alessandra orofino: it includes rapid expansion of cities.veloping world, one third of the population is living in slums, something none of us should accept as we grow and think about a planet in which we want to live. narrator: slums are a result of rapid, unplanned expansion. today, an estimated 863 million people live in slums. if the slum dwellers in india were a separate nation, they would be the 13th most populous country in the world. but slums are not always hopeless places. alessandra orofino: the poor are not just sitting and waiting for the government to do something for them, they are creating their own environment. in rio, most of that infrastructure was built by them. so there is a level of do-it-yourself that you see in more poor neighborhoods than neighborhoods precisely because the government wasn't there. narrator: this means slums must be handled delicately by urban planners. alessandra orofino: what do we do with areas that were developed by communities but lack infrastructure? even if we are assuming goodwill, in terms of