Masking and Microns

Graphic only from https://www.straitstimes.com/lifestyle/what-makes-an-effective-diy-mask

Coronavirus: 0.1μm (the speck on the far left)

Pore size of N95: 0.1 -0.3 μm (0.1-0.3 microns)

Pore size of standard surgical mask: 0.3-10 μm

I like this graphic.  For a mask to work, it needs to filter out particles.  This requires that the pore size of the mask be smaller than the particles it is filtering.  It also requires a tight fit:  no leaks.  If there is a bit of a charge on the mask that repels particles, as intended with new N95 masks, all the better.

As you can see from the picture, aerosolized coronaviruses can easily squeeze through the pores in a surgical mask, which may have a diameter 100 times larger than a single virus. But the bigger issue is the leaks--the masks don't fit snugly.  It is almost impossible to both get a tight fit and be comfortable in a properly worn mask for more than a few minutes.

So instead we are wearing leaky masks that stop spit but don't stop aerosolized viruses.  What was told to the public early in the pandemic (and buried later) is that all the mask really does is stop you spitting at other people.  It does not help the wearer much.  Taking it on and off is a big contamination risk. 

Remember the anthrax letters.  Spores escaped through several layers of paper because the pores in the paper and envelopes were more than ten times larger than the diameter of the spores. The pores in the paper were as big as that boulder on the right, the same size as the pores in surgical masks.  And coronaviruses are only one tenth as large as anthrax spores.  Uh oh.

Wearing a mask outdoors is a joke.  Wearing a mask indoors--well, if you want to be serious about masking, get yourself some N95 masks, get fit-tested, and use a new one each time you put it on.  That is a good strategy.  The rest is mostly wishful thinking.

Update April 30:  India issues comprehensive masking instructions for home caregivers with Covid patients. This is part of a longer guidance on managing Covid, which does include advice on ivermectin. When even India does a better job of informing its citizens about the proper home care of Covid, what does that tell you? BTW, according to our world in data, currently India and the US have the same official Covid death rate per million--and the US' rate is the lowest it has been in six months.

Instructions for caregivers 

i. Mask: 

The caregiver should wear a triple layer medical mask. 

• N95 mask may be considered when in the same room with the ill person. 
• Front portion of the mask should not be touched or handled during use. 
• If the mask gets wet or dirty with secretions, it must be changed immediately. 
• Discard the mask after use and perform hand hygiene after disposal of the mask. 
• He/she should avoid touching own face, nose or mouth.

There is additional guidance regarding the use of ivermectin, budesonide, oral steroids and other medications.