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They certainly don't help with PM2.5 Also let's not forget some people come from places where the AQ is like that, constantly for a big fraction of the year. Ever been to China or Mexico City?

Edit: Ok, if we're talking about KN95 then that's another story, I'm talking about the usual "face mask" which is little more than a fashion piece.

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> They certainly don't help with PM2.5

The requirement for a mask to be called KN95 is that it must filter out 95% of PM2.5 particles.

> AQ is like that, constantly for a big fraction of the year. Ever been to China or Mexico City?

Honestly, I'm not sure why those people don't wear a mask year round. I'd expect the rationale to be cultural, "no one else is doing it", rather than logical.

South Korea made their own non-industrial pollution mask standard, KF94, because they get so much pollution from China. Also, many of the older air purifier brands (Coway, Winix) are South Korean.

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