The difference between N95 and KF94 masks are minor for the factors that most users care about. KF94 is the “Korea filter” standard similar to the US N95 mask rating.
Difference Between N95 and KF94 Masks: Charted Out
They look similar, and they filter a nearly identical percentage of particles—95% versus 94%. This chart from 3M explains the differences between the N95 and “first class” Korean masks. The columns highlight these two types of mask.
On the metric that most people care about (filtration effectiveness), they’re nearly identical. In most circumstances, mask users will not care about a 1% difference in filtration.
KF94 Standards Borrow More From Europe Than US
However, of the differences between the standards, the Korean standards are more similar to the EU standards than the US standards. For example, US certification agencies test filtering performance using salt particles, whereas European and Korean standards test against salt and paraffin oil.
Similarly, the US tests filtration at a flow rate of 85 liters per minute, whereas the EU and Korea test against a flow rate of 95 liters per minute. However, these differences are minor.
Other Differences Between Mask Ratings
Besides the 1% difference in filtration, there are some small differences on other factors.
- For example, the standards require N95 masks to be somewhat easier to breathe out of (“exhalation resistance”).
- Korean masks are required to test for “CO2 clearance,” which prevents CO2 from building up inside the mask. In contrast, N95 masks don’t have this requirement.
- To get the mask label certified, Korea requires human fit-tests, like the one I’m doing below. The US N95 certification does not require a fit test.
However, that doesn’t mean people shouldn’t do fit tests with N95 masks. The US agency that regulates workplace safety (OSHA) requires workers in certain industries to get fit-tested once a year. It’s just that fit tests aren’t required for the manufacturer to get the N95 label.
Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of Smart Air, a social enterprise to help people across the world breathe clean air without shelling out thousands of dollars for expensive purifiers.