Kansara, Nikunj Kumar, Anurag Timothy, Rijesh Unnithan, and Manas Chatterjee. Unraveling high altitude-induced thromboembolic disorders: polycythemia or complex mechanisms?. 00:00-00, 2024. Thromboembolic disorders (TEDs) occurring at high altitudes due to exposure to hypoxic environments pose a significant challenge for clinicians in high-altitude area. Hypobaric hypoxia often leads to acquired erythrocytosis, which is believed to increase the incidence of thrombosis. This study aims to examine the relationship between thromboembolic events and erythrocytosis. A prospective study was conducted, including all the patients admitted to Siachen hospital for TEDs from January 01, 2022, to December 31, 2022. Data on height, duration of the stay, hemoglobin (Hb), and packed cell volume levels at the time of admission were recorded. A total of 35 cases were enrolled during the study period. The average age of the patients was 29.10 years (standard deviation: 6.06). The mean deployment height was 17,300 ft, with a range of 12,000 ft-21,600 ft. The average duration of stay was 73 days, ranging from 7 to 162 days. The mean Hb level was 18 g/dl (SD: 2.64), with a range of 12.4 g/dl-22.4 g/dl. Twenty-five cases of thrombotic events (71.4%) occurred with normal Hb levels (<17.5 mg/dl), compared with 10 cases (28.6%) with Hb levels >17.5 mg/dl. Prolonged stays at high altitudes and exposure to hypobaric hypoxia are major stressors. The study suggests that it is not elevated Hb levels, but rather the body's lack of an appropriate physiological response, that contributes to the development of thromboembolic events.

Cornwell, William, Aaron L Baggish, Christoph Dehnert, Benjamin D Levine, and Andrew M Luks. Clinical Conundrum: Climbing at the Extremes of High Elevation with Nonischemic Cardiomyopathy. 00:00-00, 2024.

Häfliger, Alina, Aline Buergin, Laura C. Mayer, Maamed Mademilov, Mona Lichtblau, Talantbek Sooronbaev, Silvia Ulrich, Konrad E. Bloch, and Michael Furian. Sex-specific difference in health-related altitude-effects and their prevention by acetazolamide. Data from a randomized controlled trial. 00:00-00, 2024. Women are underrepresented in studies on acute mountain sickness (AMS), altitude-induced sleep-disordered breathing and preventive acetazolamide use. We analyzed sex-specific altitude-effects in participants of a randomized, placebo-controlled, double-blind trial in healthy lowlanders >40 years. Participants took 375 mg/day acetazolamide or placebo starting 24 hours before ascent to and while staying 2 days at 3,100 m. Main outcomes of this analysis were sex-specific incidence of AMS (Lake Louise score ≥3), nocturnal pulse oximetry (SpO) and apnea-hypopnea index (AHI) at 3,100 m. With placebo, 30 of 119 (25%) women and 4 of 51 (8%) men developed AMS ( = 0.009 between sexes) at 3,100 m. Among women assigned to placebo, SpO (mean ± SE 84 ± 0%) and AHI (16.9 ± 1.3/h) in night 1 at 3,100 m were lower compared to men (SpO 86 ± 0%; AHI 28.3 ± 1.9/h), despite similar baseline values at 760 m. Mean between-sex difference in altitude-effects (women-men) in SpO was -1.4% (95% CI, -2.4 to -0.3%); AHI -10.7/h (95% CI, -15.7 to -5.7/h). The impact of acetazolamide on AMS was not significant for either sex but acetazolamide improved AHI in men (difference men-women, -9.8/h [95% CI, -16.8 to -2.7/h]). This study suggests sex-specific differences in altitude-induced hypoxemia, periodic breathing, AMS incidence, and in the response to preventive acetazolamide treatment.

Ri-Li Ge. Medical problems of chronic hypoxia in highlanders living on the tibetan plateau. 00:00-00, 2024.-Health issues at high altitudes arise due to the lower atmospheric pressure and subsequent reduction in the partial pressure of oxygen in ambient air. While much research has been published on health problems of lowlanders who move to high altitudes, less is known about the medical challenges faced by long-term and permanent high-altitude residents, especially in the Qinghai-Tibetan plateau. In this review, we briefly summarized the chronic hypoxia-related health issues in highlanders, focusing on the specific population of the Qinghai-Tibetan plateau. It deals with important health problems for highlanders, including the main disease categories, from chronic mountain sicknesses and pulmonary hypertension (PH) to kidney, neurocognitive impairments, perinatal problems, and congenital heart defect. However, the most hallmark of disorders is excessive erythrocytosis associated with specific symptoms and signs, and high-altitude heart disease is characterized by excessive PH, right ventricular hypertrophy, and right heart failure. We also provide information on potential treatment strategies, including some traditional Tibetan medical practices and also a combination of Western medicine and traditional Chinese medicine to prevent and treat these conditions effectively. This mini-review is heavily based on a couple of decades of research carried out by Chinese high-altitude medical research groups at the Qinghai-Tibetan Plateau. We believe that this review will provide valuable perspective to researchers whose study interest and base lie in high altitude.

Guo, Yan, Chao Yu, Zhongsheng Lu, Menglan Zhang, Qiang Zhang, and Xiao Liu. Zinc homeostasis plays important roles in hypoxia tolerance: A study conducted clinically and . 00:00-00, 2024. High-altitude environments pose significant challenges to human physiology due to reduced oxygen availability, often resulting in altitude-related illnesses such as high-altitude cerebral edema (HACE). This study focuses on understanding the role of zinc homeostasis in enhancing hypoxia tolerance, which may be pivotal in mitigating the adverse effects of such illnesses. The study involved healthy individuals from high-altitude (4,500-5,000 m) and low-altitude areas (0-200 m), as well as patients with HACE. Blood samples were collected and analyzed. Additionally, a hypoxic model was developed using human brain microvascular endothelial cells (HBMECs), and zinc intervention was implemented. In the blood samples of patients with HACE and those of healthy individuals, there were over 4,000 differentially expressed genes (DEGs), with more than 300 of them linked to zinc. Among these zinc-associated genes, only carbonic anhydrase I (CA1) exhibited a substantial upregulation in expression, while the expression of others was notably downregulated. Compared with the high-altitude group, hemoglobin (Hb) (14.7 vs. 19.5 g/dl) and plasma zinc (37.0 vs. 94.0 mmol/dl) were lower in HACE, while CA1 (55.4 vs. 8.6 g/l) was elevated ( < 0.01). studies confirmed that exposure to hypoxia (O 8%-8.5%, 24 hours) inhibited HBMECs proliferation and migration, increased apoptosis and necrosis, and led to abnormal expression of CA1 and various zinc transport proteins. However, zinc intervention (6 μM, 24 hours) significantly mitigated these adverse effects and improved the cell's ability to tolerate hypoxia. Zinc homeostasis was crucial for hypoxia tolerance. Proper zinc supplementation could potentially alleviate symptoms associated with hypoxia intolerance, such as altitude sickness, but further confirmation was needed.

Many Andean highlanders exposed to chronic hypoxemia are susceptible to excessive erythrocytosis (EE) and chronic mountain sickness (CMS). Nocturnal hypoxemia is more marked than diurnal hypoxemia and includes sustained and intermittent components. The potential for cognitive impairments related to nocturnal hypoxemia in this population has not been extensively studied, but improved understanding may provide opportunities for the prevention of long-term effects of EE and CMS. To examine this relationship, 48 participants residing permanently at 4,340 m completed an overnight sleep study and a battery of cognitive function tests that examined a broad range of cognitive domains. Greater nocturnal hypoxemia was associated with longer reaction times on Balloon Analogue Risk Task (BART) ( < 0.01) and Emotion Recognition Test (ERT) ( < 0.01). Longer completion times of Trail Making Task were also associated with increased nocturnal hypoxemia ( = 0.03). Increased hematocrit was similarly associated with longer reaction times on the ERT ( = 0.01) and the BART ( = 0.01). Overall, our results showed that increased nocturnal hypoxemia and higher hematocrit were associated with impairments in cognitive performance in individuals residing permanently at high altitude.

Ren, Hong, Xi-Yue Yang, Rui Su, HaiLin Ma, and Hao Li. Temporal Effects of Hypoxia Exposure at High Altitudes on Compensatory Brain Function: Evidence from Functional Connectivity of Resting-State EEG Brain Networks. 00:00-00, 2024. The aim of this study was to investigate the effects of prolonged exposure to hypobaric hypoxia at high altitude on changes in brain function measured by electroencephalography (EEG), focusing specifically on the resting-state brain network functional connectivity and compensatory adaptations in brain function among individuals with varying durations of high altitude residency. In study I, 64 participants were divided into high-altitude group (HG) and low-altitude group (LG). Ninety-six long-term migrants residing at an altitude of 3,650 m were recruited for studyII and categorized into three groups based on their duration of stay at high altitude: group A (1-2 years), group B (8-10 years), and group C (18-20 years). Resting-state EEG data were collected from each participant, and functional connectivity analysis was conducted using Phase Locking Value. Study I showed that participants with HG had stronger functional connectivity in the occipital lobe than those with LG ( < 0.05). The study II findings indicate that there were significant differences in functional connectivity strength among the frontal and occipital lobes in groups A, B, and C across the α, β, δ, and θ frequency bands. Specifically, the functional connectivity strength of the frontal lobe was significantly higher in group A compared with group B, and in group B compared with group C ( < 0.05). Additionally, the functional connectivity of the occipital lobe was significantly higher in group C compared with group B, and in group B compared with group A ( < 0.05). The consistent results of the whole frequency band suggest that the individual's occipital lobe function is enhanced to compensate for the damage of frontal lobe function, so as to better adapt to the extreme environment at high altitude.

Stauffer, Emeric, François Caton, Raphael Marlu, Aurélien Pichon, Landry Seyve, Michael Furian, Aymeric Paillisser, Florence Berquet, Jeremy De Abreu, Blandine Deschamps, Benoit Polack, Philippe Connes, Paul Robach, Stéphane Doutreleau, Julien V Brugniaux, Samuel Verges, and Benoit Champigneulle.Acclimatized lowlanders exhibit a hypocoagulable profile after a passive ascent at high altitude. 00:00-00, 2024. Discordant results have been previously reported regarding the impact of high-altitude (HA) exposure on coagulation. We aimed to investigate changes in coagulation parameters in lowlanders exposed to HA for 14 days using a combination of dynamic coagulation assays and conventional tests. We assessed coagulation in 10 lowlanders using whole-blood rotational thromboelastometry (ROTEM), thrombin generation assay (TGA) on poor-platelet plasma, and conventional coagulation tests. Tests were performed at low altitude (LA, 210 m) and at the end of a 14-day sojourn at HA, including passive ascents to 3,800 m for 6 days and then to 5,100 m for 8 days. Conventional tests revealed significant changes in coagulation factors and inhibitors after HA exposure, although these changes remained within normal ranges. ROTEM assays demonstrated a delayed clot initiation in EXTEM/FIBTEM, without any alteration in clot firmness, in HA versus LA ( < 0.01). TGA changes showed an increase in time to peak ( < 0.01), a decrease in endogenous thrombin potential ( < 0.05), and a decrease in thrombin peak ( < 0.001). We found no evidence of hypercoagulability in lowlanders after a 14-day sojourn at HA. In contrast, dynamic coagulation assays (ROTEM and TGA) revealed a hypocoagulable pattern.

Horiuchi Masahiro and Samuel J. Oliver. Post-exercise hypotension after exercising in hypoxia with and without tart cherry supplementation. 00:00-00, 2024. This study investigated the effects of hypoxic exercise with and without tart cherry (TC) supplementation on post-exercise hypotension (PEH). In a randomized order, 12 healthy young adults (9 men and 3 women) completed cycle exercise to exhaustion (1) in normoxia without any supplementation (Norm), (2) in hypoxia (13% O) with placebo (Hypo), and (3) in hypoxia with TC supplementation (Hypo + TC). Supplements were supplied for 5 days pre-trial (TC was 200 mg anthocyanin per day for 4 days and 100 mg on day 5). Cycle exercise total energy expenditure was greater in Norm than Hypo and Hypo + TC ( < 0.001) with no difference between Hypo and Hypo + TC ( = 0.41). Mean arterial pressure (MAP) decreased during recovery in all trials (main effect of time, < 0.001), with no difference in PEH between the trials ( > 0.05, change [Δ] in MAP from pre-exercise at 60 minutes recovery, mean difference, Norm Δ-4.4 mmHg, Hypo Δ-6.1 mmHg, and Hypo + TC Δ-5.2 mmHg). Cardiac baroreflex sensitivity decreased during recovery in all trials ( < 0.001) and was lower in Hypo than Norm and Hypo + TC (main effect of trial, = 0.02). PEH was not increased after exercise in hypoxia, with or without TC supplementation, compared with exercise in normoxia.

Su, Ping, Masako Taniike, Yuko Ohno, and Ikuko Mohri. The effects of high altitude on children's sleep: A community-based study on preschoolers in the Tibetan Plateau. 00:00-00, 2024. It has been reported that high altitude affects breathing during sleep in children. To evaluate the symptoms suspected sleep-disordered breathing (SDB) and sleep quality of preschool children living in high altitude of 2,261-3,800 m above sea level (masl) in the Tibetan Plateau, we conducted the community-based survey using a questionnaire. Sleep problems were assessed in 3,113 children aged 3-6 years in Qinghai province using the Chinese version of the Japanese Sleep Questionnaire for Preschoolers (JSQ-P-C), focusing on obstructive sleep apnea (OSA) and OSA-related symptoms. The effect of altitude on these scores was analyzed. The subscale scores of OSA, morning symptoms, and daytime excessive sleepiness in the JSQ-P-C were higher in children living in areas above 3,000 masl than in those living below 3,000 masl and in Japanese children. Altitude, but not family income or maternal education level, significantly affected the scores of OSA, morning symptoms, and daytime excessive sleepiness. Living at altitudes higher than 3,000 masl may adversely affect children's sleep quality.

We aimed to determine changes in cognitive function resulting from chronic hypobaric hypoxia through proteomic analysis of hippocampal tissue. We screened cognition-related proteins to provide ideas and directions that could help prevent and treat hypoxia-associated cognitive impairment. We analyzed hippocampal tissues from mice exposed to high altitudes and control mice using 4 D label-free quantitative proteomics. The data were analyzed by protein quantitative analysis, functional annotation, differential protein screening, clustering analyses, and functional classification and enrichment. Differential protein expression was investigated using targeted quantitative omics based on parallel response monitoring. We identified and quantified 20 target proteins in 12 samples, of which 18 were significant validated proteins that were or might be related to cognitive functions. Signaling pathways that were significantly enriched in differentially expressed proteins were pyrimidine metabolism, 5'-Adenosine Triphosphate-activated protein kinase signaling, phospholipase D signaling, purine metabolism, inflammatory mediator regulation of transient receptor potential channels, hedgehog signaling pathways, dilated cardiomyopathy, platelet activation, insulin resistance, mRNA surveillance pathways, drug metabolism-other enzymes, and drug metabolism-cytochrome P450. Chronic hypoxia alters protein expression in murine hippocampal tissues. Eighteen differentially expressed cognition-related proteins might be related to cognitive impairment in mice exposed to chronic high-altitude hypoxia.

Lankford, Harvey V, Hannah Kimberley. Supplemental Oxygen on the Annie Smith Peck Expedition of 1903 to 6,367 m (20,892 ft) Mount Sorata (Illampu). 00:00-00, 2024. The 1903 expedition to 6,367 m (20,892 ft) Mount Sorata (Illampu) in Bolivia that was conceived, organized, and led by American mountaineer Annie Smith Peck appears to have been the first to take a supplemental oxygen apparatus to a great mountain. The expedition did not have heavy cylinders of compressed oxygen or closed-circuit rebreathers with chemically generated oxygen but took an apparatus to produce oxygen on the mountain apparently by a 19th century heated chlorate chemical method. Oxygen was to be manufactured in camp, stored in rubber bags, and used with an open-circuit breathing set while climbing. The equipment was taken, but once in Bolivia, a late change in plans resulted in a summit attempt on 6,427 m (21,086 ft) Ancohuma rather than Illampu on the twin-peaked Sorata massif. The summit attempt ended prematurely at 4,700 m (15,350 ft), and the oxygen system was not used. The present paper reviews some of the supplemental oxygen options that were available in 1903 and examines the Sorata expedition, a little-known part of the early history of mountaineering oxygen use.

There is interest among technical, expedition, commercial, and military divers in expanding diving operations to high altitude. However, altitude diving presents unique challenges including acclimatization, increased decompression sickness (DCS) risk, and logistical and equipment considerations. Divers must plan altitude acclimatization strategies conservatively to reduce risk of acute mountain sickness and dehydration before diving. Several methods of augmenting sea level diving tables to be used at altitude have been theorized and tested both in simulated dives and high-altitude expeditions. With proper acclimatization, augmentation of standard diving tables, equipment, and safety planning, diving at high altitude may be performed in many contexts safely while minimizing risk of DCS or injury.

Sharma, Narendra Kumar, Mansi Srivastava, Tikam Chand Dakal, Vipin Ranga, and Pawan Kumar Maurya. Acute hypobaric hypoxia (HH) causes alterations in acetylcholine-mediated signaling through varying expression of muscarinic receptors in the PFC and cerebellum of rats' brain. 00:00-00, 2024. Muscarinic receptor (CHRM) proteins are G-protein-associated acetylcholine receptors found in neuronal membranes. Five major subtypes, CHRM1-CHRM5, modulate acetylcholine in central nervous system signaling cascades. CHRM1, CHRM3, and CHRM5 are linked to Gαq/Gα11 proteins, whereas CHRM2 and CHRM4 are linked to Gαi/Gαo proteins. Limited research has been conducted to explore the impact of HH on CHRM gene expressions. It is caused by low oxygen availability at high altitudes, which impairs neurotransmission, cognitive performance, and physiological functions. Previous studies have shown that exposure to hypoxia leads to a reduction in CHRM receptors, which in turn causes alteration in signal transduction, physiological responses, cognitive deficits, and mood alterations. In the present study, we have used semiquantitative PCR to measure muscarinic receptor gene expression after 6, 12, and 24 hours of HH exposure at 25,000 feet using a decompression chamber in rat brain's PFC and cerebellum. We have found that CHRM1-CHRM5 downregulated after acute exposure to hypoxia until 12 hours, and then, the expression level of these receptors increased to 24 hours when compared with 12 hours in PFC. All subtypes have shown a similar pattern in PFC regions under hypoxia exposure. On the other hand, these receptors have shown altered expression at different time points in the cerebellum. CHRM1 and CHRM4 acutely downregulated, CHRM2 and CHRM5 downregulated, while CHRM3 upregulated after hypoxia exposure. Our study, for the first time, has shown the altered expressions of muscarinic receptors under temporal hypoxia exposure. The altered expression pattern has shown an association with acclimatization and protection against necrosis due to hypoxia. This study may pave further investigations for understanding and addressing the cognitive, behavioral, and physiological impacts of hypoxia and therapeutic development.

Gstir, Claudia, Timo Schurr, Roxana Ehlers, Johannes Burtscher, Barbara Sperner-Unterweger, and Katharina Hüfner. Is it possible for individuals with pre-existing mental disorders to perform mountain sports at high altitude-First evidence from a pilot cross-sectional questionnaire study. 00:00-00, 2024. Mountain sports at high altitude (HA) are gaining increasing popularity, but little is known about the effect of such activities on mental health, despite a great prevalence of mental disorders. Data were collected using an online self-report questionnaire assessing mental and somatic disorders in individuals performing mountain sports at HA (>2,500 m above sea level [ASL]) as well as their symptom change. Nonparametric tests were used for analyses. 251 individuals without pre-existing disorders (noD), 34 with somatic disorders (somaD), and 38 with mental disorders (mentalD; mainly depressive, eating, and anxiety disorders) participated in this study. Overall, 44.7% of the mentalD group compared with 14.7% of somaD experienced ameliorated symptoms during mountain sports at HA, while 2.6% and 8.8%, respectively, reported a worsening (χ[2] =8.13, = 0.017). People in the mentalD compared with somaD group significantly less frequently inform tour partners (41.9% vs. 90.9%; χ[2]=16.69, < 0.001) about their condition or consult their physician (2.6% vs. 26.5%; χ[1]=8.53, = 0.003) regarding their plans to perform mountain sports at HA. 14.5% of all participants reported mental symptoms at 2,500-3,500 m ASL, 23.5% between >3,500-5,500 m ASL and 31.8% >5,500 m ASL. Individuals with mental disorders often report improved mental health during mountain sports at HA, possibly due to a combination of physical activity, the alpine natural environment, and/or moderate hypoxia. The fact that tour partners and physicians are rarely informed shows the need to reduce the stigma of mental disorders in the mountain sports community. The study was prospectively registered with the German Clinical Trials Registry (DRKS00024949).

Poirier, Anne, Amélie Basso, Sarah Bonnet-Ducrot, Ellen Katranji, Sophia Cherif-Alami, Sophie Chateigner-Coelsch, Manon Navarre, Cécile Ricard, and Corentin Tanné. Clinical Effect of Descent in Infants with Bronchiolitis Diagnosed at Altitude: A Prospective Multicenter Study. 00:00-00, 2024. This study aims to assess the clinical impact of descending to a lower altitude in infants with bronchiolitis diagnosed at an altitude above 1,000 m. We performed a prospective, observational, multicenter study during two consecutive winters (2022-2023 and 2023-2024). The diagnosis was made by local general practitioners (GPs) who then sent the patients who were younger than 1 year and had a Wang respiratory score (WRS) ≥4 to any of the five emergency departments (EDs) located at lower altitudes. The WRS, peripheral oxygen saturation (SpO), and respiratory rate (RR) recorded by the GPs and at the EDs were compared. We included 74 infants (59% females, median age 5.4 [3.6-8.0] months). Compared with the median values recorded by the GPs at altitudes above 1,000 m, the median values at the lower-altitude EDs were significantly better for the WRS (5.0 vs. 6.0, = 0.002), RR (50/min vs. 60/min, = 0.001), and SpO (97.0% vs. 91.5%, < 0.001). Descending to a lower altitude significantly improved respiratory function in infants younger than 1 year with bronchiolitis diagnosed at altitudes above 1,000 m.

Yufei Wang, Qiong Meng, Jin Zhang, Bing Guo, Nanyan Li, Qian Deng, Julinling Hu, Deji Quzong, Han Guan, Danzhen Wangjiu, Hui Yu, Zhifeng Li, and Junmin Zhou. Altitude and metabolic dysfunction-associated fatty liver disease (MAFLD) in China: a population-based study. 00:00-00, 2024. The epidemiological evidence for the relationship between altitude and metabolic dysfunction-associated fatty liver disease (MAFLD) is scarce. This study aims to examine the altitude-MAFLD relationship and explore the potential mediators explaining the relationship. Data were derived from the China Multi-Ethnic Cohort. The participants' altitude information was extracted from their residential addresses. MAFLD was diagnosed based on radiographically confirmed hepatic steatosis and any one of the following three items: overweight/obese status, diabetes mellitus, or metabolic dysregulation. We performed multivariable logistic regression and mediation analyses to assess the altitude-MAFLD associations and potential mediators, respectively. In the mediation analysis, mediation proportion is an estimate of the extent to which the total effect (altitude-MAFLD association) is accounted for by the pathway through the mediators. In total, 87,679 participants (female: 60.7%, mean age: 51.36 years) were included. The odds ratio of MAFLD was 1.61 (95% confidence interval [CI]: 1.52-1.71) between high and low altitudes, 1.52 (95% CI: 1.43-1.62) between high and middle altitudes, and 1.06 (95% CI: 1.01-1.10) between middle and low altitudes. Of the total estimated effect between high and low altitude, physical activity and vegetable intake accounted for 15.7% (95% CI: 12.8-19.1) and 3.8% (95% CI: 1.2-6.6), respectively. Of the total estimated effect between high and middle altitude, physical activity and vegetable intake accounted for 31.4% (95% CI: 26.2-34.8) and 2.3% (95% CI: 0.6-3.8), respectively. Of the total estimated effect between middle and low altitude, vegetable intake accounted for 11.8% (95% CI: 3.2-61.5). Higher altitude was associated with increased odds of MAFLD, and physical activity and vegetable intake mediated such association. Multifaceted efforts should be taken in public health to promote healthy lifestyles among higher altitude residents.

Joyce, Kelsey E., Catherine A. Campbell, Arthur R. Bradwell, Samuel J.E. Lucas, Christopher T. Lewis, Rebekah A.I. Lucas, and Mark Edsell. The environmental impact of a high-altitude medical research expedition. 00:00-00, 2024. Scientists must begin examining the environmental cost(s) of their research. The purpose of this study was to evaluate a component of the environmental impact of a high-altitude medical research expedition by totaling the carbon dioxide (CO) emissions calculated from as many direct and indirect sources as possible. Eighteen individuals flew from London to Bagdogra (via Delhi), and then drove onward to Lachung (via Gangtok) where they began their ascent on foot to 4,800 m (Kanchenjunga National Park, Sikkim). Several research experiments were conducted throughout the expedition, which required use of a laboratory centrifuge, solid CO (specimen storage), rechargeable laptop computers and battery-powered oximeters. International Civil Aviation Organization calculators estimated aviation CO production. Land emissions were calculated for vehicles. Solid waste was weighed and CO emissions estimated for its incineration. Total CO emissions equated to ∼16.7 tonnes from the following sources: air and land transportation of expedition team (87.3%); sublimation and transportation of solid CO (7.7%), waste incineration (0.58%), generator transportation and gasoline (12 l) combustion (0.48%), and battery transportation (3.3%). Air travel contributed the most to the overall environmental cost of the research expedition. Further investigation is required to contextualize these findings in relation to lab-based alternative(s).