Spatiotemporal variation of air pollutants and their relationship with land surface temperature in Bengaluru, India

Abstract

Rapid development and urbanization in most of the cities of the world have led to increased vehicular traffic, industrial activities, and construction. Air pollution in most cities of developing countries, like India, often exceeds the limits given in relevant national/international standards. Rapid urbanization in Bengaluru is causing increased air pollution and land surface temperature (LST). The present study examines the relationship of LST with air pollutants, meteorological parameters, surface indices, and selected urbanization parameters. The study also aims to find out the air pollutant have the maximum effect on LST during different seasons. Air pollutants and meteorological data were collected from air quality monitoring stations, while LST data of MODIS satellite was downloaded from the internet. Data for the period 2018–2022 was utilized for the current research. The results indicated that PM2.5 concentrations exceeded WHO standards, and Hombegowda Nagar (B9), Peenya (B5), and Bapuji Nagar (B4) were identified as pollution hot-spots. A strong association of LST with air pollutants and meteorological parameters was observed during the winter season (R2 = 0.87 to 0.91), which was stronger than the corresponding association during summer (R2 = 0.72 to 0.79). The association further improved after incorporating spectral indices (NDVI and NDBI), global population density (GPD), digital elevation model (DEM), and road line density (RLD) and a very strong association was obtained (R2 value of 0.91 in summer and 0.96 in winter). The study also revealed a strong relationship between the Urban Heat Island index and the combination of all parameters, both for urban and rural areas as well as during both the summer and winter seasons. PM2.5 and SO2 were identified as the main air pollutants affecting LST variations during the summer season, while NO2 and CO were more influential during the winter season. The study concludes that variation in the LST of an area is governed not only by the surface characteristics but it is also affected by air pollutants and meteorological conditions as well as conditions of urbanization that can be represented by different parameters/indices. The findings of this study hold significant implications for future scientific research, and it may pave the way for the integration of effective mitigation strategies to combat the dual challenges of increasing LST and air pollution in urban areas.