Coronavirus, here are the masks that best contain a cough

Any type of mask, even fabric ones, is effective in limiting the spread of a cough and therefore possibly coronavirus

(photo: Getty Images) Any mask is better than no mask to limit the spread of the new coronavirus. This is confirmed by a research, published in the journal Physics of Fluids, conducted by the experts of the Indian Space Research Organization and the Sri Jayadeva Institute of Cardiovascular Sciences and Research who through a series of experiments have visualized how the dynamics of a free and with different types of mask. Spoiler: N95 masks are the most effective.

The researchers used a fluid dynamics technique called schlieren imaging that visualizes changes in air temperature and density. Since the one expelled with a cough is hotter than the surrounding medium, the experts were able to record the flow trend (speed and diffusion) of the coughs emitted by 5 volunteers in different conditions of covering the mouth.

(image: Simha and Rao, Physics of Fluids, 2020) What emerged is that a free, open-mouthed cough travels up to 3 meters away. However, if we apply a simple disposable mask, the distance is reduced to 0.5 meters, while with an N95 the flow velocity is lowered by 10 times and the diffusion is limited between 0.1 and 0.25 meters.