Coronavirus: 'Not everyone can wear a face covering'
Some people are exempt from wearing face coverings.
Shona Muraldo-Parks, who is from Hackney in east London, has asthma and wears a home-made "I have asthma" badge after a few uncomfortable encounters on public transport.
Transport for London (TfL) and the NHS are calling for people to be more understanding and considerate towards those who cannot wear a face covering.