There are over three billion people living in cities worldwide.
2
There are a lot of traffic in most cities.
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There enough basic facilities in some cities.
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50 years ago the population of Dubai was under 100,000. Today there over two million residents.
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In some urban areas there any green space.
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There too many people living in slums – 15% of the world population.
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In slum areas there often only one toilet per 5,000 people.