Food delivery app Deliveroo is handing out free air quality masks to mark Clean Air Day today.
The gesture is part of a scheme to improve cyclist protection against air pollution and signal its support for the nationwide campaign.
More than half of the app's 25,000 UK riders use bicycles to make deliveries.
Deliveroo said it would hand out the masks - made by the Cambridge Mask Company - to riders in London, Birmingham, Manchester and Glasgow, before making them available to the cycling general public later in the summer.
The scheme aims to raise awareness around air pollution and healthier cycling.
Deliveroo director of policy Emma Simmonds said: "Deliveroo riders are at the heart of everything we do and we want to support them however we can.
"Riders are out in the community and on the roads every day bringing people their favourite meals.
"We know our riders love riding but that also means, just like other cyclists, they face the challenge of poor air quality in some parts of the UK.
"We are delighted to be supporting another exciting British start-up. Cambridge Mask Company have come up with an innovative solution to tackling this problem and we think everyone, especially our riders, should be able to try out these masks.
"Deliveroo is determined to support efforts that make our cities cleaner and safer to ride in."
Christopher Dobbing, chief executive of the Cambridge Mask Company, said the rising impact of air pollution meant more action was needed.
"Ninety-eight out of every 100,000 deaths are a result of polluted air so we are incredibly excited to be part of a new custom branded mask being distributed with Deliveroo," he said.
