Even if there’s six feet of space between you and another person, a recent study published in the British Medical Journal (BMJ) notes that the recommended two yards is not sufficient in every scenario. Other factors such as length of exposure time, ventilation of the space you’re in, if people are yelling or singing, and the size of the crowd you’re with can make the advice to merely “keep your distance” woefully inadequate. In situations like that, a face covering is a must, no matter how much space you have.ae0fcc31ae342fd3a1346ebb1f342fcb “I’ve seen a lot of guidelines that say wear a mask if you can’t maintain distance, but I think that we need to be wearing a mask at all times when we’re indoors with other people outside of our own homes,” Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, told NBC News. Mounting research has shown that not only are face masks effective in stopping the spread of COVID overall, but they may also offer the greatest protection when you’re indoors. In fact, another study published in The BMJ in May found that households in which everyone wore a mask indoors before anyone had COVID symptoms saw the risk of transmission drop by 79 percent. “The more people that were wearing a mask, the more protective it was,” Raina MacIntyre, study author and head of the biosecurity program at the Kirby Institute at the University of New South Wales in Australia, told NPR. RELATED: For more up-to-date information, sign up for our daily newsletter. Even those making a quick trip inside should be covering their faces. “Even if you’re inside for just a minute or two, you’re still protecting other customers and the workers,” Natascha Tuznik, assistant clinical professor of infectious diseases at UC Davis Health, said in June. “You’re helping them feel safe. And since your time in there is brief, that’s even easier.” Of course, the CDC’s official guidelines still state that it’s important to remember that while mask-wearing is incredibly effective, it’s best to practice all of the guidelines in conjunction with each other, not only when social distancing isn’t possible. And for more on the smartest way to cover up, check out These Are the Best and Worst Face Masks, Ranked by Science.