Source attribution modeling of PM2.5 and CO in Indore, India

Indore grapples with severe air quality challenges due to rapid urban development, posing significant public health risks. To investigate the source contributions, it is vitally important to distinguish the contribution of local emissions and regional emissions. This study employs the WRF-Chem model in tracer mode to discern the contributions of PM2.5 and CO emissions from diverse regions over Indore, India. We identify the different high-emission contributing local and transboundary 25 regions and sources of particulate matter and CO emissions in Indore using WRF-Chem model during 2019. The model utilizes a two-domain configuration. Model simulations successfully capture the spatial distributions of key meteorological parameters over the domain when compared to various datasets such as IMERG, MOPITT, and ERA5. Results reveal that CO anthropogenic sources, both local and transported across domain boundaries, significantly contribute to concentrations in Indore. While the general spatial distribution of simulated CO aligns with MOPITT, simulated values are comparatively lower due to the exclusion of secondary sources and biogenic emissions. PM2.5 in Indore itself is a main source of emissions with contributions exceeding 16% throughout the year, whereas biomass burning emerges as the primary source of PM2.5 during specific months, with a consistent contribution observed throughout the year within the Indore district boundary. From an effective mitigation strategy perspective, further, we have combined local emissions and CAMS emissions in the model for the quantification of various pollutants over the Indore region. We estimated the various sectoral contributions from residential, industry, transport, DG sets, eateries, brick kilns, and crematoriums with high spatial resolution using Weather Research and Forecasting with a Chemistry model.