An outline is presented of the study carried out on the effect of the microclimate on the deterioration of the sistine chapel's paintings. This is of particular importance, since current cleaning is exposing the original surface of the murals to the chapel environment. One way of ensuring less dirt deposition would be by creating a still atmosphere inside the chapel (removal of underfloor heating system). Thermal maps illustrate the conditions before and after admittance of visitors. 5 references. -- ICCROM