The UN summit on sustainable development is coming to a close in the Brazilian city of Rio de Janeiro.

It is 20 years since the original 'Earth Summit' set targets for improving the environment for everyone.

The crowded hillside neighbourhood known, Rocinha, is Rio de Janeiro's biggest slum with a population of 120,000.

The BBC's Science Editor David Shukman took a walk through the streets of Rocinha to see how life has changed there.