Rising Trend of Air Pollution and Its Decadal Consequences on Meteorology and Thermal Comfort Over Gangetic West Bengal, India

Abstract

Indo-Gangetic Plain is a renowned hotspot of high-level air pollution for the last few decades. Beginning with the northern urban–industrial development, now the pollution sources have spread over its lower catchment at an alarming rate, covering the south of the state West Bengal. Subsiding winds have further escalated the pollution level over this state by carrying pollutants from the upper catchment. Responding to those two factors, the aerosol optical depth over the lower Gangetic plain in West Bengal often crosses a value of 0.6, with an emission of more than 130 metric tons of carbon dioxide annually. This region is mainly dominated by eight distinct land use classes and has diverse pollution sources from industrial emissions, vehicular emissions, domestic pollution to biomass burning. With the rapid urban–industrial progress, the pollution emission is at its high peak in recent history, but not enough remediation policies are taken till date with a poor pollution monitoring status. Outcomes of the WRF-CHEM model indicate an increase of 0.8 °C to 1.2 °C air temperature with 1.5 to 1.8 W/m² increase of sensible heat flux due to rising air pollution in the lower Gangetic plain of West Bengal. Vertical pressure–temperature profile as well as the boundary layer temperature and surface humidity are found to be affected by certain high pollution periods over the year. The altered atmospheric chemistry by anthropogenic pollution is often found to push the temperature–humidity index level from “mild stress” to “severe stress” category in pre-monsoon seasons, compelling the residents to feel an irritating level of thermal discomfort.

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