changzhi city, ambient air quality, fuzzy mathematics comprehensive evaluation method, influencing factors, spearman correlation coefficient method, Chemical engineering, TP155-156, Materials of engineering and construction. Mechanics of materials, TA401-492, Technology

[Purposes] Objective evaluations of urban ambient air quality and analyses of its influencing factors are of great significance for understanding of current air quality situation and controlling of pollutants. [Methods] In this paper, an ambient air quality evaluation method based on fuzzy mathematics comprehensive evaluation method was constructed on the basis of the monitoring values of pollution factor concentration for the ambient air quality assessment of Changzhi City, and Spearman correlation analyses were carried out between the primary pollution factor and other pollution factors. [Results] The results show that compared with AQI (Ambient Air Quality Index) and Nemerow index method, the fuzzy comprehensive evaluation method using the stepped membership function can evaluate ambient air quality more comprehensively. The ambient air quality of Changzhi City was gradually improving from 2017 to 2022. The primary pollution factor in Changzhi City is PM10, and it is correlated with PM2.5, SO2, NO2, and CO, and the correlations decrease in turn, but not with O3. Through the analyses of the time distribution characteristics of pollution factors, it can be found that the concentrations of PM2.5, PM10, CO, NO2, and SO2 increase in the fourth quarter of each year, while the concentrations of 5 pollution factors decrease in the second and third quarters of each year, and the concentrations of 5 pollution factors in the fourth quarter are higher than those in the second and third quarters of each year. During the outbreak of COVID-19, all pollution factors show decreasing trends, and the decreasing trend of CO concentration is the most obvious.