Buy “Face Covering Exempt” Cards

The people that make and supply the sunflower lanyards, that help explain hidden disabilities, have now come up with face covering exemption cards.
If a medical condition, disability or other issue means you can’t wear a face covering or mask, you can send off for a card that explains it and fits in a standard lanyard, for just 55p.

https://hiddendisabilitiesstore.com/hidden-disabilities-face-covering.html