The coronavirus is far from being done with us. Yes, it almost 2 years since COVID reared its head, but the pandemic isn't over yet!

Let us first get away from this perception that the Omicron variant is “mild” and hey, it’s just like a bad cold.

Unfortunately, that still includes a major part of the world. Further, “mild” is a misnomer. Even Dr VK Paul, Niti Aayog Member (Health) cautioned that Omicron isn’t a cold.

And in medical language, “mild” just means you may not need supplemental oxygen, get admitted to an ICU, or be put on a ventilator.

For those who are elderly, unvaccinated, and have other diseases, even the Omicron variant can lead to severe complications and even death.

More important, since many health care workers are themselves COVID +ve and have to quarantine for a week, this has a cascading effect on all other kinds of medical care for those who may need it. So, it’s time to up our guard and be extra careful!

While we may or may not know a lot about the SARS-COV-2 virus and the new variants, the one thing which is well proven and known for sure, is that masks and vaccines work.

Looking around the streets and public spaces, in offices, or in buses and trains most people just do not wear masks correctly, and take every opportunity to remove them off!

The mask is sometimes pulled below the nose, and quite often just a perfunctory chin-ornament.

Proper fit is as important, if not more, than the filtration efficiency of a mask. We cannot emphasize enough that a properly-fitting mask should cover one’s nose, mouth and chin at all times, and leave no gaps over the nose, on the sides of the face, or around the chin.

The mask should be tight enough to stay in place even when you talk or move around (Sure, you can talk with others or even on the phone without removing your mask!).

Now what mask does one use, and what is the easiest way to make sure that the mask can be re-used safely?

There are cloth masks (which must have at least 3 layers), the typical blue pleated surgical masks, and the N95 or KN95 masks, which are the most efficient in filtering small particles.

(N95 was originally a US specification, with KN95 being the Chinese one, Korea has KF94, and the equivalent in Europe is FFP2. India has IS 9473:2002 Class FFP2, but N95 is the more common term in use).

Remember, N95 masks with exhalation valves are a strict no-no.

They might make it easier to breathe, but for an infected person, they offer no protection to people around.

Cloth masks of course can easily be washed every day and dried and reused. However, they rely on mechanically filtering (like a sieve) the inhaled air passing through the cloth fibres, and are not as efficient as N95 masks filtering out the very small particles.

On the other hand, N95 masks achieve their 95% filtration efficiency due to a layer of very fine meltblown polymer fibres, that are electrostatically charged, and can attract these tiny particles.

We now know that COVID is an airborne disease where the viral particles can be carried by very small droplets that remain in the air for a long time. Hence masks with better filtration efficiency for small particles, if worn properly, would naturally offer better protection.

(Watch this video to know how to double mask up properly)

This provides much better protection than either a cloth or surgical mask by itself.

But, if one can afford N95 masks (and they are now widely available and not that expensive anymore) it is quite easy to re-use them.

Washing an N95 mask, or using hand sanitizer solution to decontaminate it is not recommended, as it removes the charge that is critical to the filtration, and lowers the efficiency.

While it won’t go down to zero, the filtration efficiency for fine particles might still be about 70% or so, but it is still will not be at N95 level performance anymore!

(Most of the “UV boxes” sold for surface decontamination do not have enough energy to penetrate through the mask layers in a short time and guarantee a safe reuse.)

However, it is now known that the SARS-COV2 virus does not survive on any surface for more than about 96 hours.

Hence, if there is a 5 day gap between using the same mask again, it is safe to be re-used. If one has a set of 5 masks (label them!) and uses Mask 1 on Day1 … Mask 5 on day 5, the 1^st mask can be safely reused on Day 6 and so on.

Alternately, you can have one mask for each day of the week – a Monday mask, a Tuesday mask, and so on. Just keep the mask in an open airy place, maybe in a paper bag.

Of course, given the overall pollution and dust load in our environment, one can’t do this forever, since the dust particles will slowly clog up the pores of the mask. But a set of masks can easily be cycled 5-10 times before they need to be replaced.

Given a choice, a mask that can be tied tightly around the head, than just being fixed by an elastic band around the ears, provides a much better fit and protection.

Also, it saves the ear lobes from the tenderness that is inevitable when wearing a mask for hours every day.

By using masks correctly, and getting vaccinated, we can significantly reduce the probability of us coming down with the virus or having severe disease.

It is time for each one of us to choose better quality masks if possible, but most importantly, wear our masks properly!

(Arnab Bhattacharya is Centre Director, Homi Bhabha Centre for Science Education, Tata Institute of Fundamental Research, Mumbai.

Dr CS Pramesh, Director, Tata Memorial Hospital, Mumbai)