Application Of Grey Theory On Prediction Of Air Pollutants Concentration And Quality Evaluation In Northwest City

In this paper, GM (1,1) and equal-dimension grey filling model are compared by using of annual average concentrations of urban air pollution monitoring data,such as SO2,NO2, PM10 in Northwest. Prediction models of annual average pollutant concen-trations are established in Lanzhou, Xi'an, Xining, Yinchuan, Urumqi. Air quality lev-els are analyzed in each city use of gray statistical strategy. The type of urban air poll-ution is judged by burden rate, which is calculated by the Shanghai air quality index.The results showed that:The relative error of fitted value decreases at each time point by the equal-dimension grey filling model, and the fitting accuracy is gradually improved, it fits better than GM(1,1) model. Relative prediction error of the model is less than GM(1,1) model, indicating that the model's predictive ability can improve with the introduction of the new forecast data and removal of the old data.The trend of SO2 and NO2 increases while the trend of PM10 decreases in Lanzhou, Xi'an and Xining. Air quality of Lanzhou is in light pollution level. Air quality of Xi'an is in slight cleaning level. Air quality of Xining is slight cleaning level. The trend of SO2, NO2 and PM10 in Yinchuan will decreases slowly. Its air quality is in slight cleaning level. The trend of SO2, NO2 and PM10 increases in Urumqi. Its air quality is in light pollution level, and will begin to deteriorate gradually. Air quality of Northwest cities ranges between Grade 2 and 3, and will improve in future.Type of air pollution changes from coal burning pattern to mixed pattern in Lanzhou, Xi'an, and Urumqi. The type of air pollution in Xining is vehicle-exhaust pattern. The type of air pollution in Yinchuan is coal-burning pattern. Analysis of air quality with the Shanghai air quality index and gray statistical strategy produces quite similar results.