The impact of meteorological conditions on Air Quality Index under different urbanization gradients: a case from Taipei

Abstract

With the concentration of air pollutants increasing, air pollution has many hazards to the human body. Meteorology is the main factor affecting the diffusion of air pollutants. Studying the dynamic connection between them can provide references for the construction of urban air environment. In this research study, data from meteorological factors (temperature, humidity, wind speed, and rainfall) and air pollutants (PM2.5, PM10, SO2, CO, O3, and NO2) were collected in 2018 from the areas of Zhongshan, Shilin, and Yangmingshan of Taipei City. The Granger causality test was used to analyze the intrinsic dynamic relationship between meteorological factors and Air Quality Index (AQI). The results showed that: (1) the overall level of AQI in Taipei was good, and the main pollutant that contributed to AQI was PM2.5. (2) The range of AQI values in the three study areas were Zhongshan (downtown) > Shilin (suburbs) > Yangmingshan (outskirts). (3) In downtown Zhongshan, temperature and humidity were the Granger cause of AQI; in the suburbs of Shilin, humidity, and wind speed were the Granger cause of AQI; in the outskirts of Yangmingshan, humidity was the Granger cause of AQI. (4) The air pollution of Taipei was found to be mainly a process of self-accumulation and self-diffusion. The self-accumulation effect of AQI was more than 70%. Once the diffusion condition of air pollution deteriorated, it formed air pollution. (5) Wind speed was the main meteorological factor affecting AQI in downtown Zhongshan and the suburbs of Shilin, while the AQI in the outskirts of Yangmingshan was mainly affected by humidity. In the construction of urban air environment, the emission of air pollutants should be controlled and reduced, the construction of urban ventilation system should be strengthened, and the layout of urban space should be rationally planned to create a better urban air environment.