Impact of meteorological drivers on air quality index: A case study from Delhi

Air quality is directly linked to human health and the sustainable development of economic and social systems. This study is based on the Air Quality Index (AQI) and meteorological data of Delhi from January 1, 2017, to December 31, 2024, and it analyzed the daily, monthly, and annual variability of AQI data. During the study period, the average AQI of Delhi was hovering around 210, and the average AQI in 2024 was found to be significantly better than in 2017. The moderate AQI days were found to be dominant in the study period. First time Vector autoregressive model, Granger Causality test, Impulse response function, and Variance decomposition tools were employed to understand the dynamics of AQI in relation to meteorological variables. The adjusted model was VAR (2), and the results revealed that air pollution in Delhi primarily resulted from its own accumulation and diffusion patterns. In the first 5 periods, the self-cumulative effect of AQI accounts for approximately 93.314 % and gradually declines to 81.089 % by the 16th period. Once the dispersion conditions deteriorate, air pollution will develop within five days. Considering the meteorological variables, Temperature (13.235 %) as an atmospheric thermal factor was found to be the overall highest influential factor affecting AQI in Delhi, followed by rainfall (2.127 %). Windspeed (3.271 %) contributes the highest in the 2 period to AQI among all the meteorological variables. Whereas relative humidity has a little influence on AQI and contributes <2 % in the entire 16 periods. The results provide insight into the air pollution dynamics in one of the world's polluted urban areas and incorporate an unconventional approach to readdress the issue and highlight important findings. Future research should address other anthropogenic factors.