ABSTRACT
Mortar sulphation may be defined as the interaction between atmospheric SO2 and these materials. The processes whereby pollutants in the air are deposited on the surface of buildings and similar structures are divided into two groups: dry deposition and wet deposition. In dry deposition, gaseous, aerosol and particulate species accumulate directly on a dry or wet surface; in wet deposition, pollutants cluster in cloud droplets and are deposited on surfaces in the form of precipitation (Lewry et al. 1994).
