Region-wise and state-wise synthesis of vehicular emissions in India and their mitigation due to vehicular emissions standards

The implementation of different stages of Bharat Stage Emission standards (BSES) in India for reducing the vehicular emissions has been in different parts of the country at various points of time. A quantitative assessment of the emission standards in mitigating vehicular emissions at different Indian states will provide an estimate of achievable emissions standards for future norms. In this regard, the present work reports an assessment of the BS standards - BS-III, BS-IV and BS-VI in reducing the exhaust emissions in each of the Indian states. The assessment is performed through the survival fraction of the vehicles registered with different norms in the two age groups 2013-2017 and 2018-2022 and the corresponding emissions of NOx, CO, VOC, PM2.5 and BC. Over the years 2013-2022, the NOx emissions are the major contributors of vehicular emissions in all the states studied. Sur-prisingly, the BS-IV vehicles contributed significantly to vehicular emissions in particular states when compared to the BS-III vehicles. This urged to analyse the impact of meteorological and topographical factors on the vehicular emissions. The results revealed that the vehicular emissions are largely dependent on the temperature and altitude and with an increase in temperature and at high altitudes, the CO and VOC emissions are pre-dominant, even in regions with low vehicle population. This finding therefore indicates that the emission limits are not the same for all over the country and meteorology dependent emission limit should be included in framing the vehicle emission norms.