More than 2,000 GP surgeries, clinics and hospitals across the UK are in areas which breach safe pollution limits, with people breathing "toxic air" as they seek medical care, analysis suggests.
The British Lung Foundation says they are in areas where average levels of tiny particle pollution known as "particulate matter" or PM2.5 are above limits recommended by the World Health Organisation.
The particles, the majority of which come from road transport in urban areas, are linked to causing and worsening diseases including asthma, coronary heart disease, stroke, and lung cancer.
In Wales, 54 GP surgeries and three hospitals are in polluted areas, with Cardiff seeing the highest levels of PM2.5.
The UK currently meets legal limits for PM2.5 but these are more than twice as high as the recommended ceiling from the WHO.
The British Lung Foundation is urging the UK Government to put the WHO limit for PM2.5 into UK law in the forthcoming Environment Bill.