Here we are again. Shaking in our boots because of COVID-19.

Sure, this new variant (omicron) seems far less lethal, but it’s more prone to infect us. (That’s what happens when the SARS-CoV-2 virus adopts characteristics of the common cold virus. That’s what can happen when an uninoculated subject is invaded by the SARS-CoV-2 virus while suffering from – or about to – the common cold.)

And, then, there’s the mask issue. And, social distancing. And, some false initial assumptions.

We thought the the virus was going to be suspended in droplets. As opposed to be in a mist. So, that’s where the 6 foot distance concept arose. Because a slew of droplets would tend to have settled to the ground over a distance of less than 2 meters. But, as was shown in experiments by Drs. Ali Khosronejad and Fotis Slotriopoulos (Stony Brook), Seokkoo Kang (Hanyang University, Korea), Fabian Wermelinger (ETH, Zurich), and Petros Koumoutsakos (Harvard), the distance is far greater for the COVID-19 virus. (A computational study of expiratory particle transport and vortex dynamics during breathing with and without face masks, )

Normal breathing without a face mask affords the ability for the virus to travel about 2.5 meter from the subject. Facial masks attenuate the forward motion, and they also direct the flow downward- so much so that the travel distance is around 3/4 of a meter (considerably less than the 6 foot social distance mark). Note that these results are for normal breathing- not coughing, which involves greater kinetic energies.

Then, we come to the concept of which masks should we don. Do we use N95, KN95 (which are subject to Chinese regulations), surgical masks (aka disposable medical masks), or multi-layer cloth masks? (Don’t even consider single layer cloth masks.)

First, if everyone in the room is wearing a mask- regardless of the mask type, then the risk of viral transmission is extremely low. (No one can ever say non-existent.)

Then, we get to the cloth masks. Single layer cloth masks might be (yes, might- let’s say around 30%) effective at attenuating the spraying of viral particles, but not effective at blocking inhalation of the virus. Multiple layers are reasonably effective at both.

There is a simple test as to how effective the masks might be- if you happen to wear glasses and they get fogged when you are wearing a mask- either the mask is not placed properly over the nose or it is an ineffective barrier. The advantage of a multi-layer cloth mask (a properly constructed multi-layer cloth mask can approach 90% effectiveness against the virus) is that it is highly comfortable- so it is more likely to be worn. These masks need to be cleaned and sanitized frequently. (See below for sanitizing routines.)

If you were to pour water into any mask and that water freely flows out, then that mask is not one you should be using.

The surgical masks (which are multi-layered, of course) are more effective than cloth masks. As long as the wearer clearly makes sure that the nose guard is firmly secured about ones’ nose. However, once this mask gets dirty or gets wet during the day, it’s time to discard it. And, these sort of masks are to be discarded after each day’s use.

Many folks are using cloth masks atop surgical masks. That concept means they are achieving an effectiveness akin to that of the N95’s.  This also makes it tougher for the surgical mask to get wet or dirty, so it can survive a whole day’s usage.

Then, there’s the N95 masks. These are highly effective, as long as they are properly worn. Much of that relies on the straps that go over one’s head and neck, applying more pressure against the face. (That also means the masks are clearly secured against the nose.) The KN95’s (again, under Chinese regulations, which only rely on ear straps, so they are not as tightly against the face) are less effective than the N95’s, but are a good second alternative.

These latter two masks (ok, realistically, just the N95 masks) are the masks of choice if we are caring for someone who has tested positive for COVID-19.  The risk in this case is clear and evident; we need the best protection, since we will be in close contact with someone who can clearly infect us.

Then, we get to the special case of kids. They are easily infected if a nearby infected child (not wearing a mask) is breathing or talking and facing the child’s face- even with a mask. The issue is that kids are voluble- laughing, talking, screaming, playing… (If both are wearing masks, the infectivity possiblity is dramatically reduced.) College kids are far more subdued- taking notes and sitting quietly, so there is much less of a risk.

Which brings up the issue of folks attending sporting events or rock concerts. Where they are just as likely as little kids to scream and yell, even to jump up and down (which can cause the mask to be less firmly placed against the face). Yep, that’s exactly why those are “spreader events”. Folks take their masks off to drink and eat (and a slew of folks never even wear a mask), they scream and yell, creating viral vectors throughout the venue. In other words, right now, it’s not a smart move to attend such an event.  (My son found that out- he attended the devastating loss of Michigan to Georgia at the Orange Bowl.  And, then tested positive for COVID-19.)

Mask Disinfection:

Place the mask in a vegetable steamer or a noodle pot, with water in the lower layer. Boil the water for about four or five minutes. The rising steam will disinfect the mask. (This method is NOT acceptable for surgical masks or any masks that are primarily paper.)

 

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