Background: According to the World Health Organization (WHO), 99 percent of the world’s population is exposed to air that exceeds WHO recommendations, with low- and middle-income countries being the most affected. The main causes of indoor air pollution include human activities such as fuel burning, cooking, cleaning, and smoking; housing characteristics such as walls, floors, ceilings, and furniture; ventilation; and outdoor air pollution. Aim : To assess PM1 and PM10 concentrations in 120 selected households in Ulaanbaatar. Materials and Methods : Indoor PM1 and PM10 concentrations were measured using Purple Air real-time sensors in randomly selected Ulaanbaatar households between October 2023 and January 2024. Supplementary data on factors affecting the PM2.5 concentration were collected via questionnaires. Each measurement was taken in 10-minute intervals, yielding 51,309 data for analysis. Results : PM1 concentrations were measured at 55.5±53.2 μg/m³ in gers, 54.9 ± 46.7 μg/m³ in houses, and 31.6±40.1 μg//m³ in apartments (p<0.001) and measuring PM10 concentrations were 110.6±108.6 μg/m³ in gers, 110.6±96.7 μg/m³ in houses, and 62.2±83.0 μg/m³ in apartments (p<0.001) When considering the concentration of PM1, PM10 by heating type, PM1 was 55.3±50.1 μg/m³ and PM10 was 110.6±103.0 μg/m³ in households with stoves and furnaces, and PM1 was 31.6±40.1 μg/m³ and PM10 was 62.2±83.0 μg/m³ in households connected to the central heating system (p<0.001). Regarding the months of measurement, the highest concentration was observed in December 2023, at 77.1±94.1 μg/m³. The highest concentrations for both PM₁ and PM₁₀ were recorded in January 2024, at PM₁: 64.8±55.1 μg/m³, PM₁₀: 131.4±116.0 μg/m³. Conclusion 1. Indoor PM10 concentrations in residential environments in Ulaanbaatar city were within the MNS4585:2016 Air Quality Standard, however, it was exceeded the WHO air quality guidelines, indicating an excessive risk of increasing morbidity and mortality among the population. 2. Indoor PM1 and PM10 concentrations in residential environments in Ulaanbaatar varies depending on location, type of housing, type of heating, and month of measurement.

Background: Demyelinating disorders are a group of chronic immune-mediated diseases affecting myelinated axons in the central nervous system, which lead to life-long disability. In Mongolia, the last regional prevalence study was conducted in 2010. Our study objective is to describe the current prevalence of multiple sclerosis (MS) and other demyelinating disorders in Mongolia. : Aim Materials and Methods: We registered MS, neuromyelitis optica spectrum disease (NMOSD), myelin oligodendrocyte glycoprotein (MOG), and acute disseminated encephalomyelitis (ADEM) cases diagnosed according to the 2017 McDonald criteria, the 2023 NMOSD diagnostic criteria, International MOGAD Panel proposed criteria. Results: The study was conducted in all tertiary, 7 regional, and 20 provincial hospitals across Mongolia and has collected comprehensive data on 965 patients. The prevalence of total demyelinating disorders was estimated to be 27.2, MS 15.6, NMOSD 5.6, MOG 0.06, and ADEM 0.9 per 100,000 total population, respectively. The prevalence of demyelinating disorders between provinces was compared in order of geographical latitude, from lowest to highest, and was statistically significant. Latitude is associated strongly with the prevalence of demyelinating disorders (p=0.006, 95% CI 14.3-22.4, Pearson correlation=0.603) and moderately with the prevalence of MS (p=0.028, 95% CI 9.39-15.6, Pearson correla tion=0.503). Conclusion In Mongolia, the prevalence of MS has significantly increased and can be considered at medium risk, but still much lower than that in Western countries. The prevalence of NMOSD is almost similar to other Asian countries. An obvious latitude gradient for demyelinating disorders was observed in the Mongolian population.

Backgroun: Air pollution is a major global public health concern that poses serious risks to human health regardless of a country’s level of economic or technological development. According to the World Health Organization (WHO, 2021), nine out of ten people worldwide breathe polluted air, and air pollution is responsible for the deaths of approximately 800 people every hour and 13 people every minute. Prolonged exposure to polluted air has been linked to a wide range of chronic illnesses, including chronic obstructive pulmonary disease (COPD), lung and bronchial cancers, asthma, and stroke. In Mongolia, air pollution reaches its highest levels during the winter months, particularly in Ulaanbaatar, where the majority of the country’s population resides. A study conducted by Enkhjargal G. (2012) reported that the concentrations of PM10 and PM2.5 in Ulaanbaatar were 7–8 times higher than the WHO recommended guidelines. In response to such challenges, many countries have increasingly adopted low-cost, direct measurement devices such as PurpleAir to monitor air quality. These devices are valued for their accessibility, network connectivity, and potential role in smart city pollution management systems. Despite their global application, there remains a lack of research in Mongolia on the use of PurpleAir sensors to measure PM2.5 concentrations and compare the results with official monitoring station data. Addressing this gap is essential for improving local air quality monitoring capacity and informing effective public health and environmental policies. Aim: Determination of PM2.5 particulate matter pollution in the outdoor environment of Ulaanbaatar city using a direct measurement device (Purple Air). Materials and Methods: A cross-sectional study design was employed. Direct measurement devices (Purple Air) were installed in selected districts of central Ulaanbaatar between December 2024 and February 2025, measuring PM2.5 concentrations at two-minute intervals over 24-hour periods. All data were statistically processed and analyzed using the SPSS-26 software package. Results: The average concentration of PM2.5 particles in the air of Ulaanbaatar city in winter is 66.68 μg/m3. Compared to the districts, the highest concentration was determined in SKHD (118.58±90.22 μg/m3), while the lowest concentration was determined in KHUD (42.37±43.51 μg/m3). Compared to the days of the week, the highest concentrations were measured on Monday (76.68±71.98 μg/m³), Saturday (77.50±71.63 μg/m³), and Sunday (80.34±74.45 μg/m³). The highest concentration of PM2.5 particles occurred from 6 pm to 1 am, and the lowest concentration was measured during the day (between 2 pm and 4 pm). The highest concentration of PM2.5 was measured in December (74.22±73.45 μg/m3), while the lowest concentration was measured in February (50.25±57.44 μg/m3). Conclusion The concentration of PM2.5 in the air of Ulaanbaatar city is 1.7 times higher than the general standard and technical requirements of Mongolia in winter, and the highest concentration is in the SKHD. The highest concentration of PM2.5 occurs more often in December and at night than in the winter months.

Background: Particulate matter with an aerodynamic diameter of 2.5 micrometers or smaller (PM2.5) penetrates deep into the alveoli through the respiratory tract and is characterized by its ability to induce oxidative stress, systemic inflammation, and vascular inflammation. Mongolia ranks among the countries with the highest levels of air pollution. In Ulaanbaatar, where more than half of the country’s population resides, wintertime PM2.5 concentrations often exceed 200 μg/m³, which is about eight times higher than the World Health Organization (WHO) guideline value. A study involving 1,200 adults in Ulaanbaatar showed that quality of life deteriorated sharply during periods of high air pollution, with effects more pronounced among individuals who already had impaired respiratory function. Aim: To examine the relationship between indoor household PM2.5 concentrations and lung function indicators among adults in Ulaanbaatar and Darkhan. Materials and Methods: This analytical cross-sectional study recruited adult participants from Ulaanbaatar and Darkhan through targeted sampling. Household air quality was measured using PurpleAir sensors, which were installed in participants’ homes for one month. After exposure measurement, lung function was assessed via spirometry. Statistical analyses were conducted using SPSS version 25.0. Results: A total of 236 participants were included: 114 (48.3%) from Ulaanbaatar and 122 (51.7%) from Darkhan. The sample consisted of 111 men (47.0%) and 125 women (53.0%). The mean indoor PM2.5 concentration was 66.24 μg/m³ (SD 44.87 μg/m³), ranging from a minimum of 7.79 μg/m³ to a maximum of 264.55 μg/m³. Stratification by housing type showed the highest PM2.5 levels in gers (82.34 μg/m³), followed by detached houses (67.34 μg/m³), while apartments had the lowest concentrations (32.24 μg/m³). Correlation analysis revealed statistically significant negative associations between PM2.5 levels and measures of expiratory function, including the FEV1/FVC ratio, peak expiratory flow (PEF), and mid-expiratory flow (FEF25–75). Reduced forced vital capacity (FVC) was observed in 9.4% of participants, reduced forced expiratory volume in one second (FEV1) in 15.3%, and a decreased FEV1/FVC ratio in 3.8%. Conclusion Indoor household PM2.5 concentrations were highest in gers, and expiratory flow-related lung function parameters showed significant negative associations with particulate exposure. This suggests that indoor PM2.5 primarily affects airflow limitation rather than overall lung volumes in this population.

Background: Hepatocellular carcinoma (HCC) remains one of the leading causes of cancer-related mortality worldwide and in Mongolia. Alcohol-related liver disease (ALD) and metabolic dysfunction-associated steatohepatitis (MASH) are two major etiological factors contributing to the rising burden of HCC, each presenting distinct clinical and pathological characteristics. Aim: To compare the clinical, pathological, and survival characteristics of patients with ALD-related HCC and MASH-related HCC who underwent liver resection. Material and Methods: A retrospective cohort study was conducted using clinical and pathological data from 980 patients who underwent liver resection between 2010 and 2024. Among them, 191 were categorized into the ALD group and 789 into the MASH group. Clinical parameters, laboratory findings, tumor pathology (size, grade, fibrosis stage, vascular invasion), recurrence, and overall survival (OS) were analyzed. A simulated Kaplan–Meier survival curve was generated based on group-level survival estimates. Results: Patients with ALD were significantly younger and predominantly male compared with those in the MASH group (p=0.0014; p<0.0001). The MASH group demonstrated more aggressive pathological features, including larger tumors (>5 cm), poorer differentiation (G3–4), advanced T4 stage, and a higher rate of large-vessel invasion (all p<0.05). Despite these findings, the MASH group showed a longer mean overall survival (92.6 months) than the ALD group (82.0 months; p=0.0206). Conclusion Although MASH exhibits more aggressive pathological features compared with ALD, patients in the MASH group demonstrated better overall survival. These findings underscore the importance of incorporating etiological differences into the diagnostic, therapeutic, and postoperative management strategies for HCC.

Purpose: To investigate the outcomes of ROP screening of retinopathy of prematurity (ROP). Methods: This was a prospective of prematurity infants screened ROP from 2020 April 13th to April 28th 2020 and from 2020 June 08 th to June 22th 2020 and prospective cohort study of premature infants with treatment-requiring ROP who received intravitreal injections, laser surgery. Demographic factors, diagnosis and clinical course were recorded. Indirect ophthalmoscopy and Retinal imaging was performed using RetCam (Natus Medical, Pleasanton, CA) and images were taken. Each eye was evaluated by the pediatric ophthalmologist and aimag’s ophthalmologist for the presence or absence of ROP, zone of vascularization, stage, plus disease, and aggressive posterior ROP (AP-ROP). The diagnosis and classification of ROP for this current study were determined by examination using indirect ophthalmoscopy, and treatment plans were determined according to the International Classification for ROP and the Early Treatment for ROP Study (ET-ROP).^2,13 Results: A total of 90 premature infants with BW ≤ 2000g and/or GA ≤ 34 weeks were screened for ROP during the study period. 8 (8.8%) of the 90 infants screened required treatment. The 8 infants who received ROP treatment had a mean GA of 28.5 ± 1.7 weeks, mean BW of 1237.5 ± 125.42g, mean PMA of 36 weeks and mean follow-up time of 2 months. Conclusion After treatment, resolution of ROP was noted in approximately 100 % of the patients who had treatment-requiring ROP.

Outcomes of retinopathy of prematurity screening Background: Retinopathy of prematurity (ROP) is a potentially blinding eye disorder that primarily affects premature infants weighing about 1250 grams or less that are born before 31 weeks of gestation (a full-term pregnancy has a gestation of 38-42 weeks). The smaller a baby is at birth, the more likely that baby is to develop ROP. This disorder — which usually develops in both eyes — is one of the most common causes of visual loss in childhood and can lead to lifelong vision impairment and blindness. ROP was first diagnosed in 1942. Our goal was to investigate the outcomes of ROP screening of retinopathy of prematurity (ROP). Materials and methods :This was a prospective of prematurity infants screened ROP from 2020 April 13th to April 28th 2020 and from 2020 June 08 th to June 22th 2020 and prospective cohort study of premature infants with treatment-requiring ROP who received intravitreal injections, laser surgery. Diagnosis and clinical course were recorded. Indirect ophthalmoscopy and Retinal imaging was performed using RetCam (Natus Medical, Pleasanton, CA) and images were taken. Each eye was evaluated by the pediatric ophthalmologist and aimag's ophthalmologist for the presence or absence of ROP, zone of vascularization, stage, plus disease, and aggressive posterior ROP (AP-ROP). The diagnosis and classification of ROP for this current study were determined by examination using indirect ophthalmoscopy, and treatment plans were determined according to the International Classification for ROP and the Early Treatment for ROP Study (ET-ROP). Results: A total of 90 premature infants with BW ≤ 2000g and/or GA ≤ 34 weeks were screened for ROP during the study period. 8 (8.8%) of the 90 infants screened required treatment. The 8 infants who received ROP treatment had a mean GA of 28.5 $ 1.7 weeks, mean BW of 1237.5 $ 125.42g, mean PMA of 36 weeks and mean follow-up time of 2 months. Conclusions: After treatment, resolution of ROP was noted in approximately 100 % of the patients who had treatment-requiring ROP

Purpose: To evaluate colorectal cancer localization in preoperative patients in Mongolia using CECTand endoscopyMaterials and Methods: Totally 10575 optic colonoscopy examinations were performed at UlaanbaatarSongdo Hospital between January 2009 and December 2012. From these examinations, colorectal cancerwas detected in 218 cases; from them 175 had CT examinations. From patients with CT examinations,111 underwent surgery at UBSH, National Cancer Center, State Central Hospital. (64MDCT SiemensSomatom). Only 86 patients with colorectal carcinoma proved by endoscopic or operative pathologywere included into this study. We retrospectively reviewed from the UBSH’ database their preoperativeCT, colonoscopy, surgical and pathohistologic reports using PACSPLUS, OCS operation systems. Toclassify colorectal tumor localization, we divided colon into 8 anatomic parts. The size of tumor wasmeasured as longest dimension visible on CT examination.Results: Study population’s age range was 25-87 age (mean 61.3years ±13.7SD). F: M= 48 (55.8%):38 (44.2%). Urban residents composed 58 (67.4%), rural- 27 (31.4%), foreigner- 1 (1.2%). Tumor sizerange on CT was 0-13 ñì (mean 6.5±2.2 ñì) . Colonoscopy and CT detected colorectal cancer in rectumin 30(34.9%) and 31 (36.1%), in sigmoid colon in 21(24.4%)’’’ and 19(22.1%), in hepatic flexure- 9(10.5%) and 9(10.5%), retrospectively. Double (synchronous) colorectal cancer was detected in 1(1.1%)at colonoscopy and in 2 (2.2%) at CT.Conclusions: The 60-69 age group composed the largest group (38.4%) in colorectal cancer patients,with slight predominance of urban residents over rural and higher female predilection. Sigmoid andrectum are shown to have highest incidence in colorectal cancer. To our best knowledge, it is firstpublication on detection of synchronous colorectal cancer in Mongoliaby both CT and colonoscopy.CT examination is less risky and reliable method to evaluate the entire colonic length in patients withcolorectal cancer suspicion, if observers are skilled in detection of CT signs of colorectal cancer.