Masks are crucial to fight the novel coronavirus, COVID-19. But there are many different types of masks available in the market like N95 masks, bandanna style, surgical masks, cotton masks, layered masks, stitched masks etc. Which masks are truly effective and keep us healthy? Manhar Dhanak, Professor and Chair, Department of Ocean and Mechanical Engineering, Florida Atlantic University says fluid mechanics is a study of how air flows, which is now an essential part of understanding how COVID-19 virus moves. According to their study, actions like coughing, sneezing, breathing, talking, laughing, singing emit different size droplets. The larger droplets fall to the ground quickly but smaller droplets, some smaller than our hair, can travel far and spread the virus. Without a mask, droplets sometimes travel upto 12 feet far from the source. Bandanna type masks allow for propulsion of droplets upto 4 kms. Cotton masks, though, help cut the propulsion of droplets to literally 2 inches, making them the best ones to use. Watch BOOM's Govindraj Ethiraj interview Manhar Dhanak on which masks are the best to use and why we should use masks without fail to combat COVID-19.