ABSTRACT
Black soiling of building materials is a visual nuisance resulting from the darkening of exposed surfaces by the accumulation of particulate matter and it is related to the surface area covered by particles (Haynie 1986). Consequently, the deposition of urban particulate matter onto the surfaces of buildings has long been a cause of concern. Horace complained of the blackening of buildings in Ancient Rome. A complaint repeated in England 1600’s. John Evelyn was particularly concerned how this affected the appreciation of architecture. By the 19th century it was said to cling to buildings of London like ivy.
