Gaseous air pollutants and its association with stubble burning: an integrated approach using ground and satellite based datasets and concentration weighted trajectory (CWT) analysis

Abstract

The increase in intensity of anthropogenic activities in the world has induced increase in vulnerability to natural and man-made hazards, especially in densely populated metropolitan cities. Delhi faces severe health and infrastructure related issues due to the deteriorated air quality that worsens with variation in seasonal meteorological conditions. This study aims to identify the spatial sources of pollution contributing to Delhi and understand the role of anthropogenic activities and meteorological conditions in pollutant levels of the city in different years and seasons. This study assesses the variation in pollutant levels of CO, NO2 and SO2 in Delhi using ground and satellite observation data from 2018 to 2022. The pollutant levels are compared to the meteorological conditions to assess the role of environmental conditions in the change in pollutant levels along with its association to potentially contributing anthropogenic activities in and around Delhi region such as stubble burning in Punjab in 2019. The study further uses meteorological data and pollutant concentration data to develop back trajectories and carry out WCWT analysis that helps us identify the spatial hotspots contributing to the pollutant levels in Delhi on annual and seasonal basis. The exercise is carried out at winter, Pre-Monsoon, Monsoon, Post-Monsoon and Annual timespan for 2019 for 100m, 500m, 1000m and 1500m height above ground level composited to identify the spatially contributing hotspots. This study identifies the clear contributing hotspots in different seasons of 2019 and its overlap with observed active fire areas. This can help us segregate areas with similar fire intensity and varying contribution extent to pollutant levels of Delhi.