Microclimatic problems of Orvieto Cathedral

The climatic features of central Italy are described to introduce the microclimatic monitoring near the Orvieto Cathedral. The relative humidity is quite high (>90%). The water condensation occurs on stone surfaces in winter or at night; the water absorbed causes the biological decay, and is linked to natural causes (solar radiation, rain, wind, microorganisms); the air pollution is negligible in the dry phase.