The KF94 is the best mask to protect against Covid-19 on the market in South Korea. How does it stand the test of a hike? Is it breathable? And how long does it last? The KF moniker refers to masks manufactured in South Korea. KN is China (KN-95). N is United States (N95). The numerical value is the percentage of particles that will be filtered if worn PERFECTLY. That means you absolutely seal all edges. One crude test to see if your mask is fitted properly is that you shouldn’t be able to smell anything around you like car exhaust or cooking aromas.
I’ve heard that the masks are designed to officially withstand about 3 hours of use. They start to break down because they’re composed of paper material that’s meant to be disposable. But of course with mask shortages in some areas we’re really extending the limits. The main purpose is not necessarily blocking what’s coming in perfectly. It’s blocking what’s coming out. The fewer virus particles we release into the common air supply, the better protected we all are.
When doing exercise, most people opt to wear masks with less protection (dental masks, KF-AD or KF-80) in order to increase breathability. Cotton masks are better than nothing, but make no mistake, you are spewing many more particles into the air.