|
Example of wearing a mask that was not sealed well.
Perhaps this is not important anymore since lots of people no longer wear mask, but I think we still got a long way to go. During the early days of the pandemic (around March/April 2020) I did a number of controlled experiments to show the effect of quality of filtering material v.s air gaps in a mask. Yesterday I accidentally created a real life example of how a not well sealed mask would allow virus to easily get in. As you look at the images and read the text, keep in mind that air or liquid moves along the path of least resistance.
For about half an hour I was cleaning the fireplace and chimney while wearing a KN95 mask in the attached photos. I was totally aghast in looking at the mask after the job. Notice the two black spots INSIDE the mask where my nostrils were. Note there was no corresponding black spot on the OUTSIDE of the mask. Those black spots were soot particles that I breathed out. If the mask did a good job, one would expect the exact opposite. i.e black spots on the OUTSIDE only. What happen was soot particles slid/slipped on the outside of the mask due to a combination of the mask’s CONVEX outside surface, filtering layers, and inhale suction. These particles and those right next to gaps that were around the nose (imperfect seal even with pinched nose wire), cheeks, and chin were sucked in on each of my in-breath. With exhale pressure, some (or most) of the soot particles in my lung, nose, and inside the mask were forced out and trapped in part due to the mask’s CONCAVE inside shape, resulting in two black spots inside the mask.
Virion are much smaller than soot particles, though they are in respiratory droplets. Some droplets are smaller than soot particles. So no matter the quality of a mask’s filtration layers, if it’s not sealed around your face, virus will get in.
Nguyen
|