About 6 trillion cigarette butts are produced every year worldwide, leading to more than 1.2 million tonnes of cigarette butt waste. This is set to increase by more than 50 per cent by 2025, mainly due to an increase in world population.

Now an Australian research team is developing a way for cigarette butts can be turned into footpaths, bricks and other building materials - that have the added bonus of cooling our cities.