The Scottish Government should create an official exemption card or badge for those who are unable to wear face masks for medical reasons, according to a charity.
An online survey conducted by joint charity the Asthma UK and British Lung Foundation Scotland found a third of its supporters have faced prejudice due to their inability to wear a face covering.
Responses to the survey included accounts of being refused taxi rides and entry to shops.
Some people with lung conditions said they are now too anxious to leave the house.
Face coverings are mandatory in shops and on public transport in Scotland.
One of the 710 respondents to the survey said: “I was criticised by people when I said my breathing gets heavy/harder to breathe when wearing a mask.
“They said they find it ‘uncomfortable’ to wear as well, so I should just get on with it.
“Other occasions include refusal of taxi rides and access to shops. The general understanding of it not just being discomfort or that I don’t want to wear one, but it is physically harder to breathe.
“On occasion when I have tried to use a mask I have needed my inhaler beside me for several hours afterwards.”
Asthma UK and British Lung Foundation Scotland have now called on the Scottish Government to create an official exemption badge or card to “help to reduce the confusion amongst the general public”.
The charity said there are currently several schemes and downloadable cards available, but the variety “may have contributed to the lack of trust placed in them”.
Joseph Carter, head of Asthma UK and British Lung Foundation Scotland, said: “With the introduction of mandatory face covering on transport and in shops we have received a large volume of calls to our helplines from those who are exempt.
“It is unacceptable that people are facing discrimination due to their medical conditions.
“We believe that the time is now right to introduce an official Scottish Government-backed scheme that would give the card or badge an elevated level of authority, and thus allow those unable to wear them to feel more confident to use public transport or to go to places where social distancing can be more difficult, such as shops.”
A Scottish Government spokeswoman said: “The guidance on the use of face coverings by the public is clear that it may not be appropriate for those who have a health condition or are disabled to wear a face covering.
“As the First Minister has said, no one should be abused or treated in an unacceptable way and those exempt under the regulations should not be made to wear a face covering or denied access to shops.
“Retailers can ask people to wear a face covering, but should be understanding when people tell them they are exempt and we do not expect staff to enforce the wearing of face coverings.
“We are asking people to take personal responsibility to do the right thing.”