It has just been published in the magazine Science, and the CDC (Centers for Disease Control and Prevention) has also emphasized that the risk of airborne infection indoors is twenty times higher than outdoors.
The aerosols exhaled by the carriers of covid-19 when they breathe, cough, speak, etc. spread through the air, favored by the currents created by air conditioning, and can remain in the air if the premises are not sufficiently ventilated. For aerosols, the safety distance of two meters, which was set as standard at the beginning, is not real, since its lightness allows them to move much further; it is estimated that up to five meters even.
Therefore, it is of vital importance to remind workers, as well as users of these places, of the mandatory use of masks to prevent contagion.