Pope Francis is visiting a slum on Nairobi's northwestern edge to press his call for adequate and dignified housing for society's most marginal, especially in burgeoning megacities like the Kenyan capital.

Francis has frequently insisted on the need for the three "Ls" — land, labor and lodging — and on Friday he's expected to focus on housing as a critical issue facing the world amid rapid urbanization that is helping to upset Earth's delicate ecological balance.

Kangemi is one of 11 slums dotting Nairobi, East Africa's largest city. The shanty itself has about 50,000 residents living without basic sanitation. Most of the capital's slums comprise a maze of single-room mud structures with iron-sheet roofing or cramped, high-rise buildings.

In the tin-roofed St. Joseph's parish, which serves the neighborhood of single-story mud brick shacks, children from the parish school, wearing T-shirts with Francis' photo on them, were singing hymns while waiting for the pontiff to show up.

Valarie Mamarome, 16, said she hopes Francis' visit will put an end to corruption, so rampant in in Kenya.

"It leads to people being poor," she said.

Emily Night, a mother of two who works at the parish's HIV counseling center, said that the pope's visit is giving hope to Kangemi residents who often cannot afford garbage pickup, or even the treatments necessary to purify water to make it safe for drinking.

She said that the city pipes in water only three days a week, Tuesday through Thursday, but it's not safe to drink.

"Some people don't have toilets in their homes," she said. "Those that do, maybe 50 people are using it!"

Francis referred to the problem of urban shanties in his speech to the African U.N. headquarters on Thursday, saying everyone has a basic right to "dignified living conditions," and that the views of local residents must be taken into account when urban planners are designing new construction.

"This will help eliminate the many instances of inequality and pockets of urban poverty, which are not simply economic but also, and above all, social and environmental," he said.

The message was keenly felt because the U.N. Habitat program, which seeks to promote adequate and environmentally sustainable housing, is based in Nairobi.

Francis raised the issue of environmental deterioration in cities in his landmark encyclical "Praise Be," saying many megacities today have simply become health threats, "not only because of pollution caused by toxic emissions but also as a result of urban chaos, poor transportation, and visual pollution and noise."

"Many cities are huge, inefficient structures, excessively wasteful of energy and water. Neighborhoods, even those recently built, are congested, chaotic and lacking in sufficient green space. We were not meant to be inundated by cement, asphalt, glass and metal, and deprived of physical contact with nature," he said.

After the visit to Kangemi, Francis is scheduled to meet with young Kenyans and hear of their problems with violence and simply trying to live their lives as Christians at a time of Islamic extremism.

Following the encounter, Francis heads to Uganda for the second leg of his trip, where he'll honor the country's Anglican and Catholic martyrs.

On Sunday, he is due to arrive in the Central African Republic, the most dangerous leg of the pilgrimage given the ongoing conflict between Christians and Muslims.

The Vatican spokesman, the Rev. Federico Lombardi, said Thursday night that plans hadn't changed and that the Bangui leg of the trip was still on.

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