Bhola Ram Gurjar
@iitr.ac.in
Professor, Department of Civil Engineering
Indian Institute of Technology Roorkee, India
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
A. K. Rathi, D. Parmar, R. Ganguly, B. R. Gurjar, and V. Bhadauria
Springer Science and Business Media LLC
Rahul Arya, Sakshi Ahlawat, Lokesh Yadav, Martina Rani, Arnab Mondal, Ritu Jangirh, Garima Kotnala, Nikki Choudhary, Akansha Rai, Ummed Singh Saharan,et al.
Springer Science and Business Media LLC
James M. Cash, Chiara Di Marco, Ben Langford, Mathew R. Heal, Tuhin K. Mandal, Sudhir K. Sharma, Bhola Ram Gurjar, and Eiko Nemitz
Elsevier BV
Anurag Swarnkar and Bhola Ram Gurjar
Elsevier BV
Beth S. Nelson, Daniel J. Bryant, Mohammed S. Alam, Roberto Sommariva, William J. Bloss, Mike J. Newland, Will S. Drysdale, Adam R. Vaughan, W. Joe F. Acton, C. Nicholas Hewitt,et al.
American Chemical Society (ACS)
Divya Singh and Bhola Ram Gurjar
Springer Science and Business Media LLC
Daniel J. Bryant, Beth S. Nelson, Stefan J. Swift, Sri Hapsari Budisulistiorini, Will S. Drysdale, Adam R. Vaughan, Mike J. Newland, James R. Hopkins, James M. Cash, Ben Langford,et al.
Copernicus GmbH
Abstract. Isoprene and monoterpene emissions to the atmosphere are generally dominated by biogenic sources. The oxidation of these compounds can lead to the production of secondary organic aerosol; however the impact of this chemistry in polluted urban settings has been poorly studied. Isoprene and monoterpenes can form secondary organic aerosol (SOA) heterogeneously via anthropogenic–biogenic interactions, resulting in the formation of organosulfate (OS) and nitrooxy-organosulfate (NOS) species. Delhi, India, is one of the most polluted cities in the world, but little is known about the emissions of biogenic volatile organic compounds (VOCs) or the sources of SOA. As part of the DELHI-FLUX project, gas-phase mixing ratios of isoprene and speciated monoterpenes were measured during pre- and post-monsoon measurement campaigns in central Delhi. Nocturnal mixing ratios of the VOCs were substantially higher during the post-monsoon (isoprene: (0.65±0.43) ppbv; limonene: (0.59±0.11) ppbv; α-pinene: (0.13±0.12) ppbv) than the pre-monsoon (isoprene: (0.13±0.18) ppbv; limonene: 0.011±0.025 (ppbv); α-pinene: 0.033±0.009) period. At night, isoprene and monoterpene concentrations correlated strongly with CO during the post-monsoon period. Filter samples of particulate matter less than 2.5 µm in diameter (PM2.5) were collected and the OS and NOS content analysed using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS2). Inorganic sulfate was shown to facilitate the formation of isoprene OS species across both campaigns. Sulfate contained within OS and NOS species was shown to contribute significantly to the sulfate signal measured via AMS. Strong nocturnal enhancements of NOS species were observed across both campaigns. The total concentration of OS and NOS species contributed an average of (2.0±0.9) % and (1.8±1.4) % to the total oxidized organic aerosol and up to a maximum of 4.2 % and 6.6 % across the pre- and post-monsoon periods, respectively. Overall, this study provides the first molecular-level measurements of SOA derived from isoprene and monoterpene in Delhi and demonstrates that both biogenic and anthropogenic sources of these compounds can be important in urban areas.
Aromal Thampan, E. Rajasekar, and B.R. Gurjar
Elsevier BV
Neha Pant, Durga Toshniwal, and Bhola Ram Gurjar
Springer International Publishing
Shailendra Kumar Yadav, Rajeev Kumar Mishra, and Bhola Ram Gurjar
Springer Science and Business Media LLC
Diwali (the festival of lights and crackers) is celebrated grandly, resulting in a significant drop in the city’s air quality. To study the impact of the judicial prohibition in Delhi to improve air quality, a comprehensive and comparative analysis was conducted over two consecutive years, namely 2015–2016 (when no significant regulations on the sale or usage of firecrackers were imposed) and 2017–2018 (when radically different regulations were implemented). Data on PM 10 , PM 2.5 , NO x , and CO were analysed, and their trends and levels with various regulations in place were compared. In 2017, the concentrations of PM 10 , PM 2.5 , NO x , and CO were reduced by 50%, 50%, 71%, and 64%, respectively, compared to 2016. However, in 2018, there was an increase of 32% in PM 10 and PM 2.5 concentrations, as well as a 25% increase in CO concentrations, with the exception of NOx, which decreased to 25% on Diwali day. The data was also examined in conjunction with the entire timeline of the various court rulings and regulations imposed in Delhi. The questionnaire survey study revealed that, despite the legislation in place, ambient air quality continued to deteriorate, necessitating a deeper dive into the policy’s structure and implementation to fine-tune its feasibility and applications. Air pollution-related health effects were recognized by 82% of participants. Despite this, only 13% of people were observed without a mask, and only 12% of people were aware of green crackers as of 2018. To combat this deteriorating situation, the national capital must enact radical and well-thought-out legislation and regulations governing firecrackers, as well as raise public awareness amongst its citizens.
Divya Singh and Bhola Ram Gurjar
Elsevier BV
Salman Khan, Bhola Ram Gurjar, and Veerendra Sahu
Elsevier BV
Shailendra Kumar Yadav, Rajeev Kumar Mishra, and Bhola Ram Gurjar
Elsevier BV
Gareth J. Stewart, Beth S. Nelson, W. Joe F. Acton, Adam R. Vaughan, James R. Hopkins, Siti S.M. Yunus, C. Nicholas Hewitt, Oliver Wild, Eiko Nemitz, Ranu Gadi,et al.
Elsevier BV
Beth S. Nelson, Gareth J. Stewart, Will S. Drysdale, Mike J. Newland, Adam R. Vaughan, Rachel E. Dunmore, Pete M. Edwards, Alastair C. Lewis, Jacqueline F. Hamilton, W. Joe Acton,et al.
Copernicus GmbH
Abstract. The Indian megacity of Delhi suffers from some of the poorest air quality in the world. While ambient NO2 and particulate matter (PM) concentrations have received considerable attention in the city, high ground-level ozone (O3) concentrations are an often overlooked component of pollution. O3 can lead to significant ecosystem damage and agricultural crop losses, and adversely affect human health. During October 2018, concentrations of speciated non-methane hydrocarbon volatile organic compounds (C2–C13), oxygenated volatile organic compounds (o-VOCs), NO, NO2, HONO, CO, SO2, O3, and photolysis rates, were continuously measured at an urban site in Old Delhi. These observations were used to constrain a detailed chemical box model utilising the Master Chemical Mechanism v3.3.1. VOCs and NOx (NO + NO2) were varied in the model to test their impact on local O3 production rates, P(O3), which revealed a VOC-limited chemical regime. When only NOx concentrations were reduced, a significant increase in P(O3) was observed; thus, VOC co-reduction approaches must also be considered in pollution abatement strategies. Of the VOCs examined in this work, mean morning P(O3) rates were most sensitive to monoaromatic compounds, followed by monoterpenes and alkenes, where halving their concentrations in the model led to a 15.6 %, 13.1 %, and 12.9 % reduction in P(O3), respectively. P(O3) was not sensitive to direct changes in aerosol surface area but was very sensitive to changes in photolysis rates, which may be influenced by future changes in PM concentrations. VOC and NOx concentrations were divided into emission source sectors, as described by the Emissions Database for Global Atmospheric Research (EDGAR) v5.0 Global Air Pollutant Emissions and EDGAR v4.3.2_VOC_spec inventories, allowing for the impact of individual emission sources on P(O3) to be investigated. Reducing road transport emissions only, a common strategy in air pollution abatement strategies worldwide, was found to increase P(O3), even when the source was removed in its entirety. Effective reduction in P(O3) was achieved by reducing road transport along with emissions from combustion for manufacturing and process emissions. Modelled P(O3) reduced by ∼ 20 ppb h−1 when these combined sources were halved. This study highlights the importance of reducing VOCs in parallel with NOx and PM in future pollution abatement strategies in Delhi.
Shailendra Kumar Yadav, Sobhan Kumar Kompalli, Bhola Ram Gurjar, and Rajeev Kumar Mishra
Elsevier BV
Ernesto Reyes-Villegas, Upasana Panda, Eoghan Darbyshire, James M. Cash, Rutambhara Joshi, Ben Langford, Chiara F. Di Marco, Neil J. Mullinger, Mohammed S. Alam, Leigh R. Crilley,et al.
Copernicus GmbH
Abstract. Air pollution in urban environments has been shown to have a negative impact on air quality and human health, particularly in megacities. Over recent decades, Delhi, India, has suffered high atmospheric pollution, with significant particulate matter (PM) concentrations as a result of anthropogenic activities. Organic aerosols (OAs) are composed of thousands of different chemical species and are one of the main constituents of submicron particles. However, quantitative knowledge of OA composition, their sources and their processes in urban environments is still limited. This is important particularly in India, as Delhi is a massive, inhomogeneous conurbation, where we would expect the apportionment and concentrations to vary depending on where in Delhi the measurements/source apportionment is performed, indicating the need for multisite measurements. This study presents the first multisite analysis carried out in India over different seasons, with a focus on identifying OA sources. The measurements were taken during 2018 at two sites in Delhi, India. One site was located at the India Meteorological Department, New Delhi (ND). The other site was located at the Indira Gandhi Delhi Technical University for Women, Old Delhi (OD). Non-refractory submicron aerosol (NR-PM1) concentrations (ammonium, nitrate, sulfate, chloride and organic aerosols) of four aerosol mass spectrometers were analysed. Collocated measurements of volatile organic compounds, black carbon, NOx and CO were performed. Positive matrix factorisation (PMF) analysis was performed to separate the organic fraction, identifying a number of conventional factors: hydrocarbon-like OAs (HOAs) related to traffic emissions, biomass burning OAs (BBOAs), cooking OAs (COAs) and secondary OAs (SOAs). A composition-based estimate of PM1 is defined by combining black carbon (BC) and NR-PM1 (C-PM1= BC + NR-PM1). No significant difference was observed in C-PM1 concentrations between sites, OD (142 ± 117 µg m−3) compared to ND (123 ± 71 µg m3), from post-monsoon measurements. A wider variability was observed between seasons, where pre-monsoon and monsoon showed C-PM1 concentrations lower than 60 µg m−3. A seasonal variation in C-PM1 composition was observed; SO42- showed a high contribution over pre-monsoon and monsoon seasons, while NO3- and Cl− had a higher contribution in winter and post-monsoon. The main primary aerosol source was from traffic, which is consistent with the PMF analysis and Aethalometer model analysis. Thus, in order to reduce PM1 concentrations in Delhi through local emission controls, traffic emission control offers the greatest opportunity. PMF–aerosol mass spectrometer (AMS) mass spectra will help to improve future aerosol source apportionment studies. The information generated in this study increases our understanding of PM1 composition and OA sources in Delhi, India. Furthermore, the scientific findings provide significant information to strengthen legislation that aims to improve air quality in India.
Richa Katiyar, B.R. Gurjar, Amit Kumar, and Randhir K. Bharti
Elsevier BV
Rajiv Ganguly, Divyansh Sharma, Prashant Kumar, and B. R. Gurjar
American Society of Civil Engineers (ASCE)
Abstract Vehicular pollution is one of the major sources of air pollution in urban locales that have reportedly elevated concentrations of air pollutants. This study aims to examine the performance...
Rajmal Jat, Bhola Ram Gurjar, and Douglas Lowe
Elsevier BV
Abstract Air quality in India during the winter months is particularly bad, due to the meteorological conditions limiting dispersal of pollutants. However, investigations of this period using regional air quality models have, so far, been limited. Air quality simulations, using the Weather Research and Forecasting with Chemistry (WRF-Chem) model, at a high grid resolution of 12 km × 12 km, have been carried out for the 2015–16 winter period over the Indian subcontinent. Gas and aerosol chemistry are simulated using the CBM-Z and MOSAIC (4-bin) modules. Emissions from the EDGAR-HTAPv2.2 database are used, scaled to the simulation year based on changes in activity data for each Indian state, which increases national emissions of PM2.5, BC, OC, NOx, SO2 and NMVOCs by 2.6, 0.3, 0.5, 6, 13.5 and 3.6 Gg/day, respectively, in winter. Model performance was evaluated with respect to ground-based observations of PM2.5, CO, NO2 and O3 from available monitoring stations in the cities Ahmedabad, Bangalore, Chennai, Delhi, Agra, Lucknow, Patna, Mumbai, Kolkata, and Hyderabad. PM2.5 predictions at most of the monitoring cities fell within the excellent model performance criteria (Mean Fractional Bias range − 0.15 to 0.11). The NO2 concentrations were reproduced well by the model, with a Mean Fractional Bias range of −0.17 to 0.25. CO concentrations were generally underpredicted, but with relatively smaller biases over northern Indian cities. Ozone was reasonably reproduced at Delhi, but modelled day time peaks are much higher than observations in the other cities (~ 42–62%). Patterns of diurnal cycles of pollutants were found to be broadly similar for both observations and WRF-Chem predictions. The 24 h averaged PM2.5 mass loading over most Indian cities and states were found to exceed the Indian National Ambient Air Quality Standard (NAAQS). PM2.5, CO and NO2 mass loadings were highest in northern and eastern India, particularly over the Indo-Gangetic Plain. Overall in this study, wintertime pollution loading in India is reproduced well by WRF-Chem. However, creating diurnal emission cycles based on local activity data, updated national emission inventories for recent years at higher resolution, and extra air quality monitoring stations, especially in rural areas, are needed to increase the accuracy and validation of model predictions, to better inform policy making.
Veerendra Sahu and Bhola Ram Gurjar
Informa UK Limited
The present study aims to assess the air quality status in the central library of Indian Institute of Technology Roorkee, India. Pollutants concentrations (i.e. PM10, PM2.5, PM1 and TVOC) and comfort parameters i.e. CO2, temperature and relative humidity were monitored across all floors of the library. Air quality was found to vary significantly (P < 0.05) among the different floors of the library. The average concentration of PM10, PM2.5 and PM1 was found to be highest at the first floor. On the other hand, the highest concentration of TVOC (51.7 ± 30 ppb) and CO2 (838.4 ± 99 ppm) was observed at the ground floor. Pollutant concentration was higher in the morning hours. The indoor pollutants were found positively correlated with each other except relative humidity. Indoor to outdoor ratio for PM1, TVOC and CO2 was found to be greater than 1, which indicate a substantial contribution from indoor sources. Exceedance of WHO guidelines was observed for the daily average PM2.5 concentration. Abbreviation: IAQ: indoor air quality; ASHRAE: American Society of Heating, Refrigerating, and Air-Conditioning Engineers; WHO: World Health Organization; PM: particulate matter; VOC: volatile organic carbon; CO2: carbon dioxide; TVOC: Total volatile organic compound; RH: relative humidity; HVAC: heating ventilation and air-conditioning; PID: Photo Ionization Detector; PTFE: Polytetrafluoroethylene; NDIR: Non-dispersive infra-red.
Veerendra Sahu and Bhola Ram Gurjar
Elsevier BV
Abstracts The present study aims to assess spatial and seasonal variations of indoor air quality (IAQ) among ten different indoor microenvironments of a technical university in India. Particulate matters (PM10 and PM2.5), total volatile organic compounds (TVOCs), carbon dioxide (CO2), and indoor environmental quality (IEQ) indicators (i.e. temperature, relative humidity, and ventilation) were monitored during monsoon, winter and summer seasons from August 2018 to June 2019. The occupants’ perception about IAQ of studied microenvironments was analysed from 137 valid responses. The IAQ was found varying significantly (P