I came across a Washington Post article in early October about finding the best (safest) face masks and followed up, checking various resources in the article.

One stood out particularly -- his name is Aaron Collins and he is a mechanical engineer who began testing various masks available to the public in 2020. He videoed his test sessions and then posted them on YouTube (mask nerd youtube). He also produced a spreadsheet which contains all his testing data on the face masks he has tested and where to buy them.

While some of you may prefer to wear N95s, especially for those of you who experience SOB, you might want to take a look at Aaron's videos (I'd start with his "top picks") and the spreadsheet. Those with the lowest number in the column "time to max breath" column would be the most breathable. However, there are lots of other things to consider -- the better the fit, the better the mask will protect one so the dimensions of the mask matters.

Aaron generally prefers the KF94s which are made in South Korea. The South Korean Ministry of Health sets certification and testing standards and South Korean manufacturers who can't meet those standards are not allowed to use the KF94 designation on their products. I personally wear a BOTN medium KF94 but keep in mind that I am 5'3", weigh under 115# and have a small face.

Also, if you are using fabric masks, watch his videos which discuss those.