English law makes it clear that you don’t need to wear a mask on public transport or in shops if you have a “reasonable excuse”.  It could be argued that having found this page means that wearing a mask has a negative impact on you and therefore you will be exempt.  The law gives some examples, but there are many others which are not defined.

Note that you don’t need to have a disability or a letter from a doctor not to wear a mask – you merely have to state that you have a reasonable excuse.

You can obtain an exemption card to show if it helps (but you are not compelled to have one of these – you can just state that you are exempt).

The UK Government website states:

“Exemption Cards – 

Some people may feel more comfortable showing something that says  they do not have to wear a face covering.This could be in the form of an  exemption card, badge or even a home-made sign.

This is a personal choice and is not necessary in law.

Those who have an age, health or disability reason for not wearing a  face covering should not be routinely asked to give any written evidence  of this. Written evidence includes exemption cards.”

Source:  https://www.gov.uk/government/publications/face-coverings-when-to-wear-one-and-how-to-make-your-own/face-coverings-when-to-wear-one-and-how-to-make-your-own