Analyzing the air quality of Beijing, Tianjin, and Shijiazhuang using grey Verhulst model

To predict the comprehensive air quality index, the data of comprehensive air quality index and environmental protection investment are analyzed in Beijing, Tianjin, and Shijiazhuang, respectively. Considering the different growth rates in environmental protection investment, comprehensive air quality index is predicted by grey Verhulst model. The results show that the government’s investment can promote the improvement of air quality to a certain extent. According to local conditions, the improvement of air quality not only relies on government investment, but also needs other ways to reduce the comprehensive air quality index.