1.Indoor Particulate Matter Concentration in Households of Darkhan City
Nyamdorj J ; Bolor M ; Maralmaa E ; Yerkyebulan M ; Ser-Od Kh ; Myagmarchuluun S ; Shatar Sh ; Gantuya D ; Gregory C. Gray ; Junfeng Zhang ; Ulziimaa D ; Damdindorj B ; Khurelbaatar N ; Davaalkham D
Mongolian Journal of Health Sciences 2025;85(1):25-29
Background:
A 2018 study on the global burden of disease, accidents, and risk factors reported that 1.6 million peo
ple died in 2017 due to household air pollution. Poor indoor air quality has been highlighted as a contributing factor to
respiratory diseases, cardiovascular conditions, and exacerbation of asthma and allergies. A 2019 study estimated that
long-term exposure to fine particulate matter (PM2.5) with a diameter of 2.5 micrometers or less reduces average life
expectancy by 1.8 years, with more severe effects in highly polluted regions. Additionally, a study by Miller et al. (2007)
found that prolonged exposure to PM2.5 increases the risk of cardiovascular diseases, particularly among women. Direct
measurement devices are highly effective in determining indoor PM2.5 concentrations, identifying sources of pollution,
tracking pollutant dispersion, and monitoring temporal variations. Studies suggest that direct measurement is an accurate,
cost-effective method that provides detailed data suitable for local conditions.
Aim:
To investigate the indoor air quality of houses and apartments in Darkhan city during the winter season using the
Purple Air monitoring device.
Materials and Methods:
A cross-sectional study was conducted with a targeted sample of 128 households in Darkhan
city. The study examined factors such as stove type, type of coal used, annual and daily coal consumption, frequency of
heating, and chimney sealing conditions. To collect data, the Purple Air monitoring device was installed in each house
hold for a month, after which it was retrieved. During retrieval, participants completed a questionnaire. The questionnaire
consisted of 55 questions across 7 pages at the time of device installation and 25 questions across 3 pages at the time of
device retrieval. The collected data was analyzed using SPSS 25.0.
Results:
A total of 128 households in Darkhan city participated in the study. The average duration of residence in the
current home was 9.5 years, with no statistically significant variation. The distribution of housing types was as follows:
traditional Mongolian gers (40.6%), houses (39.1%), and apartments (20.3%). The 24-hour average PM2.5 concentration
was highest in gers (70.9 μg/m³), followed by houses (46.8 μg/m³) and apartments (22.8 μg/m³), with a statistically significant difference (p=0.0001). PM2.5 levels were most variable in gers, followed by houses and then apartments. House
holds using central heating (apartments) had an average 24-hour PM2.5 concentration of 22.8 μg/m³, whereas households
using stoves (gers and houses) had a significantly higher concentration of 59.4 μg/m³ (p=0.0001). However, there was
no statistically significant difference between traditional and improved stoves. Among study participants, 21.4% reported
that someone in their household smoked indoors. Additionally, 86.5% regularly burned incense, candles, or herbs, while
99.2% did not use an air purifier.
Conclusion
The indoor particulate matter concentration in houses and gers in Darkhan was 59.4μг/m3. Variations in
stove types, poor chimney sealing limited space, and frequent gaps and cracks contribute to increased spread of indoor
air pollutants.
2.Bariatric surgery reduces long-term mortality in patients with metabolic dysfunction-associated steatotic liver disease and cirrhosis
Nicholas A. ROUILLARD ; Scott D. BARNETT ; Xinrong ZHANG ; Leslie KAM ; Richie MANIKAT ; Ramsey CHEUNG ; Mindie H. NGUYEN
Clinical and Molecular Hepatology 2025;31(1):227-239
Background/Aims:
With the obesity pandemic, metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common liver disease and a leading cause of end-stage liver disease and liver-related deaths in the USA. Therefore, we aimed to compare the long-term outcomes of patients with MASLD and cirrhosis with and without bariatric surgery.
Methods:
Patients were retrospectively identified from the California Department of Healthcare Access and Information database, 2005 to 2019, for a population-based cohort study. Propensity score matching (PSM) was used to balance background risks between patients with cirrhosis who underwent bariatric surgery and those who did not. Overall, liver-related and non-liver-related mortality were analyzed.
Results:
Of 91,708 eligible patients with MASLD and cirrhosis, PSM yielded 2,107 patients who underwent bariatric surgery and 8,428 non-bariatric controls. Compared to matched controls, patients who underwent bariatric surgery had lower 5-year overall (24.9% vs. 37.1%; p<0.0001), liver-related (3.3% vs. 14%; p<0.0001), and non-liver-related mortality (22.3% vs. 26.9%; p=0.046). In multivariable analysis, bariatric surgery was associated with decreased overall mortality (adjusted hazard ratio [aHR]=0.63; p<0.0001), liver-related (aHR=0.24; p<0.0001), and non-liverrelated (aHR=0.81; p=0.0026) mortality. However, only laparoscopic surgeries were associated with lower overall mortality (aHR=0.39; p<0.0001) whereas open surgeries were associated with higher overall mortality (aHR=1.24; p=0.022).
Conclusions
Patients with MASLD and cirrhosis who underwent bariatric surgery, specifically laparoscopic approaches, had significantly lower mortality risk than non-surgical counterparts.
3.Bioactive metabolites: A clue to the link between MASLD and CKD?
Wen-Ying CHEN ; Jia-Hui ZHANG ; Li-Li CHEN ; Christopher D. BYRNE ; Giovanni TARGHER ; Liang LUO ; Yan NI ; Ming-Hua ZHENG ; Dan-Qin SUN
Clinical and Molecular Hepatology 2025;31(1):56-73
Metabolites produced as intermediaries or end-products of microbial metabolism provide crucial signals for health and diseases, such as metabolic dysfunction-associated steatotic liver disease (MASLD). These metabolites include products of the bacterial metabolism of dietary substrates, modification of host molecules (such as bile acids [BAs], trimethylamine-N-oxide, and short-chain fatty acids), or products directly derived from bacteria. Recent studies have provided new insights into the association between MASLD and the risk of developing chronic kidney disease (CKD). Furthermore, alterations in microbiota composition and metabolite profiles, notably altered BAs, have been described in studies investigating the association between MASLD and the risk of CKD. This narrative review discusses alterations of specific classes of metabolites, BAs, fructose, vitamin D, and microbiota composition that may be implicated in the link between MASLD and CKD.
4.Bariatric surgery reduces long-term mortality in patients with metabolic dysfunction-associated steatotic liver disease and cirrhosis
Nicholas A. ROUILLARD ; Scott D. BARNETT ; Xinrong ZHANG ; Leslie KAM ; Richie MANIKAT ; Ramsey CHEUNG ; Mindie H. NGUYEN
Clinical and Molecular Hepatology 2025;31(1):227-239
Background/Aims:
With the obesity pandemic, metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common liver disease and a leading cause of end-stage liver disease and liver-related deaths in the USA. Therefore, we aimed to compare the long-term outcomes of patients with MASLD and cirrhosis with and without bariatric surgery.
Methods:
Patients were retrospectively identified from the California Department of Healthcare Access and Information database, 2005 to 2019, for a population-based cohort study. Propensity score matching (PSM) was used to balance background risks between patients with cirrhosis who underwent bariatric surgery and those who did not. Overall, liver-related and non-liver-related mortality were analyzed.
Results:
Of 91,708 eligible patients with MASLD and cirrhosis, PSM yielded 2,107 patients who underwent bariatric surgery and 8,428 non-bariatric controls. Compared to matched controls, patients who underwent bariatric surgery had lower 5-year overall (24.9% vs. 37.1%; p<0.0001), liver-related (3.3% vs. 14%; p<0.0001), and non-liver-related mortality (22.3% vs. 26.9%; p=0.046). In multivariable analysis, bariatric surgery was associated with decreased overall mortality (adjusted hazard ratio [aHR]=0.63; p<0.0001), liver-related (aHR=0.24; p<0.0001), and non-liverrelated (aHR=0.81; p=0.0026) mortality. However, only laparoscopic surgeries were associated with lower overall mortality (aHR=0.39; p<0.0001) whereas open surgeries were associated with higher overall mortality (aHR=1.24; p=0.022).
Conclusions
Patients with MASLD and cirrhosis who underwent bariatric surgery, specifically laparoscopic approaches, had significantly lower mortality risk than non-surgical counterparts.
5.Bioactive metabolites: A clue to the link between MASLD and CKD?
Wen-Ying CHEN ; Jia-Hui ZHANG ; Li-Li CHEN ; Christopher D. BYRNE ; Giovanni TARGHER ; Liang LUO ; Yan NI ; Ming-Hua ZHENG ; Dan-Qin SUN
Clinical and Molecular Hepatology 2025;31(1):56-73
Metabolites produced as intermediaries or end-products of microbial metabolism provide crucial signals for health and diseases, such as metabolic dysfunction-associated steatotic liver disease (MASLD). These metabolites include products of the bacterial metabolism of dietary substrates, modification of host molecules (such as bile acids [BAs], trimethylamine-N-oxide, and short-chain fatty acids), or products directly derived from bacteria. Recent studies have provided new insights into the association between MASLD and the risk of developing chronic kidney disease (CKD). Furthermore, alterations in microbiota composition and metabolite profiles, notably altered BAs, have been described in studies investigating the association between MASLD and the risk of CKD. This narrative review discusses alterations of specific classes of metabolites, BAs, fructose, vitamin D, and microbiota composition that may be implicated in the link between MASLD and CKD.
6.Bariatric surgery reduces long-term mortality in patients with metabolic dysfunction-associated steatotic liver disease and cirrhosis
Nicholas A. ROUILLARD ; Scott D. BARNETT ; Xinrong ZHANG ; Leslie KAM ; Richie MANIKAT ; Ramsey CHEUNG ; Mindie H. NGUYEN
Clinical and Molecular Hepatology 2025;31(1):227-239
Background/Aims:
With the obesity pandemic, metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common liver disease and a leading cause of end-stage liver disease and liver-related deaths in the USA. Therefore, we aimed to compare the long-term outcomes of patients with MASLD and cirrhosis with and without bariatric surgery.
Methods:
Patients were retrospectively identified from the California Department of Healthcare Access and Information database, 2005 to 2019, for a population-based cohort study. Propensity score matching (PSM) was used to balance background risks between patients with cirrhosis who underwent bariatric surgery and those who did not. Overall, liver-related and non-liver-related mortality were analyzed.
Results:
Of 91,708 eligible patients with MASLD and cirrhosis, PSM yielded 2,107 patients who underwent bariatric surgery and 8,428 non-bariatric controls. Compared to matched controls, patients who underwent bariatric surgery had lower 5-year overall (24.9% vs. 37.1%; p<0.0001), liver-related (3.3% vs. 14%; p<0.0001), and non-liver-related mortality (22.3% vs. 26.9%; p=0.046). In multivariable analysis, bariatric surgery was associated with decreased overall mortality (adjusted hazard ratio [aHR]=0.63; p<0.0001), liver-related (aHR=0.24; p<0.0001), and non-liverrelated (aHR=0.81; p=0.0026) mortality. However, only laparoscopic surgeries were associated with lower overall mortality (aHR=0.39; p<0.0001) whereas open surgeries were associated with higher overall mortality (aHR=1.24; p=0.022).
Conclusions
Patients with MASLD and cirrhosis who underwent bariatric surgery, specifically laparoscopic approaches, had significantly lower mortality risk than non-surgical counterparts.
7.Bioactive metabolites: A clue to the link between MASLD and CKD?
Wen-Ying CHEN ; Jia-Hui ZHANG ; Li-Li CHEN ; Christopher D. BYRNE ; Giovanni TARGHER ; Liang LUO ; Yan NI ; Ming-Hua ZHENG ; Dan-Qin SUN
Clinical and Molecular Hepatology 2025;31(1):56-73
Metabolites produced as intermediaries or end-products of microbial metabolism provide crucial signals for health and diseases, such as metabolic dysfunction-associated steatotic liver disease (MASLD). These metabolites include products of the bacterial metabolism of dietary substrates, modification of host molecules (such as bile acids [BAs], trimethylamine-N-oxide, and short-chain fatty acids), or products directly derived from bacteria. Recent studies have provided new insights into the association between MASLD and the risk of developing chronic kidney disease (CKD). Furthermore, alterations in microbiota composition and metabolite profiles, notably altered BAs, have been described in studies investigating the association between MASLD and the risk of CKD. This narrative review discusses alterations of specific classes of metabolites, BAs, fructose, vitamin D, and microbiota composition that may be implicated in the link between MASLD and CKD.
8.Comparative analysis of household indoor PM2.5 concentrations and prevalence of hypertension between cities
Anujin M ; Myagmarchuluun S ; Erkebulan M ; Ser-Od Kh ; Shatar Sh ; Gantuyаa D ; Enkhjargal G ; Munkh-Erdene L ; Gregory C. Gray ; Jungfeng Zhang ; Damdindorj B ; Ulziimaa D ; Davaalkham D
Mongolian Journal of Health Sciences 2025;89(5):5-10
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.
9.Comparative Analysis of Outdoor Particulate Matter Concentrations in Ulaanbaatar Using Direct Measurements and Fixed Monitoring Station Data
Ulziikhutag B ; Enkhjargal G ; Buyantushig B ; Nyamsuren B ; Shatar Sh ; Gantuya D ; Myagmarchuluun S ; Gregory Gray ; Junfeng Zhang ; Ulziimaa D ; Damdindorj B ; Davaalkham D
Mongolian Journal of Health Sciences 2025;89(5):112-117
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.
10.Comparative Analysis of Outdoor Particulate Matter Concentrations in Ulaanbaatar Using Direct Measurements and Fixed Monitoring Station Data
Maralmaa E ; ; Yerkyebulan M ; Ser-Od Kh ; Shatar Sh ; Gantuya D ; Munkh-Erdene L ; Enkhjargal G ; Myagmarchuluun S ; Gregory Gray ; Junfeng Zhang ; Ulziimaa D ; Damdindorj B ; Davaalkham D ; ; Darambazar G
Mongolian Journal of Health Sciences 2025;89(5):105-111
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.

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