Works of art, exposed outdoors, which consist of stone, glass or metal are seriously damaged or already destroyed by air pollution. The decay of stone and glass, which also suffer from natural weathering, proceeds so rapidly that conservation using available, although not yet entirely convincing methods, should perhaps wait until better techniques are developed. In addition to stone conservation, the Doerner-Institute also investigates damages to bronze by air pollution, in order to develop restoration-methodsfor the great number of bronzes of the 16th century which are still outdoors in many German towns. For the protection of modern bronzes, coatings of wax or synthetic materials are tested. -- AATA