Black soiling of an architectural limestone during two-year term exposure to urban air in the city of Granada (S Spain)

► A two-year term aging test was carried out on a building limestone under different urban conditions. ► The soiling process depends on surface texture and local micro-environments. ► Stone soiling was due to soot and soil, dust particles and fly ash. ► The estimated soiling coefficients were slightly lower than in other cities of Spain. ► Gypsum crust was developed during the first year of exposure.