>The not over ear, but around the head instead masks that someone else mentioned sound like a good idea, but I've never seen them in the UK, so I never even knew such a thing existed.

Here is the 3M Aura N95 mask at Amazon UK: https://www.amazon.co.uk/AuraTM-Particulate-Respirator-Unval...

£59.65 for 20, so about 6-7x more expensive than in the U.S.