India made "giant strides" helping people in slums like Dharavi, Mumbai
Nearly a quarter of a billion people escaped life in the slums over the past decade, the United Nations says.
The improvement was thanks largely to housing efforts in China and India, which made "giant strides", according to a report by the UN Habitat agency.
But the housing efforts were more than countered by world population growth and the rural exodus to cities.
So overall, the total number of slum dwellers actually increased from 776.7m to 827.6m, during the years 2000-2010.
SLUM REPORT: KEY FACTS
227m people rose out of slums in the years 2000-2010
China lifted 65.3m out of slums, and India 59.7m
But total slum dwellers rose from 776.7m to 827.6m
Sub-Saharan Africa has the most slum dwellers (199.5m) followed by South Asia (190.7m) and East Asia (189.6m)
The most unequal cities in terms of wealth are Buffalo City, Johannesburg and Ekurhuleni, all in South Africa
The most equal cities are Chittagong and Dhaka, in Bangladesh
More than half the world (3.49bn people) now live in urban areas
"Cities are growing faster than the slum improvement rate," warned Gora Mboup, co-author of the report, State of the World Cities 2010/11: Bridging the Urban Divide.
"Short of drastic action, the world slum population will probably grow by six million each year, or another 61 million people, to hit a total of 889 million by 2020."
In the past decade, China made improvements to the daily conditions of 65.3 million urban residents without shelter, while India lifted 59.7 million citizens out of poor housing.
It means the UN has already achieved one of its Millennium Development Goals (MDGs).
Under MDG 7, UN members pledged to make "significant improvement" in the lives of at least 100 million slum dwellers by 2020.
But overall, the world now has 55 million extra slum dwellers than it did in 2000, according to UN Habitat, also known as the UN Human Settlements Programme.
Half of that increase came from population growth in existing slum homes; a quarter by rural flight to the cities; and a quarter by people living on the edge of cities whose homes became engulfed by urban expansion.
The report's authors described a house as a slum if it lacked at least one of these five amenities:
- a permanent structure
- less than three people sharing a room
- access to water that was sufficient, affordable and could be obtained without extreme effort
- a private toilet or a public one shared with a reasonable number of people
- secure tenure