Indian Megacities Research Articles

Cytokine gene polymorphisms and suicide risk in an Indian ancestral population: A case-control study

Background India currently accounts for a majority of global suicide deaths. Research in European ancestry has established that suicide mortality has a significant genetic component, and suggests that inflammation may play a crucial role in the pathophysiology of suicide. Inflammation is also highly relevant in regions of increased pollution exposure, such as the megacities of India. To address the existing gaps in genetic research on suicide and possible association with inflammatory biomarkers, we examined genetic polymorphism and clinical risk phenotypes in a population-based suicide-death cohort, India. Material and methods Genotyping of IL-1β(rs16944) & (rs1143627), IL-4(rs2070874), IL-6(rs1800795) and IL-10(rs1800896) was done in 234 post-mortem suicide-death cases and 256 post-mortem controls (N = 490) using PCR RFLP method. Results Our analyses identified three significant (p < 0.001) associations of cytokine variants with suicide death, including IL-1β(rs16944), OR = 0.627; IL-4(rs2070874), OR = 0.524; and IL-6(rs1800795), OR = 2.509. Cases were more likely female and were more likely to have a history of psychiatric illness, though rate of psychiatric illness was low in suicide cases(9%). Conclusion Our genetic results are generally consistent with previous research on risk for depression and suicidal behaviour, and both genetic and phenotypic results provide new insights into risk factors that may contribute to suicide in India.

Wastewater surveillance of severe acute respiratory syndrome coronavirus-2 in open drains of two Indian megacities captures evolutionary lineage transitions: a zonation approach.

Wastewater-based environmental surveillance (WBES) has been proven as proxy tool for monitoring nucleic acids of pathogens shed by infected population before clinical outcomes. The poor sewershed network of low to middle-income countries (LMICs) leads to most of the wastewater flow through open drains. We studied the effectiveness of WBES using open drain samples to monitor the emergence of the SARS-CoV-2 variants in 2 megacities of India having dense population through zonation approach. Samples from 28 locations spanned into 5 zones of Pune region, Maharashtra, India, were collected on a weekly basis during October 2021 to July 2022. Out of 1115 total processed samples, 303 (~ 27%) tested positive for SARS-CoV-2. The periodical rise and fall in the percentage positivity of the samples was found to be in sync with the abundance of SARS-CoV-2 RNA and the reported COVID-19 active cases for Pune city. Sequencing of the RNA obtained from wastewater samples confirmed the presence of SARS-CoV-2. Of 337 sequences, lineage identification for 242 samples revealed 265 distinct SARS-CoV-2 variants including 10 highly transmissible ones. Importantly, transition from Delta to Omicron variant could be detected in wastewater samples 2weeks prior to any clinically reported Omicron cases in India. Thus, this study demonstrates the usefulness of open drain samples for real-time monitoring of a viral pathogen's evolutionary dynamics and could be implemented in LMICs.

Understanding the habitat vulnerability of Slums to COVID 19: Case of two megacities of India.

Urban slums are hotspots of infectious diseases like COVID-19 as was seen in the waves of 2020 and 2021. One of the primary reasons why slums are disproportionately affected is their location in inaccessible and uninhabitable zones, crowded and poorly ventilated living spaces, unsanitary conditions and common facilities (water taps, common toilets, etc.). Staying at home during pandemics is hardly an option for slum dwellers as it often means giving up work and even basic necessities. This paper aims to understand the habitat vulnerabilities of slums in the two Indian megacities of Pune and Surat which were the worst hit during both waves. The study is done at the level of wards, which is the smallest administrative boundary, taking the habitat vulnerability (congestion and access to basic services). To identify the explanatory variables which increase the vulnerability of slums to infectious diseases, literature study is done on the triggering factors which affect habitat vulnerability derived from common characteristics and definitions of slum. The aim of the research is to categorize the slums into 3 levels of risk zones and map them subsequently. This study will help in formulating a model to prioritize the allocation of sparse resources in developing countries to tackle the habitat vulnerabilities of the slum dwellers especially during health emergencies of contagious diseases like COVID-19.

Air pollution walk as an impact education tool for air quality sensitization: a pilot from an Indian megacity

Abstract. Air pollution has become a serious matter of concern in the global south, and a significant amount of funding has been used to create awareness of air pollution. The conventional method of sensitization relies on workshops where slide-based presentations, images, plots and graphs are shown to participants. However, sensitization about air quality using such an audio-visual format might not be sufficient to create adequate impact. Here, in this study, we propose a new sensitization technique, the pollution walk, where participants and a subject matter expert will walk through different urban micro-environments with a live air quality monitor. A pilot involving three such pollution walks with 24 participants was conducted in a South Asian megacity, and pre- and post-walk surveys were conducted. The results indicate a greater sense of understanding among the participants, and the multi-disciplinary nature of the air pollution problem has been communicated well. To understand the long-term impact, a survey after 1 year was conducted which clearly indicates high levels of awareness and behavioural changes among the participants.

Evaluating cooling effect of blue-green infrastructure on urban thermal environment in a metropolitan city: Using geospatial and machine learning techniques

Urban blue-green infrastructures (BGIs) have a considerable cooling effect, reducing the urban heat island effect. Therefore, this study aims to evaluate the cooling effects of BGIs and role of the influencing factors on urban thermal environment in Kolkata city, which is one of the largest mega cities of India. An integrated radius and non-linear regression approach was used to determine the maximum distance over which cooling is effective. Further, the relationship between cooling effects of BGIs and influencing factors was analysed using Random Forest based Explainable artificial intelligence model. The result shows that for most of the BGIs, the range of maximum cooling distance varies from 210 to 240 m from the boundary of BGIs. The average PCA value ranges from 6.12 to 16.77 hectares and PCE value ranges from 1.62 to 2.87 depending of BGIs. The results of PCA, PCE and maximum cooling distance indicate that the spatial configurations of BGIs and landscape pattern within and surrounding of BGIs sites strongly influence the cooling effects. The outcomes of this study provide valuable insights for the policymakers and urban planner about the intervention of blue-green infrastructures for the better urban environmental conditions and heat mitigation in mega cities and other urban areas.

Meteorology-driven trends in PM2.5 concentrations and related health burden over India

As a heavily polluted country, India has made great efforts on mitigating severe PM2.5 pollution during last several years. Quantifying meteorological impacts on PM2.5 pollution and related health burden is essential to accurately assess pollution control effects and therefore provides a reference for air quality policy in India. This study identifies meteorological influences on PM2.5 trends and related mortality during 2014–2021 in five Indian megacities (Chennai, Kolkata, Hyderabad, Mumbai, Delhi). Decreasing trends in PM2.5 concentrations are observed in all cities and seasons with the maximum trend of −7.24 μg m−3 yr−1 in Delhi during winter. Meteorology causes PM2.5 decreases in all cities and seasons with meteorology-driven downward trends of −6.51 ∼ −0.36 μg m−3 yr−1. Meteorology dominates PM2.5 decreases in Delhi during summer/monsoon and Chennai/Mumbai/Delhi during winter, where meteorology-driven PM2.5 trends contribute 65% ∼ 105% of observed PM2.5 decreases. Better ventilation condition is identified as the primary meteorological factor for PM2.5 decrease. Anthropogenic emissions almost play positive roles in improving India's PM2.5 air quality, confirming the effectiveness of pollution control measures in India during recent years. Meteorological conditions dominate decreases in PM2.5-related deaths in 25% of cities and seasons. The most significant meteorology-driven PM2.5-related mortality trend of −127.12 deaths yr−1 occurs in Delhi during winter.

Seasonal variation in heavy metal intake and excretion by dairy cattle in an Indian megacity

Milk consumption plays a pivotal role in human nutrition, especially for children, due to its high protein, calcium, and vitamin contents that aid cognitive development. Nonetheless, potential hazards from heavy metal presence in milk, due to environmental exposure and intake through feed, have gained global attention. Given paucity of data we investigated the seasonal variation in the quantitative intake of heavy metals (cadmium: Cd, chromium: Cr, lead: Pb) by dairy cows in the South Indian megacity of Bengaluru, and the resulting heavy metal concentrations in milk and feces. The research involved 39 dairy farms across urban and peri‑urban areas, where 281 feed, 329 milk, and 183 feces samples were collected along with management data during monsoon (July 2020 - August 2020), winter (November 2020 – February 2021) and summer (March 2022 – June 2022) seasons. During the summer season, Cd concentration in lake fodder averaged 1.6 mg/kg DM, which was higher than the 0.6 mg/kg DM during winter and 0.9 mg/kg DM during the monsoon season. The higher concentration resulted in an increased daily Cd intake of 13.7 mg/cow/day. Similarly, Cr and Pb intake were also highest in summer (Cr: 46.3 mg/cow/day, Pb: 11.7 mg/cow/day), whereby for both elements the concentrations were higher in non-lake feed than in lake fodder. With the exception of a few milk samples, Cr and Pb concentrations were below threshold levels and did not compromise milk safety, and Cd levels never raised concerns. Nevertheless, elevated Cr and Pb concentrations (Cr: 9.8–16.9 mg/kg DM, Pb: 4.1–10.6 mg/kg DM) were determined in feces across seasons, potentially endangering the environment and reintroducing these elements into the food chain through manure application on agricultural land. Rather than uniformly discouraging the use of lake fodder in Bengaluru, authorities on the one hand should caution fodder usage in pollution-prone areas, and on the other hand take measures to reduce contamination levels at those sites. Furthermore, it appears necessary to implement more stringent control measures for other types of feedstuffs. Raising farmers' awareness of the problem of heavy metals in the food chain could promote their compliance with regulations without the need for complete feed bans, which are difficult to enforce in a highly contested urban environment.

Strategic interventions for bridging the design-reality gap in property conferment rights: a case study of India’s ambitious initiative

PurposeThis research aims to assess how well the e-governance initiative aligns with its design expectations and on-ground realities for property management to redevelop Delhi, the mega-city of India. Additionally, the study proposes strategic interventions to address any gaps identified, aiming to improve the project’s effectiveness and success.Design/methodology/approachThe research employs a singular exploratory case study methodology to scrutinise the e-governance initiative undertaken by the Government of India to confer property rights. Specifically, the study utilises a qualitative research approach known as design-reality gap (DRG) analysis. The study draws from primary and secondary sources using a mixed-methods data collection strategy. Primary data are gathered through a purposeful and snowball sampling method involving direct engagement with respondents, whilst secondary data are sourced from the project portal.FindingsThe investigation reveals a substantial disparity between the planning and execution phases of e-governance projects. This incongruity predominantly manifests in the domains of process, staffing and skills, as well as objectives and values. The study further finds that strategic collaboration amongst stakeholders and the sustainability of decisions are the most critical factors in ensuring the success of e-governance initiatives and bridging the DRG of e-governance projects.Research limitations/implicationsThis research highlights the complex challenges faced by e-governance projects in technical, human and organisational aspects. The successful implementation and sustainability of these projects require effective strategies to overcome challenges, which management should proactively identify and act on. To improve services, beneficiaries should be encouraged to provide feedback and suggestions, as they play a crucial role in service enhancement. A dynamic feedback loop would be established by creating a two-way interaction between beneficiaries and service providers, leading to iterative service improvement. It is important to note that the study’s findings are more illustrative than conclusive due to the moderate sample size, reflecting its limitations.Originality/valueThe research contributes to the scholarly discourse on e-governance and policy implementation by comprehensively examining the alignment between conceptual design and real-world execution. It also introduces a normalised scale for the DRG framework, mapping its dimensions to deduce specific outcomes. This innovative approach enhances the research’s originality and value, offering insights applicable in both academic and practical domains.

Impact of lockdown emission scenario on fine particulate matters (PM1) and its comparison with PM2.5 within Indian megacities

Impact of lockdown emission scenario on fine particulate matters (PM1) and its comparison with PM2.5 within Indian megacities

Crowded and warmer: Unequal dengue risk at high spatial resolution across a megacity of India

The role of climate factors on transmission of mosquito-borne infections within urban landscapes must be considered in the context of the pronounced spatial heterogeneity of such environments. Socio-demographic and environmental variation challenge control efforts for emergent arboviruses transmitted via the urban mosquito Aedes aegypti. We address at high resolution, the spatial heterogeneity of dengue transmission risk in the megacity of Delhi, India, as a function of both temperature and the carrying-capacity of the human environment for the mosquito. Based on previous results predicting maximum mosquitoes per human for different socio-economic typologies, and on remote sensing temperature data, we produce a map of the reproductive number of dengue at a resolution of 250m by 250m. We focus on dengue risk hotspots during inter-epidemic periods, places where chains of transmission can persist for longer. We assess the resulting high-resolution risk map of dengue with reported cases for three consecutive boreal winters. We find that both temperature and vector carrying-capacity per human co-vary in space because of their respective dependence on population density. The synergistic action of these two factors results in larger variation of dengue’s reproductive number than when considered separately, with poor and dense locations experiencing the warmest conditions and becoming the most likely reservoirs off-season. The location of observed winter cases is accurately predicted for different risk threshold criteria. Results underscore the inequity of risk across a complex urban landscape, whereby individuals in dense poor neighborhoods face the compounded effect of higher temperatures and mosquito carrying capacity. Targeting chains of transmission in inter-epidemic periods at these locations should be a priority of control efforts. A better mapping is needed of the interplay between climate factors that are dominant determinants of the seasonality of vector-borne infections and the socio-economic conditions behind unequal exposure.

UNDERSTANDING THE DYNAMICS OF URBAN HEAT ISLAND AS A FUNCTION OF DEVELOPMENT REGULATIONS

This study is the first-ever attempt to relate the tools of development control like Floor Space Index (FSI/FAR), ground area covered by building footprints (BFs), and proportions/configurations of open areas, with their impact on the surface urban heat island (SUHI) which modulates the air temperatures. In the case of the Indian megacity Mumbai, statistical analysis of the land surface temperatures (LST) and its correlation with the selected development indicators, reveals that for an FSI increase of 1.0 to 1.8 the SUHI is found to be–2.5 °C less and when BFs reduced from 90% to 42% SUHI was also reduced by –2.5 °C. Highrise development with a large plot size is desirable whereas low-rise development with FSI 1.0 on small plot sizes exhibits the highest SUHI. Open spaces without vegetation do not reduce SUHI. The correlation of development regulations with SUHI intensity will help urban planners to make more informed decisions.

Study of secondary organic aerosol formation and aging using ambient air in an oxidation flow reactor during high pollution events over Delhi

Secondary aerosols constitute a significant fraction of atmospheric aerosols, yet our understanding of their formation mechanism and fate is very limited. In this work, the secondary organic aerosol (SOA) formation and aging of ambient air of Delhi are studied using a potential aerosol mass (PAM) reactor, an oxidation flow reactor (OFR), coupled with aerosol chemical speciation monitor (ACSM), proton transfer reaction time of flight mass spectrometer (PTR-ToF-MS), and scanning mobility particle sizer with counter (SMPS + C). The setup mimics atmospheric aging of up to several days with the generation of OH radicals. Variations in primary volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs) as a function of photochemical age were investigated. Primary VOCs such as benzene, toluene, xylene, trimethyl benzene, etc. decrease and OVOCs like formic acid, formaldehyde, acetone, ethanol, etc. increase substantially upon oxidation in OFR. The highest organic aerosol (OA) enhancement was observed for the 4.2 equivalent photochemical days of aging i.e., 1.84 times the ambient concentration, and net OA loss was observed at very high OH exposure, typically after 8.4 days of photochemical aging due to heterogeneous oxidation followed by fragmentation/evaporation. In ambient air, OA enhancement is highest during nighttime due to the high concentrations of precursor VOCs in the atmosphere. SMPS + C results demonstrated substantial new particle formation upon aging and decrement in preexisting aerosol mass. This is the first experimental study conducting an in-situ evaluation of potential SOA mass generated from the ambient aerosols in India.

Differences in enteric methane emissions across four dairy production systems in the urbanizing environment of an Indian megacity

Low- and middle-income countries (LMICs) are rapidly urbanizing, leading to a high demand for high-quality animal products. Production increase is seen as a key to meeting this demand and reducing the global environmental impact of low-yielding dairy production system (DPS) often found in LMICs. Therefore, the present study assesses the relationship between enteric methane emissions and different dairy production strategies, taking DPS in the rural–urban interface of Bengaluru, an Indian megacity, as a case study. Twenty-eight dairy farms, evenly distributed across four DPS, were monitored for 1 year (eight visits at 6-week intervals). Following IPCC 2006 guidelines and a Tier 2 approach, enteric methane emissions from dairy cattle were calculated as carbon dioxide equivalents (CO2 eq). Dairy producers in ExtDPS, an extensive DPS found throughout the rural–urban interface of Bengaluru, fed their dairy cattle a high-quality diet, partly based on organic wastes from markets or neighbors, achieving 9.4 kg energy-corrected milk (ECM) per cow and day. Dairy producers in Semi-ADPS, a semi-intensive and rural DPS, fed an average quality diet and achieved the lowest milk production (7.9 kg ECM cow−1 day−1; p &amp;lt; 0.05). Dairy producers in Semi-BDPS, another semi-intensive and rural DPS, relied on average quality but more abundant feedstuffs and achieved a production of 10.0 kg ECM cow−1 day−1. A similar milk yield (10.1 kg ECM cow−1 day−1) was achieved by IntDPS, an intensive and rural DPS. The intensity of enteric methane emissions was the highest in Semi-BDPS (1.38 kg CO2-eq kg−1 ECM; p &amp;lt; 0.05), lowest in ExtDPS (0.79 kg CO2-eq kg−1 ECM; p &amp;lt; 0.05), and intermediate in semi-ADPS and IntDPS. The results highlight the close relationship between the intensity of enteric methane emissions and the intensification strategies chosen by dairy producers based on locally available resources. They also underline the importance of region- and system-specific environmental assessments of production systems in LMICs.

What Makes the Indian Megacity Chennai’s Air Unhealthy? - A Bottom-up Approach to Understand the Sources of Air Pollutants

What Makes the Indian Megacity Chennai’s Air Unhealthy? - A Bottom-up Approach to Understand the Sources of Air Pollutants

The city in film: Reading Dhobi Ghat and Island City as cinematic representations of Mumbai

Urban spaces harbour the capacity to embody varied social relations that constantly interact to form lived experiences. As the society has gradually transformed from a collection of rural settlements to a largely metropolitan space, urban fiction as a literary genre set in city landscapes has become increasingly popular. In a century dominated by new media technologies, the changing contours of contemporary societies became widely visible in the images and interpretations available through cinema. Cinema as one of the predominant modes of cultural expressions has played a performative role in encapsulating the changing lifestyles, attitudes and landscapes. The city as a mosaic of complexity, diversity and contradictions has consequently become an inseparable part of the world’s largest film industry – Bollywood. The Indian megacity of Mumbai has thus become a site of ‘glocal’ interconnections and polyphonic voices. Not only has the city contributed to the production and dissemination of films, but its increased influence has also allowed it to feature as a ‘character’ in many films. This article seeks to evaluate select cinematic narratives to foreground the living realities of the megacity of Mumbai. While examining the representation of Mumbai in two films released post-2010 – Dhobi Ghat (Mumbai Diaries) and Island City, the article intends to interpret the implicit and explicit meanings in the cinematic language of these films. It seeks to argue that cinematic representations of Mumbai help to characterize ways of perceiving the city as a complex, multi-layered urban text. Rather than visualizing the city as an empty space that simply holds the narrative together, the article aims to show how cities in films become characters themselves, engulfing those of flesh and bone.

Modelling and forecasting of urban flood under changing climate and land use land cover

Abstract Chennai is a rapidly urbanizing Indian mega-city and experiences flooding frequently. Literature state that climate change and land use change have a significant impact on the runoff generated every year, making it essential to study the historical trend and forecast changes in land use land cover (LULC) and climate to model runoff. This study considered Adyar watershed for LULC change detection, climate change analysis, and flood forecasting for 2030 and 2050 based on LULC and runoff from 2005 and 2015. A coupled hydrologic–hydraulic model (HEC-HMS and HEC-RAS) was developed to assess flooding for future LULC and climate scenarios. LULC analysis shows an increase in built-up cover by 6%. Climate analysis shows 74% probability of increase in precipitation intensity between 2015 and 2050 compared to 2015. It was observed that depth of flooding increased by 19.4% in 2030 and 60.4% in 2050 compared to 2015. This study makes a structural proposition for flood mitigation through flood carrier canals on the downstream reach of the river which flows through Chennai. The canals were found to significantly reduce overbanking, providing protection against flooding. This is the best measure for providing the highest flood reduction for the study area.

Long-term trend of PM2.5 over five Indian megacities using a new statistical approach

Long-term trend of PM2.5 over five Indian megacities using a new statistical approach

Urbanization alters the spatiotemporal dynamics of plant-pollinator networks in a tropical megacity.

Urbanization is a major driver of biodiversity change but how it interacts with spatial and temporal gradients to influence the dynamics of plant-pollinator networks is poorly understood, especially in tropical urbanization hotspots. Here, we analysed the drivers of environmental, spatial and temporal turnover of plant-pollinator interactions (interaction β-diversity) along an urbanization gradient in Bengaluru, a South Indian megacity. The compositional turnover of plant-pollinator interactions differed more between seasons and with local urbanization intensity than with spatial distance, suggesting that seasonality and environmental filtering were more important than dispersal limitation for explaining plant-pollinator interaction β-diversity. Furthermore, urbanization amplified the seasonal dynamics of plant-pollinator interactions, with stronger temporal turnover in urban compared to rural sites, driven by greater turnover of native non-crop plant species (not managed by people). Our study demonstrates that environmental, spatial and temporal gradients interact to shape the dynamics of plant-pollinator networks and urbanization can strongly amplify these dynamics.

Affordable and sustainable transportation: Key drivers and policy choices for a megacity in India

The city of Bengaluru is one of the latest entrants to the list of 33 mega cities in the world. The transportation infrastructure of the city is expanding to accommodate the rapidly increasing population. As such, there is a need to reevaluate public transport policies to achieve the Sustainable Development Goal (SDG) target 11.2. In this study, we conducted a socio-economic survey of 1350 households belonging to the low and low-middle income categories in Bengaluru city to understand their travel behaviour and transportation mode choices in the event of changing transport infrastructure dynamics of the city. While two-wheelers are the dominant mode among employed working males in the age group of 18–45 years, buses are preferred for long-distance travel. Metro ridership is low even where metro stations are accessible at the start of the journey because low- and middle-income groups are unable to afford metro services. Additionally, we used Random Forest model to assess the contribution of each explanatory variable in mode choice determination. The results shows that travel cost followed by travel time and travel distance are the most important explanators in determining the mode choice for our sample population. Based on these findings, the authors have created two scenarios to assess the impact of metro fare rationalisation on metro ridership. This study quantifies the co-benefits of the proposed policy changes in terms of economic benefits to the operators and the avoidance of air pollution and CO2 emissions.

Direct and indirect effects of urbanization, pesticides and wild insect pollinators on mango yield

Abstract Expanding cities increasingly encroach fertile farmlands, questioning the viability of maintaining agriculture within and around them. Yet, our knowledge on how urbanization influences pollinator communities and the provision of pollination services to crops is limited, especially for the urbanization hotspots of the Global South. Mango Mangifera indica is one of the most important fruit crops in tropical countries. To analyse the dependency of mango on its main insect pollinators, and the direct and indirect effects of urbanization and insecticides on pollinator abundance and mango yield, we conducted a pollinator exclusion experiment and sampled flower visitors on 16 mango farms spread across rural–urban landscapes in Bengaluru, a South Indian megacity. We found that allowing flowers access to ants and flying visitors (bees, hoverflies, nonsyrphid flies), dramatically increased mango yield by 350%, highlighting the importance of wild insects for mango pollination. We detected a trend between wild bee abundance and the final fruit set, with an increase of 20% when the number of bees increased from 25 to 125. Urbanization did not directly affect pollinator abundance or mango yield. However, the amount of insecticide applications had strong negative effects on wild bee abundance at low and intermediate levels of urbanization, while it had no effect in highly urbanized areas, presumably because of higher availability of flowering resources. Moreover, the amount of insecticides decreased the weight of harvested mango fruits by almost 30%. This may indicate trade‐offs between conventional pest control and enhanced crop yields through pollination by wild insects in rural areas. Synthesis and applications: Our results indicate that mango production can be maintained at a profitable level in urbanized landscapes with insect pollinators more than tripling final yield. However, increasing use of insecticides, besides raising farmers' expenses, can have negative effects on wild insect pollinators and mango yield, especially in rural areas. To safeguard crucial pollination services, it is therefore critical to conserve and promote wild insect pollinators by minimizing the negative effects of insecticide applications in these areas.