Environmental catastrophes, civic activism and international agreements are regarded as having promoted a more general awareness also of the human environment since the 1960s. The main objective of environmental protection is to regulate the flows of matter in the built environment, in the towns, cities and industrial communities. Environmental protection here implies explicit and concrete reduction of hazardous emissions into the soil, water and air.

Environmental protection can be regarded as an institution consisting of the elements of awareness, organisation, scientific identification of problems, technological solutions, and results i.e. the improvement of the state of the environment. Awareness of problems, organization and scientific work to explore them are necessary per se, but without functioning environmental technology they are worthless and improvements to the environment remain impossible. The main means of water protection is biochemical wastewater purification plants. They have improved the state of the environment perhaps more than any other single innovation. The main objective of the project was to establish why certain cities built wastewater purification plants voluntarily at an early stage, while other did so only much later.