The corrosion of works of art by air pollution is described after an investigation of bronze, natural stone, painted window-glass and wall paintings. By the action of soot, dust and sulfur dioxode combined with humidity, bronzes became seriously damaged by the formation of different hydrated copper sulfates, which are rapidly removed by the rain. To find efficient methods for the restoration and protection of bronzes, a research program is supported by German foundations. Stone is affected more by crusts of soot and dust than by decomposition caused by SO₂. This decay is due more to natural weathering, which is intensified in air polluted surroundings. Effective methods for the preservation of stone are available, but the efficacy of all of them diminishes after some time and the treatment has to be renewed in order to prevent serious damages. Wall paintings on facades suffer from layers of soot on the surface and decomposition of the plaster caused by moisture. -- AATA