Assessment of Vehicular Pollution in China

As the motor vehicle population in China continues to increase at an annual rate of ~15%, air pollution related to vehicular emissions has become the focus of attention, especially in large cities.There is an urgent need to identify the severity of this pollution in China.Based on an investigation into vehicle service characteristics, this study used a series of driving cycle tests of in-use Chinese motor vehicles for their emission factors in laboratories, which indicated that CO and HC emission factors are 5-10 times higher, and NO x 2-5 times higher, than levels in developed countries.The MOBILE5 model was adapted to the Chinese situation and used to calculate the emission of pollutants from motor vehicles.Results show that vehicle emission is concentrated in major cities, such as Beijing, Guangzhou, Shanghai, and Tianjin.Motor vehicle emissions contribute a significant proportion of pollutants in those cities, with contribution rates of CO and NO x greater than 80% and 40%, respectively, in Beijing and Guangzhou.Urban air quality is far worse than the national ambient air quality standard.In conclusion, although China has a relatively small number of motor vehicles, most of them are concentrated within metropolitan areas, and their emissions are closely related to urban air pollution problems in large cities. IMPLICATIONSAlthough the traditional air quality problems in Chinese cities were characterized as coal-smoke type, motorvehicle-related air pollution has received intense concern in recent years, especially in large cities.As the population of motor vehicles in China is expected to continue to increase at a high rate, there is an urgent need to identify the severity of this pollution in Chinese cities.By conducting emission factor tests in laboratories for in-use vehicles, a methodology of real-world vehicular emission estimation can be constituted, and the emission contribution rate of motor-vehicle sources can be further calculated.Such analysis and its connections to urban air quality will form a basis for the development of a national control strategy to reduce motor vehicle emissions.