The empty buildings are vandalized. Gap sites where buildings have been knocked down was turn into the wasteland. The factories and housing were in the same areas air, the problem of noise and water pollution would be resulted commonly.
Urban decay (or inner city decay)are mostly occurred in the inner city or mixed zone which is the area that near to the city centre (the CBD). The oldest developed area is inner city, for examples, Sheung Wan, Wan Chai and Yau Ma Tei. And lack of maintenance of the inner city is the main causes of the urban decay. There are some factors that cause the occurrence of urban decay. First, the owners or wealthier people who lived in the inner city have moved out, only the new immigrants or low-income group residents left. They only earn a low income with a low living standard. Second, the old pre-war buildings were out of repair or with a poor maintenance. The owners are willingness to spend the money for maintenance of the buildings, and the tenants do not afford to spend money on it also. So no capital for building’ s maintenance, they can only getting worse .Third, the owners further divided and subdivided the flats into cubicles and bed spaces illegally for earning money, this worse the living condition. Forth, lots of traffic