They're small, orange and usually squashed flat and, once you start noticing them, you see them everywhere.

Cigarettes are the most littered item in the world, with an estimated 4.5 trillion butts flicked into the environment each year.

Made of cellulose acetate, a plastic that takes years to break down, the filters are often washed from footpaths into drains, before ending up as pollution in waterways.

Richard Squires, also known as Buttman, is trying to stop that from happening.