South Korea's KF94 mask does a good job concealing the Mona Lisa's smile — but how effective is it at preventing coronavirus spread?

South Korea's KF94 mask does a good job concealing the Mona Lisa's smile — but how effective is it at preventing coronavirus spread.

As Stephen Morse, an epidemiology professor at Columbia University, puts it, a KF94 is essentially the South Korean equivalent of the N95.

Sonali Advani, an assistant professor of medicine at Duke University, explains that KF stands for "Korean filter." And 94 refers to its filtration efficiency (basically, just how good the mask is at filtering out particles we don't like), which is 94%.

But Advani doesn't think the KF94 is a game changer for how we should all approach mask strategy?

"When it comes to use in day-to-day activities, overall surgical masks and three-layered cloth masks perform pretty well," Advani says.

In other words, she says, there's no need to go out and buy up medical-grade KF94s — especially, she says, since some wearers have said the South Korean mask is less comfortable or harder to breathe out of than the alternatives.

"While these masks [such as the KF94] may be better for use in a hospital [because they're designed for medical settings], in the real world, it may be the case that they are hard to wear through the course of the whole day.

If you do end up choosing to invest in a KF94 mask, Morse warns to be wary of counterfeits

"Not all KF94 masks are made in Korea — many are manufactured in China — [but] KF94s manufactured in Korea may be less prone to counterfeiting," he says