RTEII: A new high-resolution (0.1° × 0.1°) road transport emission inventory for India of 74 speciated NMVOCs, CO, NOx, NH3, CH4, CO2, PM2.5 reveals massive overestimation of NOx and CO and missing nitromethane emissions by existing inventories

• Published in: Atmospheric Environment: X Vol. 11; p. 100118
• Main Authors: Hakkim, Haseeb, Kumar, Ashish, Annadate, Saurabh, Sinha, Baerbel, Sinha, Vinayak
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2021; Elsevier
• Subjects: Acetaldehyde; Air quality; Emission inventory; India; Road transport; VOC; Emission inventory; Air quality; Road transport; VOC; Acetaldehyde; India
• ISSN: 2590-1621; 2590-1621
• DOI: 10.1016/j.aeaoa.2021.100118

21 of 30 most polluted cities for particulate matter (PM2.5) are in India, yet the distribution, identity and emissions of volatile organic compounds (VOCs) from traffic, which are PM2.5 and ozone precursors, remain unknown. Here, we measured emission factors (EFs) of 74 VOCs from a range of Indian vehicle-technology and fuel types. When combined with 0.1 ° × 0.1 ° spatially resolved activity data for the year 2015, toluene (137 ± 39 Gg yr1), isopentane (111 ± 38 Ggyr−1), and acetaldehyde (41 ± 6 Ggyr−1) were top 3-VOC emissions. Petrol-2-wheelers and LPG-3-wheelers emitted the highest VOCs (EFs> 50 gVOC/L) and had highest secondary pollutant formation potential, so their replacement with electric vehicles would improve air quality. EDGARv4.3.2 and REASv.2.1 emission inventories overestimated total road sector emitted VOCs due to obsolete EFs and activity data, in particular over-estimating ethene, propene, ethyl benzene, 2,2- dimethyl butane, CO, NOx while significantly under-estimating acetaldehyde. Nitromethane emissions were missing from previous inventories and with isocyanic acid and benzene contributed significantly to toxic emissions (summed total ~41 ± 4 Ggyr−1). Knowledge of key VOCs emitted from the world's third largest road-network provides critical new data for mitigating secondary pollutant formation over India and will enable more accurate modelling of atmospheric composition over South Asia. [Display omitted] •Emission factors of 74 VOCs measured for Indian vehicular categories including LPG and CNG vehicles reveal high acetaldehyde.•0.1 × 0.1° speciated VOC traffic emission inventory over India with updated activity data shows overestimate by inventories.•Petrol 2-wheelers and LPG 3-wheelers had highest pollutant emissions.