Abstract:

Based on the daily air quality report and the corresponding meteorological data from 2001 to 2011 in Xi’ning, the characteristic of regional pollution, air quality and its influencing factors were analyzed. The results show that the inhalable particle is the main pollutant and air quality is dominant by excellent and fine grades in Xi’ning. Air quality has a clear seasonal change. It is better in summer, then in autumn and winter, while it is the worst in spring. The air quality is unstable in winter and spring, while it is stable in summer and autumn. The annual air quality changes significantly, and API is higher during winter heating period than during non-heating period. Sand-dust influencing index is in a declining trend in Xi’ning. Air quality is remarkably improved based on analysis of interannual variability. The air pollution is restricted by meteorological factors such as sand-dust days, precipitation, relative humidity and air temperature. Long-range transport of inhalable particulate matters from the northwest of Xinjiang and Gansu provinces, middle and west of Inner Mongolia and Qaidam Basin are important sources of air pollution in spring in Xi’ning.

Key words:  Air pollution index (API), Sand-dust influence index, Influencing factor, Backward trajectory