'Clean lungs' have appeared on walls and pavements around Bristol - including City Hall - as part of an art-inspired publicity stunt.
The striking images were made by members of the anti-pollution Our Air Our City campaign, with a technique known as “reverse graffiti.”
A stencil is used to selectively clean away accumulated dirt and grime, creating a graphic illustration of the damage caused by the city’s air pollution.
Bristol's Luke Jerram - who is perhaps best known for his 'Play Me, I'm Yours' street pianos and Park Street slide in 2014 - is among those backing the campaign.
He said: “Most graffiti uses toxic spray painting materials, but the clean air campaigners are cleaning off pollution to make this imagery.
"They're cleaning up the city and making art from the absence of dirt and pollution.
"Now is the time for real leadership on all forms of air pollution, which includes cleaning up the city’s air, and preventing the expansion of Bristol Airport."
Studies have shown that airborne pollutants such as nitrogen dioxide and PM2.5 damage lungs and can lead to respiratory illnesses, as well as increased risk from Covid-19.
Bedminster GP Dr Patrick Hart is amongst those who have committed their support to the Our Air Our City campaign, to pressure the city’s governing bodies to take urgent and radical action.
Dr Hart explained: "The City Council have been dealing with a huge health crisis this past year. But our polluted air is another health crisis that has been going on for years - it’s just killing us more quietly."