The deposition of airborne particulate matter on the surface of historic buildings causes a number of physicochemical decay processes, leading to the deterioration of the building materials. Particularly in coastal areas, marine aerosol intensifies the process of weathering through the deposition of sea-salt particles, which is controlled by various environmental parameters. A study is being carr ied out at the medieval city of Rhodes, where most of the buildings are constructed of local sandstone, focusing on the revelation of the building material’s decay mechanism due to sea-salt aerosol. A specific interest is directed on the environmental factors that affect the deposition rate of sea-salt particles and enhance the weathering procedures. In order to address the environmental effect on historic buildings, meteorological data was collected and combined with the results obtained by monitoring the aerosols and the total deposition. Aerosols were collected using a 10-stage impactor and dry deposition was monitored on stone specimens. Stone samples, taken from dated positions, were examined in order to assess the deterioration degree and to study the total deposition rate. Th e components of the collected particulate matter were analysed by means of SEM-EDX in order to study their composition and physicochemical characteristics. The synergistic effect of sea-salt aerosol and anthropogenic airborne particulate matter is discussed through the results of the analyses. A correlation between the collected data and the environmental parameters that control marine aerosol production, its physicochemical transformation in the atmosphere and its deposition, is performed in order to explain the weathering phenomena that cause characteristic decay patterns due to soluble salt crystallisation. In the present paper the methodology used to monitor the environmental parameters and the production of aerosols is presented, the initial outcomes of the research are analysed and the targets set for its completion are presented.