France, Sept. 26 -- Paris City Hall estimates that between 1.5 and 2 billion cigarette butts are discarded on the capital's streets each year, costing around €10 million annually to clean up.

"We need to take into account how popular Paris is as a city. It's the most visited city in the world," says Konstantinos Despotidis, founder of Creatives of Tomorrow, a Paris-based non-profit dedicated to climate action and sustainability.

"That's why we're here, to support Paris City Hall as much as we can by collecting litter here and there."

His group organises regular cleanups where volunteers meet to pick up waste.

"We try to sort the litter out in cigarette butts and glass bottles, plastic. And then we give them to dedicated organisa...