Diagnosis of surface damage induced by air pollution on 20th-century concrete buildings

The present work focuses on the impact of anthropogenic multi-pollutants on modern concrete buildings exposed in two different European urban areas: Centennial Hall in Wroclaw (Poland) and Casa Galleria Vichi in Florence (Italy). Through a range of analytical techniques the complete characterization of the damage layer collected from the buildings under study has been achieved for the first time, including quantitative measurements of the carbon content. The experimental results allow the identification and prioritization of the air pollutants responsible for the surface deterioration, finding gypsum to be the main damage product on surfaces sheltered from rain runoff, with embedded particulate matter, especially carbonaceous particles, responsible for darkening of the building walls. The discrimination of carbon fractions shows different concentrations of elemental and organic carbon within the damage layers, depending on the location of the buildings. This step is essential for identifying the anthropogenic sources causing deterioration on the buildings, including the aesthetic impairment of surfaces. The contribution of air pollutants is also reflected by the elements found in the damage layers, while the evaluation of the enrichment factors is useful for identifying the elements of anthropogenic origin.