EMRAS-2 (Environmental Modelling for RAdiation Safety, Phase 2) is an international comparison program, which is organized by the International Atomic Energy Agency (IAEA), in order to harmonize the modelling of radionuclide behavior in the environment. To do so, the urban contamination working group within EMRAS-2 has designed the hypothetical scenarios for a specified urban area. In this study, the importance of contaminated surfaces composing an urban environment was analyzed in terms of dose rate using METRO-K, which has been developed to take a Korean urban environment into account. The contribution of contaminated surfaces to exposure dose rate showed distinctly a great difference as a function of specified locations and time following a hypothetical event. Moreover, it showed a distinct difference according to the existence of precipitation, and its intensity. Therefore, if an urban area is contaminated radioactively by any unexpected incidents such as an accident of nuclear power plants or an explosion of radioactive dispersion devices (RDDs), appropriate measures should be taken with consideration of the type of surface composing the contaminated environment in order to minimize not only radiation-induced health detriment but also economic and social impacts.