Surface PM_2.5 Air Pollution in 2022 India: Emission Updates, WRF-Chem Model Evaluation, and Source Attribution

Abstract. India experiences some of the highest PM_2.5 concentrations globally. Understanding the spatiotemporal variations of PM_2.5 and its source attribution requires robust air quality modeling supported by up-to-date emission inventories. Here we present the first WRF-Chem model evaluation and source attribution analysis for India for 2022, supported by updates in sectoral emission inventories and model schemes. We incorporate an updated residential emission inventory reflecting recent transitions to cleaner fuels in Indian households and develop a plant-level inventory for Indian coal-fired power plants. Further major improvements include model updates to the secondary organic aerosol scheme and an improved representation of near-surface pollutant mixing. Collectively our improvements result in a simulation with annual PM_2.5 bias of only 0.2±16.9 μg/m³ (0 ± 31 %) across 288 surface monitoring sites in South Asia. We find that, compared to earlier studies, in 2022 India's residential sector remained the dominant source of PM_2.5 in the Indo-Gangetic Plain, but nationally ranked second in population-weighted (PW) mean PM_2.5 concentrations contributing 15 % (7.3 μg/m³). Instead, industrial emissions emerged as the largest domestic contributor to national PW mean PM_2.5 (18 %, 8.6 μg/m³), with urban hotspots including Delhi and Mumbai. The power sector contributions ranked third nationally (13 %, 6.1 μg/m³) and was particularly influential in central India. Transboundary transport contributed more than any individual domestic source nationally (27 %, 12.8 μg/m³). These findings highlight the benefits of India's partial residential sector transition toward cleaner fuels, while underscoring the growing consequence of industrial and power sector emissions that have limited pollution controls.