A new paper published in Science Magazine states the importance of masks bluntly:
Masks and testing are necessary to combat asymptomatic spread in aerosols and dropletsFrom: Reducing transmission of SARS-CoV-2
The article explains that the current 2 metre social distancing rule is based on studies into how far respiratory droplets travel from the mouth. But these studies were carried out in the 1930s and focused on relatively large, heavy droplets that fall to the ground in a few seconds. Scientists can now detect much smaller droplets that can stay airborne for up to 12 hours while following airflows and potentially reaching much further than 2 metres.
As the picture so graphically illustrates, masks can play a key role in reducing the quantity of airborne droplets expelled by the infected, while simultaneously reducing the exposure of the healthy.
It’s a clear win/win situation from a science perspective.