Coronavirus genre (alpha, beta, gamma, and delta) (yes there are types just like there are many strains of influenza – one reason that the same flu vaccine doesn’t work each year) – has an average size of 27 – 32/34 kb (kilo bases). The one we are most concerned with is the beta version.
https://www.scireslit.com/Virology/IJVID-ID13.pdf
So what is the size and why does size matter?
Coronovirus COVID19 specific size: 0.09 to 0.125 µ
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1563832/
What does the micron or whatever size mean?
Width of hair = (note this is average, not typical) = 75 µ
Why does size matter?
It determines whether the virus can pass through filters or not.
Masks/Filters
N95 Masks: N95 designation the 95 means it will block out 95 % of the particulate matter and typically filter out contaminants as small as 0.3 µ
What does that mean? It means given current information on the size of the coronavirus (beta version) which is at 0.09 smallest to 0.125 µ, it is still too small to effectively stop the coronavirus if it were separate as is. But usually transmission from one person to another is through breath, cough, saliva etc. This means there will be a coating of water, mucus, (or other junk) that would be enveloping the virus.
So it would be reasonable to assume that given a coating of ‘something larger’ will make the overall size of the virus large enough to be stopped enough with an N95. Currently this is used by medical staff for treating patients with coronavirus.
If you have some masks, good for you. Don’t waste your filters wearing it when you are not sick. If you breathe through them and moisture builds up, that is a breeding ground for bacteria and other viruses and compromises the filtering effectivity/efficacy of the masks.
Currently in the USA, there are limited masks/filters available (specially N95) and are at an exorbitant price due to shortages. So, don’t waste the masks by wearing it to for daily routine. Leave it for those who need it more.