On the basis of a theoretical model suggested by O. Vittori and his coworkers, the oxidation of SO₂ in CaSo₄ on Venice marble surfaces has been investigated by nondestructive techniques (radiotracers and optical methods). A climatic chamber has been built up to reproduce the Venice environmental conditions. Samples of Venice marble have been subjected in the chamber to cycles of heating and cooling in ₃₅SO₂ atmosphere with high relative humidity. Other samples have been taken in wet conditions to compare them to the previous ones. Some sample surfaces were partially covered by Venice air particles and FeC1₂ as SO₂ oxidation catalyzers. This kind of stone sickness, that is the SO₂ transformation in stable CaSO₄ seems mainly to be caused by the pollution particles as well as the effect of atmospheric conditions: heating and cooling of Venice stone and marble surfaces. Author's addresses: A Breccia, Cattedra di Chimica Generale ed Inorganica, Facoltà di Farmacia, Università degli Studi di Bologna, Via Selmi 2, Bologna, Italy. S. Fuzzi and O. Vittori, Microfisica dell'Atmosfera, C.N.R.-I. F.A., Via de' Castagnoli 1, Bologna, 40126, Italy. -- AATA