Sectoral impacts of anthropogenic emissions on particulate matter over western India: Inferences based on regional modelling.

Air quality over western India is driven by natural mineral dust emissions, originating from the Thar Desert and middle-east, alongside diverse local anthropogenic emissions as well as pollutant transport from the Indo-Gangetic Plains (IGP). Regulating the anthropogenic emissions can be an effective strategic means to manage regional air quality. However, this requires a detailed understanding on the segregated impact of major anthropogenic sectors and identifying the dominant sources during different seasons. In this regard, numerical simulations have been performed to quantify the impact of anthropogenic emissions from major sectors (power, residential, transportation and industrial) on fine (PM2.5), coarse (PM2.5-10) particulate matter and aerosol optical depth (AOD) over western India. High-resolution simulations (12 km x 12 km) have been performed using WRF-Chem v3.9.1 for winter and post-monsoon conditions (January and November, 2019) using anthropogenic emissions from EDGAR v5.0 inventory. Model results show that during winter, residential sector had strongest impact on PM2.5 concentrations (45%), followed by power sector (17%). In contrast, the power-sector impacted more strongly during the post-monsoon period (29%), with also a large impact by the industry sector (22%). For PM2.5-10, residential sector is found to be the dominant source in both winter (39%) and post-monsoon (25%) consistently, followed by power generation and industry sectors. The transition of sector dominance is driven by seasonal changes in the anthropogenic emissions and atmospheric photochemistry. Model simulations further revealed spatial heterogeneity in the sectoral dominance over local scales for PM concentrations which contrasted with that for direct emissions. This demonstrates key roles of secondary formation and dynamics in governing the regional air quality. The study provides model-based insights to assist formulation of more effective mitigation strategies over western India.