Face masks don't make you invincible. Support Vox by joining the Video Lab at http://vox.com/join or making a one-time contribution: http://vox.com/contribute The fight against coronavirus is global. But the guidelines on whether you should wear a face mask as part of that fight are often completely different from place to place. That means that, for a lot of people, whether you wear a face mask when you leave the house is basically up to you. Here’s where almost every expert agrees: If you have Covid-19, and you leave the house, you should wear a mask. Masks help keep sick people from spreading their germs. Most of the uncertainty around mask use is related to a totally separate question: Whether masks can protect healthy people from getting Covid-19. The truth is that no mask can actually guarantee that you won’t get sick; experts say one of the most dangerous assumptions about face masks is that they basically make you invincible. Masks have to be used correctly to offer any protection at all, and they’re most effective if used alongside other preventative measures like hand-washing and social distancing. But experts also say that the question of whether healthy people should wear masks is a lot easier to answer when you consider one of Covid-19’s most dangerous characteristics: Because of the disease’s long incubation period, and the high occurrence of infected people who never feel symptoms at all, it’s almost impossible to be completely sure that you don’t already have it. And that means the safest course of action is ultimately for everyone to behave like a sick person; in other words, to wear a mask. More of Vox.com's coverage of face masks: https://www.vox.com/2020/3/31/21198132/coronavirus-covid-face-masks-n95-respirator-ppe-shortage An in-depth explainer on viral respiratory particle behavior and covid-19 transmission: https://medium.com/@Cancerwarrior/covid-19-why-we-should-all-wear-masks-there-is-new-scientific-rationale-280e08ceee71 The US Center for Disease Control's current guidance on face masks: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fcoronavirus%2F2019-ncov%2Fprepare%2Ftransmission.html An MIT disease transmission researcher's study on respiratory droplets and aerosols: https://jamanetwork.com/journals/jama/fullarticle/2763852 Ed Yong's great explainer on the confusion around face masks: https://www.theatlantic.com/health/archive/2020/04/coronavirus-pandemic-airborne-go-outside-masks/609235/ For the full Schlieren mirror video from Bauhaus University, Weimar: https://vimeo.com/399120258 The World Health Organization's updated recommendations on face mask use: https://www.who.int/publications-detail/advice-on-the-use-of-masks-in-the-community-during-home-care-and-in-healthcare-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak Our source for pre-symptomatic and asymptomatic cases: https://www.jhsph.edu/news/news-releases/2020/new-study-on-COVID-19-estimates-5-days-for-incubation-period.html The headline on this piece has been updated. Previous headline: Why you should wear a face mask to fight coronavirus Vox.com is a news website that helps you cut through the noise and understand what's really driving the events in the headlines. Check out http://www.vox.com/. Subscribe to our channel! http://goo.gl/0bsAjO Watch our full video catalog: http://goo.gl/IZONyE Follow Vox on Facebook: http://goo.gl/U2g06o Or Twitter: http://goo.gl/XFrZ5H