A group of people ride their bikes around Cairo, Egypt to promote cleaner transportation methods on World Environment Day in Cairo June 5, 2010.
The purpose of World Environment Day is to raise awareness of environment issues and encourage action.
Cairo, the largest and most densely populated city in Africa and the Arab world, has the only subway on the African continent. The two lines that comprise Cairo Metro serve 700 million passengers annually. The transport capacity of Cairo Metro and the other public transportation options is about 4.9 million journeys per day, which is 3.5 million short of what’s required. The result: perpetually congested traffic as commuters take private vehicles and taxis to work, as well as choking air pollution.