Experimental field tests carried out during different seasons and conceived in order to evaluate the seasonal and diurnal variation of natural ventilation, turbulence, thermo-hygrometric variables and their gradients, are illustrated in the case study of the Michelangelo's frescoes in the Sistine Chapel in Rome. The main deposition processes (i.e., inertial impaction, thermophoretic and Stefan flows) acting on the frescoes are considered. The differences in these physical variables depend on the exposure to solar radiation, lighting techniques, architectural characteristics of the building, and management of the room (e.g., cleaning, warming, visiting hours). In particular, public enjoyment plays a fundamental role in the transport and deposition processes and in the conservation of works of art.