Impact of allocation factors on spatial disaggregation of road traffic emissions in Megacity Delhi

The traffic emissions have intensified with a rapid surge in urbanisation. A comprehensive estimation of these emissions coupled with spatial analysis is imperative for the development of mitigation strategies. This paper presents an approach for spatially disaggregating the on-road emissions based on different allocation factors across the megacity of Delhi at a resolution of 1 km × 1 km. The annual on-road emissions of PM, CO, NO_x, and VOCs for the base year 2018 are estimated as 9.58 Gg, 248.18 Gg, 102 Gg, and 386.92 Gg, respectively. The emissions are spatially distributed based on the three allocation factors: road density, population density and urban area. The results show that the Northeast and Shahdara districts of Delhi are the primary hotspots of all the emissions. Southwest and West Delhi also significantly contribute to annual emissions. The study reveals that the combination of the allocation factors will improve the spatial disaggregation of traffic emissions. The proposed methodology for disaggregating the emissions helps identify the significant emissions hotspots over a geographical region and develop source-specific mitigation strategies to reduce emissions.