Urbanization is one of the greatest health challenges facing with world in the 21st century. Today, over 3 billion people live in cities. Between 1995 and 2005, the urban population of developing countries grew by ~165,000 people every day [1]. In 2007, the world’s population living in cities actually surpassed 50% for the first time in history. As city populations around the world continue to grow, unplanned or mismanaged urbanization can have health security and safety consequences.