It's not my article, Steve! I only posted the link :-) There may be some flaws in it but it is the best I have seen and until I see something better, I shall follow the advice given there. If you want to see the background to the summary given in the article there is a fuller and more scientific piece here

It is beyond my secondary school science lessons but if you would like to read it and refute it in plain terms, I am happy to listen. Going back to an earlier point though, I think I will continue to wear the mask just to annoy Boris :-D