Critical Emissions from the Largest On-Road Transport Network in South Asia

Abstract

One of the major requirements of air quality management for a particular region or country is to understand the sources of emissions, particularly those from the dominant sectors. The on-road transport sector is one of the most important sources of pollutant emissions, as it is directly linked to economic growth, and the current study focuses on India, a nation that is currently experiencing very rapid development. In view of this, the present work develops an inventory of on-road vehicular emissions at 0.5° × 0.5° resolution (approx. 55 km) for a region in India, where a technologically-based dynamic emissions factor method has been used to for the last 20 years. This new inventory can not only provide improved estimates of emissions in recent years but also highlight the relative contribution of various vehicles, based on age, to the total emissions produced by the transport sector. In addition, inventories of the major air pollutants for on-road vehicles in India are developed for the base year of 2009 for the first time in this work. The total emissions from the transport sector are estimated to be 5.4 Tg/yr for NOx, 10.2 Tg for CO, 693.3 Gg/yr for PM and 5.54 Tg/yr for VOC, 240,000 kilometers of national, state and major highways in India are used to achieve a better spatial allocation of gridded on-road emissions, along with a vehicular density map in a GIS environment. The emissions data presented in this work will not only help in improving the simulated distribution of air pollutants in chemical transport models, but can also be used for air quality management in planning related mitigation strategies.