Do Masks Block The Virus?
Do masks block the SARS-CoV-2 virus?
Do masks block the SARS-CoV-2 virus?
Here is how the SARS-CoV-2 virus looks when it is frozen, thinned, and then
imaged using an electron microscope. The bar on the
bottom right corner is 0.03 micron long (one micron is one-millionth of a
meter). As you can see, the SARS-CoV-2 virus, including the spike proteins
surrounding it, is about 0.1 micron in diameter.
On its own, a 0.1 micron-wide SARS-CoV-2 virus can pass through an N95 mask, whose pores are on average about 30 microns wide (source). Fortunately, a SARS-CoV-2 virus is never in the air on its own. It is always attached to a tiny droplet of saliva. Most of the droplets expelled by sneezing or coughing tend to be 40 to 1,000 microns in diameter, which is wider than the average pore size in an N95 mask, which is estimated to block 95% of the droplets in the air that carry the SARS-CoV-2 virus.
Why doesn't it block 100% them?
While the average diameter of the pores in an N95 mask is 30 microns, the range is from 10 to 60 microns, and while most of the droplets expelled by sneezing or coughing are 40 microns wide or wider, there are also smaller droplets; the smallest droplet capable of carrying a SARS-CoV-2 virus is estimated to be about 5 microns wide (source).
What about cloth or surgical masks?
They have larger pores and also lack the N95 mask's other microscopic features that enhance the level of protection it affords.