Wearing masks in shops will become compulsory in the U.K. Next week.

As far as I understand, and I'm quite happy to be corrected with some real science, viruses (being living organisms) require water to survive.

The most common way that airborne viruses spread is within water droplets or aerosols expelled by infected people or animals. Not all, of course, because a very small sized virus can also survive for a short while on its own and not floating in water - presumably it could penetrate a mask more easily too. That is a smaller risk as the virus dies much more quickly.

A mask which prevents most of these water particles from being ingested will reduce the risk of being infected. REDUCE not PREVENT, as these particles will eventually penetrate most masks, can reach the eyes anyway, or can actually survive on the mask itself for some time.

So, I don't believe that wearing a mask will prevent infection, but it's likely to reduce the risk somewhat.

Actually, its more about other people than what I think anyway. If other people would feel more relaxed if I was wearing a mask in a shop, then I will wear one. That's just politeness and a bit of concern for others, isn't it?