I was travelling most of the day yesterday, mainly in environments where mask wearing was obligatory, but it also included a 30 minute walk in sunshine. I woke today with a sunburnt nose and cheeks, exactly where my mask had been. It's been puzzling me all morning as I wear SPF 50. Suddenly realised that the friction of the mask must have removed all the sun cream and the top surface of skin hence the mask shaped sunburn!
Just wanted to warn people about this if you haven't already thought of it, and to suggest reapplying your cream if you've had a mask on. Might save you from looking as ridiculous as I do right now.