Browsing by Author "Santu Ghosh"

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A framework for city-specific air quality health index: a comparative assessment of Delhi and Varanasi, India
(Institute of Physics, 2025) Franciosalgeo George; Pallavi Joshi; Sagnik Dey; R. K. Mall; Santu Ghosh
Air quality index (AQI) is a crucial tool for communicating the health risks of air quality to the public. However, the current AQI in India does not consider the health impacts of exposure to air pollutants, necessitating the development of air quality health index (AQHI). Here, we proposed a framework for developing city-specific AQHI that better reflects local air quality and associated health risks using air pollution and health data from two polluted and densely populated cities in north India—Delhi and Varanasi (Delhi: 2013-2017; Varanasi: 2009-2016). We also constructed a pooled AQHI by combining data from both cities. Using concentrations of ambient fine particulate matter (PM2.5), nitrogen dioxide, and ozone, we applied generalized additive models with a quasi-Poisson link, using daily mortality counts as the outcome, excluding suicide and accidental deaths. A 10 µg m−3 increase in PM2.5 was associated with mortality increases of 0.17% (95% CI: 0.01-0.34) in Varanasi, 0.20% (95% CI: 0.1-0.29) in Delhi, and 0.16% (95% CI: 0.08-0.24) in the pooled model. The city-specific AQHI classified 21.8% of days in Delhi as ‘Satisfactory’ versus 18.2% by the pooled index, while 24.2% of days were ‘Poor’ compared to 30.1% under the pooled index. In Varanasi, 6.8% of days were ‘Good’ under the city-specific AQHI, compared to 9.3% by the pooled index, with 15.7% of days classified as ‘Poor’ versus 19.3% by the pooled index. Our results suggest that a single-pooled AQHI may misrepresent local air quality and associated health risks. Since AQHI values are derived from excess mortality risk estimates, a city-specific AQHI ensures a more accurate reflection of local pollution-related health impacts, supporting targeted public health interventions. We recommend accessibility of health data to enable developing AQHI for non-attainment cities in India and use it to track progress towards cleaner air. © 2025 The Author(s). Published by IOP Publishing Ltd.
Anaemia and iron deficiency in India: a venous blood-based survey of adolescents, adults, and the elderly in eight states
(Springer Nature, 2025) Santu Ghosh; Avula Laxmaiah; Giriraj Ratan Ratan Chandak; Indrapal Ishwarji Meshram; Rajiva Raman; Shantanu Sengupta; Chittaranjan Sakerlal Yajnik; Anura Vishwanath Kurpad; Harshpal Singh Sachdev; Suresh Kumar Yadav; J. Vyshnavi; V. P. Sunu; Krishna Kishore Sukla; G. L. Stephen; Starpala; Kakani Sreeramakrishna; Pooja Singh; S. P.V. Prasad; Monika Pandey; Suraj Singh Nongmaithem; G. Neeraja; D. Narasimhulu; S. K. Kuddeep; Luke Hanna Elizabeth; Rahul Chakraborty; Tapas K. Chakma; Gandham Bulliyya; Dattatray Shivram Bhat; Varanasi Bhaskar; S. Asim
Background: Surveys based on capillary blood show that anaemia is rampant in India, but capillary blood haemoglobin (Hb) may not accurately reflect venous blood Hb concentrations. Further, iron deficiency (ID) is thought to be the main cause of anaemia, there are no venous blood-based surveys to confirm this. Methods: A community-based (urban, slum and rural) cross-sectional, venous blood survey was conducted in eight Indian states to estimate anaemia and ID prevalences from Hb and inflammation-corrected plasma ferritin concentrations in adolescents, adults, and elderly. Results: The prevalence of anaemia was 44%, 41% and 45% in adolescent girls, adult and elderly women respectively, compared to 24%, 21% and 37% in adolescent boys, adult, and elderly men. The overall prevalence varied widely, ranging from 12% in Meghalaya to 70% in Assam. Mild anaemia prevalence was predominant at about half of overall anaemia prevalence. ID-associated anaemia (IDA) prevalence was less than a third of the overall anaemia prevalence, and varied among age and sex groups, approaching 45% only in adolescent girls. IDA prevalence was even lower in the mild anaemia group. Thus, the major proportion of anaemia in all groups was associated with ‘other’ causes. Conclusions: Anaemia prevalence, when measured by venous blood Hb, was substantially lower than earlier capillary blood-based estimates and was predominantly of the mild variety. The prevalence of IDA was also much lower than anticipated; therefore, the aetiological role of ID appears not to be predominant. These results have policy implications for anaemia prevention and correction at the population level. © The Author(s), under exclusive licence to Springer Nature Limited 2025.
Association of aerosols, trace gases and black carbon with mortality in an urban pollution hotspot over central Indo-Gangetic Plain
(Elsevier Ltd, 2021) Nidhi Singh; Alaa Mhawish; Tirthankar Banerjee; Santu Ghosh; R.S. Singh; R.K. Mall
The short term effect of multiple air pollutants e.g. aerosols (black carbon, BC; PM2.5 and PM10) and trace gases (NO2, SO2, and O3) on all-cause mortality was systematically investigated in a typical urban pollution hotspot over central Indo-Gangetic Plain (IGP). To our knowledge, this would be the first report of mortality estimates for exposure to BC aerosols and multiple trace gases over South Asia. Daily all-cause mortality and ambient air quality were analyzed from 2009 to 2016 following a semiparametric quasi-Poisson regression model adjusting mean temperature (Tmean), relative humidity (RH), and long term time trend (Time) as potential confounders. Single pollutant model clearly established the significant impact of BC aerosols (against 10-unit increase in pollutant; 4.95%, 95% CI: 2.16–7.74), NO2 (2.38%, 95% CI: 0.88–3.87%) and PM2.5 exposure (1.06%, 95% CI: 0.45–1.66%) on mortality. The inclusion of co-pollutants in the multi-pollutant model increased the individual mortality risks for BC aerosols (7.3%). Mortality estimates were further stratified considering different effect modifiers viz. sex, age, place of death, and season. Almost in all the cases statistically insignificant differences in effect modification were noted for all the pollutants except PM10. We also explored a distributed lag nonlinear model to estimate the lag effect and all the pollutants showed significant lag up to 3 days while BC showed lag effect up to 5 days. The exposure-response curves for individual air pollutants were mostly linear, while a considerable increase in mortality was noted for an exposure >15 μg m−3 for BC aerosols and >60 μg m−3 for PM2.5. The effect estimates of air pollutants during haze and no-haze days were also defined. During haze days, mortality rose to 6.11% and 3.06% for each 10-unit increase in BC and NO2 exposure, respectively. Significant effect of BC aerosol exposure on human mortality was established which reaffirms its inclusion as a potential health regulator for epidemiological studies. © 2020 Elsevier Ltd
Attributing mortality from temperature extremes: A time series analysis in Varanasi, India
(Elsevier B.V., 2019) Nidhi Singh; Alaa Mhawish; Santu Ghosh; Tirthankar Banerjee; R.K. Mall
Climate extremes are often associated with increased human mortality and such association varies considerably with space and time. We therefore, aimed to systematically investigate the effects of temperature extremes, daily means and diurnal temperature variations (DTV) on mortality in the city of Varanasi, India during 2009–2016. Time series data on daily mortality, air quality (SO 2 , NO 2 , O 3 and PM 10 ) and weather variables were obtained from the routinely collected secondary sources. A semiparametric quasi-Poisson regression model estimated the effects of temperature extremes on daily all-cause mortality adjusting nonlinear confounding effects of time trend, relative humidity and air pollution; stratified by seasons. An effect modification by age, gender and place of death as semi-economic indicator were also explored. Daily mean temperature was strongly associated with excess mortality, both during summer (5.61% with 95% CI: 4.69–6.53% per unit increase in mean temperature) and winter (1.53% with 95% CI: 0.88–2.18% per unit decrease in mean temperature). Daily mortality was found to be increased by 12.02% (with 95% CI: 4.21–19.84%) due to heat wave. The DTV has exhibited downward trend over the years and showed a negative association with all-cause mortality. Significant association of mortality and different metric of temperature extreme along with decreasing trend in DTV clearly indicate the potential impact of climate change on human health in the city of Varanasi. The finding may well be useful to prioritize the government policies to curb the factors that causes the climate change and for developing early warning system. © 2019 Elsevier B.V.
Excess Mortality Risk Due to Heat Stress in Different Climatic Zones of India
(American Chemical Society, 2024) Rohit Kumar Choudhary; Pallavi Joshi; Santu Ghosh; Dilip Ganguly; Kalpana Balakrishnan; Nidhi Singh; Rajesh Kumar Mall; Alok Kumar; Sagnik Dey
India is at a high risk of heat stress-induced health impacts and economic losses owing to its tropical climate, high population density, and inadequate adaptive planning. The health impacts of heat stress across climate zones in India have not been adequately explored. Here, we examine and report the vulnerability to heat stress in India using 42 years (1979-2020) of meteorological data from ERA-5 and developed climate-zone-specific percentile-based human comfort class thresholds. We found that the heat stress is usually 1-4 °C higher on heatwave (HW) days than on nonheatwave (NHW) days. However, the stress on NHW days remains considerable and cannot be neglected. We then showed the association of a newly formulated India heat index (IHI) with daily all-cause mortality in three cities - Delhi (semiarid), Varanasi (humid subtropical), and Chennai (tropical wet and dry), using a semiparametric quasi-Poisson regression model, adjusted for nonlinear confounding effects of time and PM2.5. The all-cause mortality risk was enhanced by 8.1% (95% confidence interval, CI: 6.0-10.3), 5.9% (4.6-7.2), and 8.0% (1.7-14.2) during “sweltering” days in Varanasi, Delhi, and Chennai, respectively, relative to “comfortable” days. Across four age groups, the impact was more severe in Varanasi (ranging from a 3.2 to 7.5% increase in mortality risk for a unit rise in IHI) than in Delhi (2.6-4.2% higher risk) and Chennai (0.9-5.7% higher risk). We observed a 3-6 days lag effect of heat stress on mortality in these cities. Our results reveal heterogeneity in heat stress impact across diverse climate zones in India and call for developing an early warning system keeping in mind these regional variations. © 2023 American Chemical Society