I am increasingly of the opinion that the wearing of masks is an imperative.  I have just finished listening to  a Czech doctor who said that it is mandatory to wear masks the moment they step outside and their infection rate is testimony to those measures.  I’m not talking about the N95 mask but the ordinary pleated mask.  Its all about risk reduction.

So far the debate has been about you not infecting other people when you sneeze and produce visible droplets.  Studies now seem to suggest that just normal breathing produces small, I suppose invisible, aerosolised viruses that hang around in the air.  And what about the basic virus itself – it’s essentially a large molecule, in fact a gas, albeit a heavy one.

Even though the mask cannot absolutely prevent the motion of the virus through it, there be a certain amount of trapping of the virus, particularly those that have been aerosolised.

The name of the game is risk reduction both to yourself and to others.
One virus does not make you sick.  Even without antibodies, the body defends itself in a variety of ways. For example, the surface of the skin is slightly acidic which acts as a barrier to most viruses and bacteria.  This is called the acid mantle.  There are probably numerous other passive defence mechanisms before the immune system kicks in.  Thus it takes millions of the buggers before you actually get sick.  (Although Monty Python sang ‘Every Sperm is Sacred’ in reality it takes millions of them to do the job)
The other aspect is not affecting orthers.  Its all about the re-infection coefficient, R.  An R of 2 means that each infected person infects 2 others and those 2 will infect 2 others each.  After 5 levels, 2^5 = 32 will have been infected.  after 10 levels, 1024 will have been infected.  Reducing this to 1.4, say, only 5.4 and 29 people will be infected respectively.  Thus a small reduction in risk has a dramatic effect on the trajectory of the epidemic.
The other advantage of the pleated mask is that it is easy to disinfect for reuse.  Washing, soaking in Jik or ironing will kill the buggers dead. (Personally I would not wash too much as it tends to mat the fibres).  If you are still not sure, you can spritz them with meths.  It’s double protection – like wearing 2 condoms.