Cloth masks have become a staple of our pandemic lives. In the earliest days of COVID-19, we followed online tutorials to sew masks from old T-shirts. Soon, companies of all kinds—from Old Navy to designer Christian Siriano—flooded the market with masks, so we could keep a stash handy whenever we stepped out the door. But the era of the cloth mask may be coming to an end.

As COVID-19 continues to surge, accelerated by the delta variant, several European governments and companies are banning cloth masks, arguing that they are not as effective as medical masks in the midst of the current outbreak. Instead, they are mandating medical-grade masks. It’s unclear yet whether American companies will follow suit, but it could be worth preparing for that eventuality by understanding the difference between cloth and medical masks, and figuring out where to buy medical masks.

Many airlines now ban fabric masks on flights. Last week, Finnair was the latest to adopt this policy, joining Air France, Lufthansa, Swissair, Croatia Airlines, and LATAM Airlines in announcing that passengers would not be allowed to wear cloth masks on flights. The reason? “Fabric masks are slightly less efficient at protecting people from infection than surgical masks,” according to Finnair’s statement. Now, all of these airlines are only allowing N95 masks, surgical masks, and respirators that do not have exhaust valves.

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