摘要：In recent decades, the built heritage has been degraded more than inthe past, which suggests that air pollution is one of the most dangerousagents in the degradation and alteration processes. Environmentalparameters, such as temperature, humidity, precipitation, direction andfrequency of winds, pollutants are the main causes of the deteriorationphenomena. Many studies have shown the close correlation betweenthese parameters and the formation and development of differentdegradation phenomena, such as black crusts, salts crystallization,detachments, erosion and alveolization. Black crusts and saltscrystallization represent the more common and dangerous ones.
