Background: Numerous studies have shown that air pollution is a serious public health threat and risk worldwide. Mongolia is the world leader in outdoor and indoor air pollution, and the morbidity and mortality caused by it are increasing every year. People spend most of their lives indoors, and it is necessary to regularly assess and study indoor air pollution. Aim: To study the concentration of PM2.5 particles in the indoor air of households in Ulaanbaatar and Darkhan cities in relation to some symptoms of respiratory diseases. Materials and Methods: The study was conducted using an analytical cohort design from October 2023 to July 2025, and the 4 districts of the central Ulaanbaatar city and Darkhan cities were included in the study. A total of 240 households were included in the study, including 48 households living in ger and house, 24 households living in apartments, and 48 households living in ger and house, and 24 households living in apartments from Ulaanbaatar city. A direct measurement device (PurpleAir) was installed in the households for 3-4 weeks to measure PM2.5 particles in the indoor air for 24 hours. After measuring PM2.5 particles in the indoor air of the household, data were collected through questionnaires from the participants aged 18-60 who participated in the study and underwent health examinations. The results were processed using STATA-19.0 and R programs. Result: 213-239 households were selected for the study, including households living in 17-26 apartments, 42-58 houses, and 38-50 houses. The 24-hour average concentration of PM2.5 particles in the ambient air of households in Ulaanbaatar city was measured relatively higher in winter and summer than in households in Darkhan city. Among the districts of Ulaanbaatar city, the highest concentration of PM2.5 particles was measured in Songinokhairkhan district, and the lowest concentration was measured in Bayanzurkh district. Considering the cities by heating type, households with stoves are more polluted than households with centralized heating. In Darkhan city, the lowest concentration was measured in apartments (22.78-31.53 μg/m³), houses (44.53-68.17 μg/m³), and the highest concentration was measured in traditional felt houses (houses) (63.20-68.25 μg/m³). In Ulaanbaatar, PM2.5 concentrations were relatively high in all types of housing, including apartments (41.61-58.37 μg/m³), houses (79.22-92.50 μg/m³), and traditional felt dwellings (76.69-86.31 μg/m³). In the summer, PM2.5 concentrations in Darkhan were 3.10-10.03 μg/m³ in apartments, 7.67-14.37 μg/m³ in houses, and 7.98-17.90 μg/m³ in traditional felt dwellings (houses). The concentration of PM2.5 particles in the ambient air of the settlement is statistically significantly associated with shortness of breath, fatigue, weakness, muscle pain, nausea, palpitations, sneezing, runny nose, conjunctivitis, pain in the eye socket, tearing of the eyes, headache, fever, nasal congestion, cough, loss of appetite, sore throat, phlegm, wheezing, and chest pain. Conclusion The 24-hour average concentration of PM2.5 particles in indoor air in households in Ulaanbaatar and Darkhan cities is higher than the Mongolian standard during winter and is statistically significantly associated with some symptoms of respiratory diseases.

Background: Polymyositis (PM) is a rare idiopathic inflammatory myopathy characterized by symmetric proximal muscle weakness, elevated muscle enzyme levels, dysphagia, and respiratory muscle weakness. Rhabdomyolysis is a potentially life-threatening condition caused by extensive skeletal muscle breakdown, resulting in myoglobinuria and an increased risk of acute kidney injury and multiorgan complications. The coexistence of rhabdomyolysis in patients with polymyositis is uncommon and may complicate both diagnosis and management. Case Presentation: A 65-year-old man was admitted with fever up to 39°C, generalized skin rash, dysphagia, progressive muscle weakness, dyspnea, decreased urine output, and dark tea-colored urine. Physical examination revealed symmetric proximal muscle weakness, with muscle strength graded 3/5 in both upper extremities and 4/5 in both lower extremities. Neck muscle strength was 4/5. Dysphagia and a generalized skin rash were also present. Laboratory investigations showed markedly elevated creatine kinase (CK) at 9,943.1 U/L, alanine aminotransferase (ALT) at 449.1 U/L, aspartate aminotransferase (AST) at 222.1 U/L, lactate dehydrogenase (LDH) at 1,342.9 U/L, and C-reactive protein (CRP) at 70.6 mg/L. Urinalysis showed blood 3+ and protein 2+, while no erythrocytes were detected on urine sediment microscopy. Electromyography demonstrated myopathic changes, and muscle biopsy revealed inflammatory infiltrates and necrotic muscle fibers. Conclusion Comprehensive assessment of clinical manifestations, laboratory findings, autoantibody testing, electrophysiological studies, and muscle biopsy is essential for the diagnosis of polymyositis complicated by rhabdomyolysis. An integrated diagnostic approach facilitates confirmation of the diagnosis, differentiation from clinically similar disorders, and appropriate treatment selection. Early recognition of rhabdomyolysis and other potentially life-threatening complications is crucial for preventing organ damage and improving patient outcomes.

Background: Ambient and household air pollution remain leading risk factors for global morbidity and mortality. Exposure to fine particulate matter (PM₂.₅) is associated with increased risks of cardiovascular and respiratory diseases, as well as lung cancer, metabolic and neurological disorders, and immune dysfunction. In urban areas of Mongolia, air pollution reaches critical levels during the winter season. Although improved solid fuels have been introduced in recent years, their impact on both outdoor and indoor air quality remains insufficiently characterized. Aim: To compare outdoor and household air pollution levels in Ulaanbaatar and Darkhan cities. Materials and Methods: Outdoor air pollution data for Ulaanbaatar were obtained from fixed monitoring stations of the National Agency for Meteorology and Environmental Monitoring for the period 2014–2026, with seasonal comparisons performed. For indoor air quality assessment, a longitudinal study was conducted among 240 households (apartments, houses, and traditional gers) in Ulaanbaatar and Darkhan from 2023 to 2026. PM₂.₅ concentrations were measured using real-time sensors (PurpleAir sensor), deployed for 14–21 days per season (winter and summer) in each household, recording data at 10-minute intervals over 24-hour periods. Result: Between 2014 and 2026, the 24-hour mean concentrations in Ulaanbaatar were 60.5 µg/m for PM₂.₅, 117.3 µg/m for PM₁₀, 37.3 µg/m for NO₂, 41.8 µg/m for SO₂, and 27.5 µg/m for O₃. While particulate matter levels showed a decreasing trend following the introduction of improved fuels, SO₂ concentrations increased, and overall pollution levels remained higher than those observed in Darkhan. Indoor PM₂.₅ concentrations were higher in Ulaanbaatar compared to Darkhan (60.7±86.1 vs 48.4±96.7 µg/m). Significant differences were observed by housing type (p<0.0001), with higher concentrations in households using solid fuels (houses and gers) and lower levels in apartments. These findings indicate substantial variability in indoor air pollution by city, housing type, and season, with persistently elevated exposure levels. Conclusion Outdoor air pollutant concentrations in Ulaanbaatar, including particulate matter, NO₂, and SO₂, exceed national standards and WHO guideline values by 1–4 times. Indoor PM₂.₅ pollution is higher in Ulaanbaatar than in Darkhan and varies significantly by housing type and season, indicating a high and heterogeneous exposure burden among urban populations.

Background: Respiratory and gastrointestinal infectious diseases are the leading causes of morbidity in children. Numerous international studies have demonstrated that handwashing with soap is one of the most effective and cost-efficient methods for preventing these diseases in children. A previous study conducted in Ulaanbaatar found that only 50.1% of general education school students practiced proper handwashing, which is considered insufficient even in areas with relatively adequate facilities. In Mongolia, 56.1% of the 865 schools lack handwashing facilities and soap, and 25% do not meet the WASH standards. Although knowledge about handwashing increased during the COVID-19 pandemic, sustained behavioral change remained limited, highlighting a gap between knowledge and practice and indicating the need for targeted educational interventions. Furthermore, there is limited research comparing the effectiveness of such interventions across different school environments and urban–rural settings, which provides the rationale for this study. Aim: To evaluate the effectiveness of a handwashing educational intervention among primary school students and determine differences in knowledge change across four schools in urban and rural areas. Materials and Methods: A quasi-experimental study design was used from December 2024 to June 2025. A total of 1,353 students from grades 3–5 in four general education schools (two in Ulaanbaatar and two in rural areas) were included in the study. Preand post-intervention handwashing knowledge scores were analyzed using paired t-tests and one-way ANOVA (α=0.05) with STATA 14.0. Ethical approval was obtained from the Ethics Committee of the Mongolian National University of Medical Sciences. Result: The mean handwashing knowledge score increased significantly from 9.68 (±2.64) before the intervention to 10.30 (±2.74) after the intervention, with a mean difference of +0.63 (p<0.001). The differences in improvement between schools were also statistically significant (ANOVA: F(3,1335)=5.90, p=0.0005). The highest improvement was observed in urban School A (+1.49), while the lowest was observed in School B (+0.16). Rural schools C and D showed moderate and relatively consistent improvements (+0.51 and +0.70, respectively). Conclusion School-based handwashing educational interventions effectively improve knowledge among primary school students. However, environmental factors, such as infrastructure and geographic location, significantly influence the effectiveness of the intervention. Therefore, educational interventions should be implemented alongside infrastructure improvements.

Background: According to the World Health Organization (WHO), 6.7 million people die annually due to air pollution caused by solid fuel use, with the majority of deaths resulting from respiratory diseases and cardiovascular conditions. In Mongolia, air pollution ranks as the fourth leading risk factor contributing to mortality, following hypertension, diabetes, and other major health risks. Although there have been numerous studies on outdoor air pollution in Mongolia, research linking indoor air pollution at the household level with the health status of residents remains limited. Aim: To compare indoor PM2.5 concentrations in households of Ulaanbaatar and Darkhan and examine their association with hypertension during the winter season. Materials and Methods: The study was conducted during November and December 2023, and January 2024, involving 240 households in Ulaanbaatar and Darkhan. Indoor PM2.5 concentrations were measured using Purple Air real-time sensors continuously for 24 hours over approximately one month. After measuring indoor air pollution, individuals aged 18–60 years living in the selected households were recruited based on specific inclusion criteria. Blood pressure was measured three times and the average value was recorded. Information on respiratory illnesses was collected through structured questionnaires. Statistical analysis was performed using STATA version 19.0. Results: A total of 241 households participated in the study, with 116 from Ulaanbaatar and 125 from Darkhan. Of the participants, 46.5% were male and 53.5% were female. In terms of housing type, 96 households (39.8%) lived in gers, 97 (40.2%) lived in stove-heated houses, and 48 (19.9%) lived in apartments. Among all participants, 66.0% (n=159) had hypertension and 34.0% (n=79) had normal blood pressure. Among participants aged over 40, 69.9–88.5% had hypertension, which is statistically significantly higher compared to younger individuals (p=0.0001). By body mass index, 75.3% (n=72) of overweight individuals and 78.4% (n=58) of obese participants had hypertension, showing a statistically significant difference compared to participants with normal weight (p=0.0001). The 24-hour average concentration of indoor PM2.5 was measured using the Purple Air device, and the levels in gers and stove-heated houses exceeded the limit set by the MNS 4585:2025 standard (37.5 µg/m³) Conclusion This study identified a relationship between environmental factors, such as air pollution and housing type, and the prevalence of hypertension. The indoor PM2.5 concentration in gers and stove-heated houses was above the standard limit, indicating a negative impact on the health of those residents. Furthermore, the high prevalence of hypertension among participants over the age of 40 and those who are overweight suggests a possible link to lifestyle and environmental conditions.

Background: Particulate matter in ambient air is an important risk factor for cardiovascular and respiratory diseases. Accurate and appropriate air quality monitoring is therefore critical for public health. In this context, it is necessary to investigate the feasibility of using low-cost direct monitoring devices (such as PurpleAir) in outdoor environments during the winter season, particularly in urban areas where fixed monitoring stations are not available. Aim: To assess and compare the outdoor PM2.5 concentrations in Ulaanbaatar and Darkhan during the winter season. Materials and Methods: The study was conducted in the capital city of Mongolia. The data collected for 45 days during the winter season, from December 9, 2024 to February 14, 2025. Continuous low-cost sensor was collected using a light scattering device (PurpleAir Classic) at a total of 25 locations and for 24 hours. Of these, 1 location was located next to a fixed measurement point and 3 locations (Zuun 4 zam, Yarmag, Selbe) were located within 200m of the study area, and the measurement results were compared using PM2.5. We used R software for statistical analysis. Results: The average PM2.5 concentration measured at the 13 fixed monitoring sites during the study period was 65 μg/ m³, while the average from the 25 PurpleAir sensors was 88 μg/m³. Parallel measurements conducted with the PurpleAir sensors and the UB4 fixed monitoring station showed a moderate correlation (r=0.44, R²=0.22, p<0.05). The measurement results at the Zuun 4 zam, Yarmag, and Selbe locations have a moderate correlation (r=0.38, r=0.61, r=0.25). Conclusion In situations where it is not possible to measure PM2.5 particulate matter in outdoor air automatically or by conventional methods, it is possible to monitor air quality by measured by low-cost sensors.

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: An estimated 99% of the global population lives in environments where PM2.5 levels exceed the WHO air quality guideline of 15 μg/m³. In 2018, air pollution contributed to approximately 4.2 million deaths worldwide. In Mongolia, air pollution—particularly in urban centers like Ulaanbaatar, worsens significantly during the winter season, posing a serious public health and local concern. Therefore, it is compulsory to compare the outdoor air quality in Ulaanbaatar, the capital and Darkhan city. Aim: To assess and compare the outdoor PM2.5 concentrations in Ulaanbaatar and Darkhan during the winter season. Materials and Methods: This study was conducted in Ulaanbaatar and Darkhan from December 10, 2024, to February 19, 2025. A total of 60 PurpleAir Classic+ sensors (30 per city) were installed to assess PM2.5 concentrations at 2-minute intervals. We analyzed collected data using R software. The 24-hour average PM2.5 concentrations were compared with both the Mongolian National Air Quality Standard (MNS4585:2016) and the WHO air quality guidelines (2021). Results: The 24-hour average PM2.5 concentration in Ulaanbaatar was 112.3±62.2 μg/m³, which was significantly higher than that in Darkhan (79.2±25.6 μg/m³; p<0.05). In Ulaanbaatar, the monthly averages were 119.9±67.7 μg/m³ (Decem ber), 113.5±60.8 μg/m³ (January), and 95.0±51.9 μg/m³ (February) respectively (p<0.05). In contrast, Darkhan city’s monthly average PM2.5 remained relatively close across the months: 79.1±22.2 μg/m³ (December), 78.7±28.6 μg/m³ (January), and 84.6±30.0 μg/m³ (February), with no statistical significance (p>0.05). During the study period, the 24-hour average PM2.5 concentrations exceeded the MNS4585:2016 (50 μg/m³) in 69.8% of days in Ulaanbaatar and 64.6% in Darkhan. WHO’s guideline of 15 μg/m³ was exceeded 93.4% of the time in both cities. Conclusion Darkhan city has lower PM2.5 concentrations compared to Ulaanbaatar, both cities significantly exceeded MNS4585:2016 standard and the WHO air quality guidelines (2021) during the winter months.

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.