RELATED: This One Type of Mask Won’t Protect You From the Delta Variant, Expert Says. Cloth masks have been widely used by people around the world since the beginning of the pandemic, becoming particularly popular when medical masks were in short supply for frontline workers. But this type of face covering may no longer cut it in certain situations. According to Travel + Leisure, many major international airlines now ban masks made from cloth fabric, including Finnair, Air France, Lufthansa, Swissair, Croatia Airlines, and LATAM Airlines. These airlines are only allowing other, more effective masks, such as N95 masks, KN95 masks, surgical masks, and respirators without exhaust valves.ae0fcc31ae342fd3a1346ebb1f342fcb RELATED: If You’re Using This Mask for Protection, Throw It Out Now, FDA Warns. Finnair is the most recent airline to have banned cloth masks on Aug. 13, stating that the face covering is not protective enough. “The safety of our customers and employees is our first priority. Fabric masks are slightly less efficient at protecting people from infection than surgical masks,” Finnair said in a statement. A recent study being peer reviewed for publication in the journal Science and pre-printed early on Aug. 13 backs this up. Researchers for this study analyzed more than 340,000 adults from 600 villages in rural Bangladesh, finding that cloth masks did not perform in the same way as surgical masks. The study authors said that while they found “clear evidence” that surgical masks are effective at reducing symptomatic COVID, they could not say the same for cloth masks. According to the study, surgical masks had a filtration efficiency of 95 percent, while cloth coverings were only 37 percent effective. “While cloth masks clearly reduce symptoms, we cannot reject that they have zero or only a small impact on symptomatic COVID infections,” the authors wrote. “Surgical masks have higher filtration efficiency, are cheaper, are consistently worn, and are better supported by our evidence as tools to reduce COVID-19.” It’s not yet clear whether any major U.S.-based airlines will follow suit in banning cloth masks, but it might be worth preparing for, according to Fast Company. In fact, there are various types of face coverings already not allowed by some of these airlines. Although Delta Air Lines states that “cloth masks with tightly woven fabric are still permitted,” it currently prohibits passengers from wearing bandanas, scarves, masks with exhaust valves, and any mask with slits, punctures, or holes. United Airlines says that bandanas are not permitted, and notes that a “face shield alone does not count as a face covering.” Both Southwest and American Airlines have also banned balaclavas, bandanas, and scarves. RELATED: For more up-to-date information, sign up for our daily newsletter. U.S. airlines could implement a ban on cloth masks some time this year, as the federal mask mandate for airlines has been extended. This order was first implemented in January and set to expire on May 11 before being extended to Sept. 13. But on Aug. 20, the Transportation Security Administration (TSA) announced that it would be extending the federal face mask requirement once again, this time through Jan. 18 of next year. “The purpose of TSA’s mask directive is to minimize the spread of COVID-19 on public transportation,” a spokesperson for the administration told Business Insider. RELATED: This Type of Mask Won’t Protect You From COVID Right Now, New Study Says.