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Abstract

8 different natural stone types were exposed to exhaust gas under laboratory conditions to assess urban stone damage. 3 cm in diameter cylindrical test specimens were made from travertine, non-porous limestone, limestone, rhyolite tuff, sandstone, andesite, granite and marble. The samples were exposed for 1, 2, 4 and 8 hours to exhaust gas that was generated by compression ignition internal combustion engine. The exhaust emission was measured. The operating conditions of the engine were documented and several parameters (weight, density, ultrasonic pulse velocity, capillary water absorption, porosity) were measured before and after exhaust gas exposure. The tests indicate that despite the deposition of soot on the surface a significant material loss was recorded at rhyolite tuff (2m%) and at andesite (1m%). The penetration depth of soot was also different for different lithologies. A correlation was found between the ultrasonic pulse velocity and density of tested stones.

⎯ Despite the air quality improvement, air pollution is still a severe problem in Budapest, and the city is one of the most polluted capitals of Europe. Dust has an adverse health effect, and it also causes aesthetic changes to buildings. Dust contributes to the damage of stone and may also result material loss. The paper analyzes the composition of dust and also describe its flow patterns in the city center of Budapest. The study area is located in one of the most polluted areas of Budapest, at Margit Boulevard. Dust samples were collected from the facades of buildings. Samples were analyzed with particle size analysis with laser diffraction, point counting of particles by optical microscopy, and X-Ray Diffraction (XRD). To simulate the airflow and the dispersion of particulate matter (PM 10), a computational fluid dynamics code called MISKAM (Mikroskaliges Strömung-und Ausbreitungsmodell-microscale flow and dispersion model for built up areas) was used. The results suggest that dust deposition is controlled by the flow pattern. Analyzed dust samples contain wind driven mineral grains (quartz, dolomite) and also human activity related pollutants such as fly ash and soot.