@article{madhwal_tripathi_bergin_bhave_foy_reddy_chaudhry_jain_garg_lalwani_2024, title={Evaluation of PM<sub>2.5</sub> spatio-temporal variability and hotspot formation using low-cost sensors across urban-rural landscape in lucknow, India}, volume={319}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2023.120302}, journal={ATMOSPHERIC ENVIRONMENT}, author={Madhwal, Sandeep and Tripathi, Sachchida Nand and Bergin, Michael Howard and Bhave, Prakash and Foy, Benjamin and Reddy, T. V. Ramesh and Chaudhry, Sandeep Kumar and Jain, Vaishali and Garg, Naresh and Lalwani, Paresh}, year={2024}, month={Feb} }
 @article{goetz_giordano_stockwell_bhave_puppala_panday_jayarathne_stone_yokelson_decarlo_2022, title={Aerosol Mass Spectral Profiles from NAMaSTE Field-Sampled South Asian Combustion Sources}, ISSN={["2472-3452"]}, DOI={10.1021/acsearthspacechem.2c00173}, abstractNote={Unit mass resolution mass spectral profiles of nonrefractory submicron aerosol were retrieved from undersampled atmospheric emission sources common to South Asia using a “mini” aerosol mass spectrometer. Emission sources including wood- and dung-fueled cookstoves, agricultural residue burning, garbage burning, engine exhaust, and coal-fired brick kilns were sampled during the 2015 Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) campaign. High-resolution peak fitting estimates of the mass spectra were used to characterize ions found within each source profile and help identify mass spectral signatures unique to aerosol emissions from the investigated source types. The first aerosol mass spectral profiles of dung burning, charcoal burning, garbage burning, and brick kilns are provided in this work. The online aerosol mass spectra show that organics were generally the dominant component of the nonrefractory aerosol. However, inorganic aerosol components including ammonium and chloride were significant in dung- and charcoal-fired cookstove emissions and sulfate compounds were major components of the coal-fired brick kiln emissions. Organic mass spectra from both the charcoal burning and zigzag brick kiln were dominated by nitrogen-containing ions thought to be from the electron ionization of amines and amides contained in the emissions. The mixed garbage burning emissions profiles were dominated by plastic combustion with very low fractions of organic markers associated with biomass burning. The plastic burning emissions were associated with enhanced organic signal at mass-to-charge (m/z) 104 and m/z 166, which could be useful fragment ion indicators for garbage burning in ambient aerosol profiles. Finally, a framework for the identification of emission sources using the unit mass resolution organic mass fractions at m/z 55 (f55), m/z 57 (f57), and m/z 60 (f60) is proposed in this work. Plotting the ratio of f55 to f57 versus f60 is found to be effective for the identification of emissions by the fuel type and even useful in separating emissions of similar source types. Although the sample size was limited, these results give further context to the aerosol and gas-phase emission factors presented in other NAMaSTE works and provide a critical reference for future aerosol composition measurements in South Asia.}, journal={ACS EARTH AND SPACE CHEMISTRY}, author={Goetz, J. Douglas and Giordano, Michael R. and Stockwell, Chelsea E. and Bhave, Prakash V and Puppala, Praveen S. and Panday, Arnico K. and Jayarathne, Thilina and Stone, Elizabeth A. and Yokelson, Robert J. and DeCarlo, Peter F.}, year={2022}, month={Nov} }
 @article{das_bhave_puppala_shakya_maharjan_byanju_2020, title={A model-ready emission inventory for crop residue open burning in the context of Nepal}, volume={266}, ISSN={["1873-6424"]}, DOI={10.1016/j.envpol.2020.115069}, abstractNote={Open burning of crop residue is an important source of air pollution which is poorly characterized in South Asia. Currently, the gridded inventory reported by Global Fire Emissions Database for biomass burning including open burning of crop residue are of coarse resolution (0.25° × 0.25°), and may not be appropriate for a simulation for Nepal. This study develops a comprehensive high resolution (1 km × 1 km) gridded model-ready emissions inventory for Nepal to understand the spatial characteristics of air pollutant emissions from open burning. We estimate the national air pollutant emissions from crop residue burned between the years 2003 and 2017. The best available data on agricultural production, residue consumption patterns, agricultural burning parameters and emission factors were derived from secondary sources. The Monte Carlo method was used to estimate uncertainties. The mass of crop residue burned in 2016/17 was 2908 Gg (61–139%), which was 22% of the dry matter generated that year. By multiplying the burned crop residue mass by emission factors, the air pollutant emissions were estimated as 4140 for CO2 (56–144%), 154 for CO (4–196%), 6.5 for CH4 (7–193%), 1.2 for SO2 (60–140%), 24.5 for PM2.5 (30–170%), 8.6 for OC (38–162%), 2.2 for BC (-1-201%), 7 for NOx (54–146%), 22.5 for NMVOC (8–192%) and 2.7 for NH3 (3–197%) in unit of Gg yr−1. More than 80% of air pollutants were generated during the months of February to May from the open burning of crop residue. The findings of this paper indicate that substantial reduction in open field burning would dramatically improve air quality in both the Terai region and other parts of Nepal and help reduce negative health impacts associated with the open burning of residue such as premature deaths, respiratory disease, and cardiovascular disease.}, journal={ENVIRONMENTAL POLLUTION}, author={Das, Bhupendra and Bhave, Prakash V and Puppala, Siva Praveen and Shakya, Kiran and Maharjan, Bijaya and Byanju, Rejina M.}, year={2020}, month={Nov} }
 @misc{weitekamp_stevens_stewart_bhave_gilmour_2020, title={Health effects from freshly emitted versus oxidatively or photochemically aged air pollutants}, volume={704}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2019.135772}, abstractNote={Epidemiology studies over the past five decades have provided convincing evidence that exposure to air pollution is associated with multiple adverse health outcomes, including increased mortality. Air pollution is a complex mixture of particles, vapors and gases emitted from natural and anthropogenic sources as well as formed through photochemical transformation processes. In metropolitan areas, air pollutants from combustion emissions feature a blend of emitted particles, oxides of carbon, sulfur and nitrogen, volatile organic compounds, and secondary reaction products, such as ozone, nitrogen dioxide, and secondary organic aerosols. Because many of the primary and transformed pollutants track together, their relative contributions to health outcomes are difficult to disentangle. Aside from the criteria pollutants ozone and nitrogen dioxide and some of the simpler aldehydes (e.g. formaldehyde and acrolein), other products from photochemical processes are a particularly vexing class of chemicals to investigate since they comprise a dynamic ill-defined complex mixture in both particulate and gas phases. The purpose of this review was to describe and compare health effects of freshly emitted versus oxidatively or photochemically aged air pollutants. In some cases, (e.g. single volatile organic compounds) photochemical transformation resulted in marked enhancements in toxicity through formation of both known and unidentified reaction products, while in other examples (e.g. aging of automobile emissions) the potentiation of effect was variable. The variation in experimental design, aging system employed, concentration and type of starting agent, and toxicity endpoints make comparisons between different studies exceedingly difficult. A more systematic approach with a greater emphasis on higher throughput screening and computational toxicology is needed to fully answer under what conditions oxidatively- or photochemically-transformed pollutants elicit greater health effects than primary emissions.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Weitekamp, Chelsea A. and Stevens, Tina and Stewart, Michael J. and Bhave, Prakash and Gilmour, M. Ian}, year={2020}, month={Feb} }
 @article{mool_bhave_khanal_byanju_adhikari_das_praveen_2020, title={Traffic Condition and Emission Factor from Diesel Vehicles within the Kathmandu Valley}, volume={20}, ISSN={["2071-1409"]}, DOI={10.4209/aaqr.2019.03.0159}, abstractNote={ABSTRACT
Past research on air quality within the Kathmandu Valley indicates that diesel vehicles make a substantial contribution to the ambient pollution. Hence, it’s important to identify cost-effective measures for reducing their emissions. As a first step, roadside observations of diesel vehicles were recorded between February and April 2017 at six locations: two on the ring road (RR), two inside the RR, and two on major arterial highways outside the RR. Out of all diesel vehicles observed (n = 12,039), 35% were emitting a visible plume of black smoke and hereafter are referred to as “superemitters”. Of the 4,248 superemitters, 45% were buses of varying sizes, 34% were large trucks, and 19% were small pickups. Superemitters made up the largest fraction of diesel vehicle traffic on the RR (43%–46%) but were also abundant inside the RR (27%–29%), where human population and pollutant exposure is greatest. Upon developing a comprehensive understanding of the superemitting vehicle types and ownership, maintenance patterns and servicing costs were studied through a survey of vehicle owners, vehicle drivers, and local maintenance centers. The costs of general servicing ranged between USD 16 for tractors and USD 203 for construction vehicles depending on the size of the vehicle. Lastly, the effect of general servicing on emissions while idling was explored for a small sample of superemitters (n = 4). PM2.5 emissions reduced from 10.90 g L–1 to 3.76 g L–1 and BC emissions reduced from 0.847 g L–1 to 0.596 g L–1 after servicing. Taken together, results from this roadside surveillance study and exploratory emission-measurement campaign provide preliminary evidence that a policy of mandatory, routine maintenance of a targeted subset of the diesel fleet can systematically reduce emissions and improve air quality in the Kathmandu Valley and other cities around the world that are facing similar problems.}, number={3}, journal={AEROSOL AND AIR QUALITY RESEARCH}, author={Mool, Enna and Bhave, Prakash V and Khanal, Nita and Byanju, Rejina M. and Adhikari, Sagar and Das, Bhupendra and Praveen, Siva P.}, year={2020}, month={Mar}, pages={395–409} }
 @article{goetz_giordano_stockwell_christian_maharjan_adhikari_bhave_praveen_panday_jayarathne_et al._2018, title={Speciated online PM1 from South Asian combustion sources - Part 1: Fuel-based emission factors and size distributions}, volume={18}, ISSN={["1680-7324"]}, DOI={10.5194/acp-18-14653-2018}, abstractNote={Abstract. Combustion of biomass, garbage, and fossil fuels in South Asia has led to poor air quality in the region and has uncertain climate forcing impacts. Online measurements of submicron aerosol (PM1) emissions were conducted as part of the Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) to investigate and report emission factors (EFs) and vacuum aerodynamic diameter (dva) size distributions from prevalent but poorly characterized combustion sources. The online aerosol instrumentation included a “mini” aerosol mass spectrometer (mAMS) and a dual-spot eight-channel aethalometer (AE33). The mAMS measured non-refractory PM1 mass, composition, and size. The AE33-measured black carbon (BC) mass and estimated light absorption at 370 nm due to organic aerosol or brown carbon. Complementary gas-phase measurements of carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) were collected using a Picarro Inc. cavity ring-down spectrometer (CRDS) to calculate fuel-based EFs using the carbon mass balance approach. The investigated emission sources include open garbage burning, diesel-powered irrigation pumps, idling motorcycles, traditional cookstoves fueled with dung and wood, agricultural residue fires, and coal-fired brick-making kilns, all of which were tested in the field. Open-garbage-burning emissions, which included mixed refuse and segregated plastics, were found to have some of the largest PM1 EFs (3.77–19.8 g kg−1) and the highest variability of the investigated emission sources. Non-refractory organic aerosol (OA) size distributions measured by the mAMS from garbage-burning emissions were observed to have lognormal mode dva values ranging from 145 to 380 nm. Particle-phase hydrogen chloride (HCl) was observed from open garbage burning and was attributed to the burning of chlorinated plastics. Emissions from two diesel-powered irrigation pumps with different operational ages were tested during NAMaSTE. Organic aerosol and BC were the primary components of the emissions and the OA size distributions were centered at ∼80 nm dva. The older pump was observed to have significantly larger EFOA than the newer pump (5.18 g kg−1 compared to 0.45 g kg−1) and similar EFBC. Emissions from two distinct types of coal-fired brick-making kilns were investigated. The less advanced, intermittently fired clamp kiln was observed to have relatively large EFs of inorganic aerosol, including sulfate (0.48 g kg−1) and ammonium (0.17 g kg−1), compared to the other investigated emission sources. The clamp kiln was also observed to have the largest absorption Ångström exponent (AAE = 4) and organic carbon (OC) to BC ratio (OC : BC = 52). The continuously fired zigzag kiln was observed to have the largest fraction of sulfate emissions with an EFSO4 of 0.96 g kg−1. Non-refractory aerosol size distributions for the brick kilns were centered at ∼400 nm dva. The biomass burning samples were all observed to have significant fractions of OA and non-refractory chloride; based on the size distribution results, the chloride was mostly externally mixed from the OA. The dung-fueled traditional cookstoves were observed to emit ammonium, suggesting that the chloride emissions were partially neutralized. In addition to reporting EFs and size distributions, aerosol optical properties and mass ratios of OC to BC were investigated to make comparisons with other NAMaSTE results (i.e., online photoacoustic extinctiometer (PAX) and off-line filter based) and the existing literature. This work provides critical field measurements of aerosol emissions from important yet under-characterized combustion sources common to South Asia and the developing world.}, number={19}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Goetz, J. Douglas and Giordano, Michael R. and Stockwell, Chelsea E. and Christian, Ted J. and Maharjan, Rashmi and Adhikari, Sagar and Bhave, Prakash V and Praveen, Puppala S. and Panday, Arnico K. and Jayarathne, Thilina and et al.}, year={2018}, month={Oct}, pages={14653–14679} }