Non-methane volatile organic compounds emitted from domestic fuels in Delhi: Emission factors and total city-wide emissions

In controlled laboratory conditions, 62 samples of domestic fuels collected from 56 grids of Delhi were burnt to quantify the emissions of 23 non-methane volatile organic compounds (NMVOCs), i.e., alkanes (11), alkenes (6), alkynes (1) and aromatic compounds (5). The domestic fuels used for residential activities were comprised of 20 unique types of fuel woods, 3 species of crop residue, dung cakes and coal. These fuels are primarily used for cooking and water/space heating during winters. The current study reports the total emission budget of NMVOCs from domestic burning over Delhi. Furthermore, this study also compares the differences in EFs of NMVOCs which are calculated for different burning cycles and sample collection methods. The EFs of NMVOCs calculated from the samples collected during the flaming stage using canisters were analysed for 23 NMVOCs and then compared with same species emitted from complete burning cycle. In addition to this, 10 consumption and emission hotspot grids were also identified in Delhi; based on the ground survey and laboratory simulated results. The total annual usage of domestic fuels for the year 2019 was found to be 0.415 Mt/yr (million tonnes) in Delhi. 12.01 Gg/yr of annual NMVOC emissions was calculated from domestic fuel burning in which the emissions from dung cake and fuel wood dominated with 6.6 Gg/yr and 5.4 Gg/yr, respectively. The EFs of NMVOCs calculated using canister and online collection method differ significantly from each other. The flaming stage presented enhanced emissions compared to the complete burning cycle by ~7 times which suggests that the method of data analysis and the period of sample collection play a pivotal role in the preparation of an emission inventory and estimating the budget

Long-Term (2012–2021) Variation in Carbonaceous Aerosols of PM2.5 at an Urban Site of Megacity Delhi Situated over Indo-Gangetic Plain of India

A long-term (January 2012 to December 2021) study on carbonaceous aerosols of fine particulates (PM2.5) was conducted over the megacity of Delhi, India, to evaluate their seasonal and yearly variations. During the entire study period, the observed annual mean levels (µg m−3) of PM2.5 and its carbonaceous components (OC, POC, SOC, EM, EC, TCM, and TC) were recorded as 126 ± 72, 15.6 ± 11.6, 9.3 ± 6.3, 6.4 ± 5.1, 8.2 ± 5.6, 7.3 ± 5.1, 33.2 ± 21.9, and 23.1 ± 16.5, respectively. On average, the CAs/TCM ratio accounts for 26% of PM2.5 concentrations. During the monsoon (minimum) and post-monsoon (maximum) season, significant seasonal variability in PM2.5 and its carbonaceous species (OC, EC, POC, SOC, and TCM) was observed. Based on the linear association (OC vs. EC) and ratios (OC/EC as well as EC/TC) of species, three significant sources of CAs (vehicular emissions (VE), fossil fuel combustion (FFC), and biomass burning (BB)) were identified

Elemental Variation and Health Risk Assessment of PM2.5 at Delhi during North-East Monsoon and South-West Monsoon

This study elucidates the variation of PM2.5 concentrations in Delhi during the north-east monsoon (NEM) and the south-west monsoon (SWM) period of 2014–2019. The average concentrations of PM2.5 were 113 ± 48 µg/m3 and 50 ± 19 µg/m3 during NEM and SWM, respectively. Further, the elemental composition of PM2.5 was analyzed using wavelength dispersive X-ray Fluorescence (WD-XRF). During NEM, it was observed that the Na, Cl and S dominating over the region, whereas Na, S, Al, dominated during the SWM season. Backward trajectories analysis suggested the long-range transportation of air mass from the Sahara Desert (SD), Arabian Sea (AS), and Bay of Bengal (BOB) for both the seasons (NEM and SWM), thus significantly affecting the loading of mass concentration of PM2.5 at the study site of Delhi. We also evaluated the hazard quotient (HQ) of elements present in PM2.5 over Delhi during this period