My January 30 post “A Filter By Any Other Name” was a popular one. Shortly after posting it, Dr. Fauci floated a now popular sentiment that if one mask is good, two must be better. Soon the CDC released unspecified testing that two masks are indeed better than one.
Here’s a quick video showing the masks available and what they are are good for. My expertise? 30 years in the Personal Protection Equipment business, specifically respiratory protection at 3M and Honeywell.