Whither urban planning? Sir: In Karachi, just opposite Qayyumabad on the Korangi-Defence route, a concrete mixing plant has been operating for over a year. This plant is one of the main contributors to pollution in the area in a city where pollution is already well above acceptable levels.Why are the concerned authorities allowing such projects in the city when the norm is to locate such operations well outside the main city. Cities like New Delhi are making great strides in managing their pollution problem while our city governments are busy approving dirty industrial projects inside the city. The city government of Karachi should make serious efforts in shifting as many polluting industries as they can outside the city, or at least away from residential zones.INAYATULLAH SHEIKHKarachi