Reuters)

A man wearing a protective mask walks past a graffiti. (Reuters)

Wearing two tightly-fitted face masks can nearly double the effectiveness of filtering out SARS-CoV-2-sized particles, preventing them from reaching the wearer's nose and mouth and causing Covid-19.

Amid the catastrophic second Covid-19 wave ravaging the country, the central government on Thursday warned that smaller aerosol particles can be carried in the air for 10 metres, and emphasised on the need to wear a double layer mask or an N95 mask, which offers maximum protection.

“Ideally surgical mask should be used only once, but when pairing, you can use it up to 5 times by leaving it in a dry place for 7 days after one use (ideally give it some sun exposure),” said the office of the government’s principal scientific adviser K VijayRaghavan.

A study in April had found that wearing two tightly-fitted face masks can nearly double the effectiveness of filtering out SARS-CoV-2-sized particles, preventing them from reaching the wearer’s nose and mouth and causing COVID-19.

Speaking on the need for wearing double masks, AIIMS Director Dr Randeep Gulleria said ideally N-95 masks should be worn, but they may not be easily available. The next best option is double masking, with an inner layer of 3 ply surgical mask and a cloth mask over it. In case the first two options are not available, then two layers of cloth mask should do the needful, he said.

While N-95 masks have a filteration efficacy of 90%, surgical masks are 85%-90% protective and then the cloth masks, Gulleria explained. “Most important things is properly wearing a mask. You need to ensure, the air comes through the filtering mechanism of the mask otherwise you will get infected. Taking a deep breath and seeing the mask getting sucked in can tell you whether you’re wearing it properly or not.”

Why Double Masks?

A research, published in the journal JAMA Internal Medicine, has shown that the reason for the enhanced filtration is not so much adding layers of cloth, but eliminating any gaps or poor-fitting areas of a mask. “The medical procedure masks are designed to have very good filtration potential based on their material, but the way they fit our faces isn’t perfect,” said Emily Sickbert-Bennett, an associate professor at the University of North Carolina (UNC) in the US, and lead author of the study.

How Two Fitted Masks May Double Protection Against Covid

To test the fitted filtration efficiency (FFE) of a range of masks, the team filled a 10-foot by 10-foot stainless-steel exposure chamber with small salt particle aerosols. The researchers wore a combination of masks to test how effective they were at keeping particles out of their breathing space. Each individual mask or layered mask combination was fitted with a metal sample port attached to tubing in the exposure chamber that measured the concentration of particles entering the breathing space underneath the researcher’s mask. A second tube measured the ambient concentration of particles in the chamber. The researchers determined the FFE by measuring particle concentration in the breathing space underneath the mask compared to that in the chamber.

“We also had the researchers in the chamber undergo a series of range-of-motion activities to simulate the typical motions a person may do throughout their day — bending at the waist, talking, and looking left, right, up and down,” said Phillip Clapp from the UNC School of Medicine. According to their findings, the baseline FFE of a mask differs from person to person, due to each individual’s unique face and mask fit. Generally, a procedure mask without altering the fit, is about 40-60 per cent effective at keeping COVID-19-sized particles out, the researchers said. A cloth mask is about 40 per cent effective, they said.

Their latest findings on doubling of face masks shows that when a cloth mask is placed over a surgical mask, the FFE improved by about 20 per cent. The filtration efficiency improved even more with a snug-fitting, sleeve-type mask, such as a gaiter, according to the researchers. When layered over procedure masks, cloth masks improve fit by eliminating gaps and holding the procedure mask closer to the face, consistently covering the nose and mouth. When a procedure mask is worn over a cloth mask, FFE improved by 16 per cent.

Where to Wear the Masks:

– Masks are a must EVERY time you step out of your house.
– People visiting a public place including hospitals, banks, markets, parks, offices must wear face masks.
– Masks are a must inside a public transport.
– People must wear a mask inside a private vehicle too.
– Face masks should be avoided when running or exercising.

The Right Way to Wear Face Mask

– Touch your masks with clean hands. Wash your hands before putting on your mask.
– Do not put the mask around your neck or on your forehead. Secure it under your chin.
– Wear the mask over your nose and mouth. Try to fit it snugly against the sides of your face. Do not let leave your nose out
– Make sure you can breathe easily.
– Always hold the masks by ear loops or ties and not do not touch the face covering.
– Remove your mask when you get home.
– A cloth mask must be washed after EVERY use.
– A paper mask must be thrown away after each use.
– Make sure not to touch your eyes, nose, and mouth when removing the mask.
– Wash your hands immediately after removing it.

Discard Your Masks Carefully

The Mask etiquette not only includes how you wear the masks but also how you dispose them. Masks and gloves used by people to avoid the coronavirus and discarded carelessly has added to the list of trash left behind or washed up on beaches around the world. “PPE litter is a gross result of the pandemic, and 100% avoidable. Use PPE properly, then dispose of it properly in a trash can,” said Cindy Zipf, the executive director of New Jersey’s Clean Ocean Action environmental group

Discarded masks and gloves started showing up on beaches not long after the virus began circulating widely last year, and continued to appear as quarantine-weary people sought an escape at the beach. In the second half of 2020, more than 107,000 items of PPE were collected by volunteers around the world according to the Ocean Conservancy group a figure its members believe is a vast undercount of the year’s true totals. It reported last month that 94% of its cleanup events found discarded PPE, with masks accounting for 80% of the total.

The masks are made of materials that will not break down easily; by some estimates it could take 450 years for one to decompose in the environment. Conservationists have reported sea birds becoming entangled in the ear straps of face masks, and they worry that marine life could eat masks or gloves, mistaking it for food, and suffer serious or fatal consequences.

Masks Must Until Vaccines Fully Mitigate’ Covid Impact

Non-pharmaceutical interventions (NPIs) such as physical distancing should be stringently continued until vaccinations can fully mitigate the impact of the spread of SARS-CoV-2 and its known variants, says European Centre for Disease Control (ECDC) Director Andrea Ammon. A significant increase in COVID-19 related cases and deaths can be anticipated if NPIs are not strengthened and complied with, the German physician said as India added a record 2.17 lakh new infections on Friday, taking its total tally to 1,42,91,917 (1.42 crore/14.2 million).

“Effective implementation of the NPIs in response to the epidemiological situation remains essential for the continuing response to emerging and regularly circulating of SARS-CoV-2 and known variants. It must be continued until and unless vaccination has been shown to fully mitigate the impact of the pandemic on the population and healthcare services,” Ammon told .

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first published:April 27, 2021, 09:52 IST
last updated:May 20, 2021, 17:23 IST