I feel that the government is to blame for not making ‘being exempt’ more official. There should be clear medical exemptions only for people not wearing face coverings. And really, if you wear a face shield, you can breathe perfectly well with asthma, COPD etc. Either we have a rule or we don’t. By the way, I don’t blame shopkeepers, bus drivers etc. if faced with a hostile group, not taking them on. Luckily, where I live, people seem pretty compliant.