84 Cracow 1991 35. The participating States believe that taking concerted measures to protect the common cultural heritage from environmental damage is necessary. To this end they will consider establishing or joining networks for the collection of data and co-ordination of research. They will endeavour to co-ordinate policy decisions and undertake direct measures to reduce the impact of air pollution and other degradation on the common cultural heritage. 36. With a view to protecting cultural sites in urban environments, measures will be taken by the participating States to counteract the effects of pollution on the architectural complexes of threatened cities; to restore, preserve and revitalize historical urban centres; and to safeguard sites and protect them from damage due to the increasing flow of tourists. 37. The participating States note the importance of protecting the cultural landscape, particularly in villages and rural areas, from the danger inherent in changes in the pattern of economic activities and in the impact of pollution, with a special view to protecting dwellings and coherent ensembles of the everyday living environment. 38. In view of the contribution which natural history can make to our understanding of the world of today and its evolution in the future, the participating States will endeavour to foster the preservation and interpretation of natural history sites and collections. 39. The participating States note the importance of safeguarding public and private parks and historical gardens, as works of humanity and nature, due to their historical, botanical and social interest, including their decorative and architectural elements. 40. The participating States will endeavour to safeguard and protect the archaeological sites located on their territories, including sites located under water. They will bear this aspect in mind during regional development operations which are likely to be a threat to sites which have not yet been scientifically surveyed, excavated or restored. 41. They stress the need for co-ordination of the activities of international organizations and institutions, such as the Council of Europe and UNESCO, in order to contribute to the full development of cultural co-operation among the participating States. Bearing in mind the need to avoid duplication of effort, the participating States will co-operate closely within the competent international organizations to which they belong. (…)