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Urban air pollution and exposure-related health impacts are being noticed and discussed very intensely in India. On the other hand, source-specific control is the primary focus for policymakers; however, diverse and complex sources make it difficult to immediately see the action and consequent impacts on better air quality. Many cities across the world have witnessed high air pollution levels at traffic junctions, more so in all Indian cities. Site-specific air pollution reduction can be a promising solution for managing the pollution level at highly polluted locations. CSIR-National Environmental Engineering Research Institute, India, has designed and developed Wind Augmentation and purifYing Unit (WAYU) to remove particulate and gaseous pollutants from urban hot spots such as traffic locations. In the present study, the authors attempted to evaluate the performance of two different designs of WAYU for the removal of particulate matters from polluted air at different traffic locations in Delhi City, the national capital territory of India. The performance analyses show that the current design of WAYU removes PM10 and PM2.5 concentrations in the range of 34–49% and 19–25%, respectively from the inlet air. The total PM collected from all WAYU devices was 34.19 kg from 120,557 operating hours' at all the sampling sites. The PM removal rate depends on the size-segregated particulate matter pollution load in the ambient air. [ABSTRACT FROM AUTHOR]

Delhi metropolitan area suffers from extreme haze during the post‐monsoon and winter season, impacting climate, public health, and economy. We used a high‐resolution time‐of‐flight aerosol mass spectrometer (HR‐ToF‐AMS) and aethalometer at two urban locations in Delhi to capture non‐refractory PM2.5 (NR‐PM2.5) and black carbon (BC) during the post‐monsoon and winter season of 2019–2020. Four haze periods with high composition based‐PM2.5 (C‐PM2.5 = NR‐PM2.5 + BC) concentration and distinct chemical composition were identified, during all of which organics dominated but with varying contribution (∼[50%–70%] of C‐PM2.5). Biomass burning organic aerosol (BBOA) was dominant in all periods (∼[31%–45%] of OA), but the majority of it was highly aged ∼(45%–50%) with high O/C (0.71 and 0.46 at the two sites), formed most likely through rapid dark oxidation of freshly emitted and partially oxidized BBOA. High polycyclic aromatic hydrocarbons (PAH) signals in the fresh BBOA mass spectra suggest incomplete combustion activities such as open biomass burning emissions as major source. During an agricultural burning event in north‐western India, we estimated that ∼(44%–53%) of total C‐PM2.5 (combined contribution of aged BBOA and oxygenated OA) measured in Delhi was influenced by long‐range transported biomass burning emissions. During winter, secondary inorganics constituted a significant fraction apart from organics ∼(48%–55%), mainly in the form of ammonium nitrate (NH4NO3; up to ∼[19%–25%] of C‐PM2.5) and ammonium sulfate (NH4SO4; up to ∼[27%–38%]). Enhanced formation of NH4NO3 and related‐secondary organic aerosol (SOA) were linked to nighttime oxidation of BBOA, while NH4SO4 and related‐SOA were linked to heterogeneous aqueous phase oxidation under high RH conditions (>90%). Plain Language Summary: During post‐monsoon and winter seasons, Delhi experiences high concentration of fine particles leading to haze events. To design targeted mitigation policies, an understanding of key factors responsible for haze events is needed. We used an advanced suite of instrumentation to capture temporal trends of real‐time particle chemical composition at two urban locations in Delhi. Using advanced receptor modelling and molecular level source signatures, the open burning of biomass material was estimated to be the largest contributor to haze events during post‐monsoon and winter haze events. The post‐monsoon haze pollution was largely affected by the aged biomass burning particles likely from the long‐range transport of agricultural residue burning emissions in the upwind states of Delhi. Winter haze episodes were also highly affected by biomass burning emissions, likely from the local burning of wood, coal and/or roadside trash for heating and/or cooking purposes. However, the winter haze particles contained significant aged inorganic material including ammonium nitrate, ammonium sulfate and ammonium chloride aerosol apart from aged organics. This study also suggests that the nighttime aging of biomass burning emissions contributed in the rapid formation of aged organic and inorganic particles, causing haze events. Key Points: Four haze periods with distinct PM2.5 chemical composition were identified during post‐monsoon and winter season in DelhiBiomass burning organic aerosol was dominant in all haze periods with the majority of it present in highly aged formOpen biomass burning emissions undergo rapid nighttime oxidation resulting in high yields of secondary organic and inorganics [ABSTRACT FROM AUTHOR]

The paper presents an emission inventory for Cochin, which is a highly industrialized area situated in the southern part of India. A proper emission inventory is very important for planning pollution control programmes, particularly in coastal sites like Cochin, where environmental situations are of growing concern owing to their typical meteorological conditions. In a systematic way the sources are broadly classified as point, line and area sources. The data on emissions from industries, fuel consumption for vehicular and domestic activities along with the respective emission factors are used for estimating the emissions. The study reveals that industrial sources are mainly responsible for emissions of particulate matter, oxides of sulphur and ammonia in the region. Automobiles are the prime sources of hydrocarbons, oxides of nitrogen and carbon monoxide emitting 95%, 77% and 70% respectively of their total emissions, while the contribution from domestic sources is not very significant. [ABSTRACT FROM AUTHOR]