Review of environmental and air pollution impacts on built heritage: 10 questions on corrosion and soiling effects for urban intervention

Abstract

Abstract For many decades, countless studies have been performed regarding the effects of the environment on traditional building materials, presenting methods to mostly quantify phenomena such as the corrosion of metals, stone degradation and soiling. Driven by concerning levels of air pollution in the late 1980's, many large international programmes such as the ICP-Materials, MICAT and ISOCORRAG have been testing worldwide material behaviour when exposed to acidifying pollutants, causing corrosion of metals and stone recession. Numerous individual studies have also contributed to a higher understanding of pollution effects on materials, including soiling studies. The methodologies mostly consist of open exposure of standard samples, either for short, mid or long periods, followed by a statistical analysis of the results, in order to develop accurate prediction formulations used for mapping exercises and to determine areas at risk. Considering all the available information, the contribution of this work is to perform an extensive bibliographic review, organized in the form of 10 basic questions that attempt to present and describe the effects of pollution on materials and practical ways to determine risk areas at urban scales and implement well-supported pollution mitigation strategies. The answers to these questions always take into consideration a more practical approach towards the identification of potential risk and subsequent intervention. Additionally, a new methodology regarding the assessment of environmental effects on actual buildings is discussed for the preservation of historic city centres, through the identification of potentially vulnerable buildings regarding deterioration effects by atmospheric corrosion, soiling and stone degradation.