>>Blue surgical masks have a maximum effective use time of 10 minutes, 20 at the most, as soon as they become saturated with water vapour they are useless at trapping viruses
They might not give the wearer much protection but they must prevent them spraying it about to some extent.
I saw an article today which confirmed what I have been assuming since distancing came in. If you are walking in somebody's slipstream, particularly if they are upwind, you need to be a long way back. Obvious really.
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