Abstract: The vehicular emissions in metropolis greatly affect the population healthand the urban environment, and have been considered as one of key factors inurban development. An understanding of the urban traffic emissions,their diffusion and the future trends is important forthe improvement and maintenance of healthy urban air quality. This papergives a detailed review on the current status of urban traffic pollution,the characteristics of traffic emissions, and the predictionmethodologies, which may be useful and interesting to those who aredetermined to tackle the challenging tasks in urban environmental pollutioncontrol and improvement.