There should be no exemption from wearing a mask, given the current crisis. All the exemptions are excuses really. It's a thin piece of material. All the weak excuses about asthma, or some phobia are just - the dog ate my homework style of excuses.
You could even wear a mask over the tubes up your nose, if you are on oxygen, and breathing wise, if you need to be on oxygen, then you don't get much more ill than that.
You could even wear a mask over the tubes up your nose, if you are on oxygen, and breathing wise, if you need to be on oxygen, then you don't get much more ill than that.