Backpack pigeons monitor London air quality
A technology company has released ten pigeons wearing lightweight sensors to monitor pollution in London.
Plume Labs has fitted the birds with tiny backpacks which monitor nitrogen dioxide, ozone and volatile compounds.
Until Wednesday people can tweet their location to @PigeonAir and can find out how much pollution is registered in their area.
It is also possible to view the pigeons' flight movements on a live map.
The idea was originally submitted by Pierre Duquesnoy and Matt Daniels, of marketing and technology agency Digitas LBi, to Twitter's #PoweredbyTweets competition.
It was the winning entry in the "Solve a Problem" category and was exhibited during the London Design Festival at Somerset House.
Racing pigeons are being used for the project, with a vet on hand to check the pigeons do not suffer any distress.
Plume Labs said 10,000 people die from air pollution each year in London alone.
It said it hopes to "show Londoners how air pollution affects them, especially during rush hour" using the pigeon air patrol service.
The campaign aims to encourage Londoners to become beta testers for a wearable version of Plume Labs' air pollution measuring device.