Indoor and outdoor microclimate case studies: the Trajan Column and Sistine Chapel

The Trajan Column has suffered both physicochemical and biological weathering, but their effects were different over the course of the centuries. A reconstruction of the past climate and pollution of Rome (both due to the varying number of inhabitants and to the volcanic activity of Vesuvius) and a comparison of the actual deterioration with replicas made in 1665 and 1861-1862 indicate that biological damage was dominant in the past. The results of field surveys carried out to investigate the daily and seasonal meteorological factors, the microclimate and the induced effects e.g., solar radiation and stone temperature (both observed and computed with a mathematical model), evaporation and condensation cycles, various deposition processes of airborne pollutants, and rainwater dissolution, are described. The microclimate plays a very important role in the conservation of the frescoes of the Sistine Chapel, for both physical integrity and protection against soiling. Experimental surveys were carried out in order to investigate how the local environment is disturbed, to analyze the various deposition processes that are induced by the microclimate and the presence of visitors, and to study and suggest mitigative interventions. Scientific results, problems arising from the presence of visitors and the management of the chapel, as well as some proposed remedies of general interest are discussed.