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Air pollution impacts on human health are of serious concern in northern India, and over the Delhi National Capital Region (NCR) in particular. The Kharif crop residue burning (CRB) is often blamed for degradation of Delhi-NCR's seasonal air quality. However, the concentration of fine particulate matter (PM2.5) remained stable in Delhi, while the fire detection counts (FDCs) from satellites over Punjab and Haryana declined by 50% or more during 2015–2023. We measured PM2.5, carbon monoxide (CO) and related parameters over Delhi-NCR, Haryana and Punjab from a network of 30 low-cost sensors (CUPI-Gs) in a selected period (September–November) of 2022 and 2023. Measured PM2.5 showed lower concentration in 2023 compared to 2022 at Punjab and Haryana sites, in compliance with FDC reductions. Using the CUPI-G measurements, airmass trajectories, particle dispersion and chemical-transport model simulations, we show that the CRB emissions over Punjab contributed only a meagre ~14% to the overall PM2.5 over Delhi-NCR during October-November 2022. This indicates that there exists only a very weak coupling between PM2.5 mass over Delhi-NCR and the CRB over Punjab, highlighting the effectiveness of the Graded Response Action Plan (GRAP) in controlling air pollution in the region. [ABSTRACT FROM AUTHOR]

Elevated emission of particulate matter (both PM2.5 and PM10) is not limited to urban areas. It's the major pollutant that drives the air quality across the Indian sub-continent as well as across the globe with adverse health impacts. Moreover, India is home to many polluted cities in recent years that are among the list of most polluting cities in the globe. Therefore, the identification of sources of particulate matter and their quantification along with spatial variability has become of paramount importance from the modelling point of view. The present work is an attempt to develop a high-resolution (~10kmx~10km) national inventory of particulate (both PM2.5 and PM10) pollutants for India for the base year 2020 using IPCC methodology. The study quantifies the emission load from all possible sources in the county using the best possible resolution activity data and bottom-up approach. The estimated annual emission for PM2.5 and PM10, are calculated to be 15.8 Tg/yr, and 8.3 Tg/yr respectively. The developed emission dataset is publicly available on Zenodo at https://doi.org/10.5281/zenodo.7885103 (Sahu et al., 2023). Transport-driven windblown road dust remains the dominating source of PM10 emission, while transport and industry are the most important sources of PM2.5. The unattended anthropogenic source - municipal solid waste burning is found to be emerging as a new threat followed by crop residue burning. The developed new surface dataset has formulated a few recommendations of possible mitigation strategies for India and would be a critical tool for modelling studies. [ABSTRACT FROM AUTHOR]

The Indian capital megacity of Delhi is reeling under deteriorating air quality, and control measures are not yielding any significant changes, mainly due to a poor understanding of sources of emissions; hence, priority option in mitigation planning is lacking. In this paper, we have made an attempt to develop a spatially resolved technological high-resolution gridded (∼0.4km×0.4km) emission inventory for eight major pollutants of the Delhi region where high-resolution activity data of all possible major and unattended minor sources are generated by organizing a mega-campaign involving hundreds of volunteers. It is for the first time that we are able to estimate the decadal growth in emissions of various pollutants by comparing newly developed 2020 emissions with SAFAR (System of Air Quality and Weather Forecasting and Research) emissions of 2010 using the identical methodology and quantum of activity data. The estimated annual emissions for PM 2.5 , PM 10 , CO, NOx , VOC, SO2 , BC, and OC over the Delhi National Capital Region (NCR) are estimated to be 123.8, 243.6, 799.0, 488.9, 730.0, 425.8, 33.6, and 20.3 Ggyr-1 , respectively, for the year 2020. The decadal growth (2010–2020) in PM 2.5 and PM 10 is found to be marginal at 31 % and 3 %, respectively. The maximum growth is found to be in the transport sector followed by the industrial and other sectors. Maximum decadal growth found for the pollutants BC, OC, and NOx is 57 %, 34 %, and 91 %, respectively. The decadal shift of sectorial emissions with changing policies is examined. The complete dataset is available on Zenodo at 10.5281/zenodo.7715595 (Sahu et al., 2023). [ABSTRACT FROM AUTHOR]