For many people urban areas are concentration points of environmental decay, where pollution, noise annoyance and congestion can mean a serious threat to human welfare and well-being. At the same time, however, it has to be recognized that – with some ups and downs – urbanization has become widespread around the world, so that at a macro level, apparently, the economies of scale in urban areas are by and large superseding the diseconomies and external costs of modern city life. Nevertheless, the environmental situation in many cities is a matter for concern, as demonstrated by health standards not only in the Third World but also in Europe.