Background There is a lack of research evidence on the association between sugar-sweetened beverage (SSB) consumption and gestational diabetes mellitus (GDM) in China. Objective To explore the association between frequency of SSB consumption before pregnancy and risk of GDM in pregnant women in Shaanxi Province, and to provide a scientific basis for targeted interventions to control maternal blood glucose. Methods The recruitment to the China Birth Cohort study started in October 2020. Pregnant women at 6-16 weeks who had their first prenatal examination at five hospitals in Shaanxi Province were recruited. A maternal health questionnaire was used to collect basic information about pregnant women. A semi-quantitative food frequency questionnaire was used to collect the consumption of carbonated beverages, fruit and vegetable juice beverages, coffee beverages, and milk tea beverages in one year before pregnancy, which were summed to obtain the SSB consumption. Pregnant women were divided into three groups according to SSB consumption, namely <1 serving·week⁻¹, 1-4 servings·week⁻¹, and ≥5 servings·week⁻¹. GDM was confirmed by oral glucose tolerance test (OGTT) between 24-28 weeks of gestation. A binary logistic regression model was applied to explore the association between SSB consumption and risk of GDM. Multiple linear regression was applied to investigate the associations between SSB consumption (per 1-serving·d⁻¹ increase) and OGTT fasting plasma glucose, 1-hour glucose, and 2-hour glucose. Results A total of 3811 pregnant women were finally enrolled in this study, of which 752 developed GDM, with an incidence rate of 19.7%. The incidence rates of GDM in pregnant women with SSB consumption frequency of <1 serving·week⁻¹, 1-4 servings·week⁻¹, and ≥5 servings·week⁻¹ were 18.0%, 21.1%, and 26.8%, respectively. After adjusting for maternal age, pre-pregnancy body mass index (BMI), education, number of children born, family history of diabetes, smoking, alcohol consumption, physical activity level, and total energy intake, the risk of GDM increased by 26% (OR=1.26, 95%CI: 1.05, 1.50) in the 1-4 servings·week⁻¹ group and by 76% (OR=1.76, 95%CI: 1.31, 2.38) in the ≥5 servings·week⁻¹ group compared to the <1 serving·week⁻¹ SSB consumption group, respectively. Further stratified analysis revealed no interaction effect (P_interaction>0.05) between SSB consumption and maternal age, pre-pregnancy BMI, or first labor or not. For each additional SSB consumption per day, the risk of GDM increased by 94% (OR=1.94, 95%CI: 1.37, 2.75); and the maternal OGTT 1-hour glucose and 2-hour glucose increased by 0.33 mmol·L⁻¹ and 0.18 mmol·L⁻¹, respectively (P<0.05), and no significant increase in fasting plasma glucose was found (P>0.05). Conclusion Higher SSB consumption before pregnancy increases the risk of GDM in pregnant women.

Background Public places are frequently polluted by cigarette smoking, and there is a lack of accurate, real-time, and intelligent monitoring technology to identify smoking behavior. It is necessary to develop a tool to identify cigarette smoking behavior in public places for more efficient control of cigarette smoking and better indoor air quality. Objective To construct a model for recognizing cigarette smoking behavior based on real-time indoor concentrations of PM_2.5 in public places. Methods Real-time indoor PM_2.5 concentrations were measured for at least 7 continuous days in 10 arbitrarily selected places (6 public service providers and and 4 office or other places) from Oct. to Nov. 2022 in Pudong New Area, Shanghai. Indoor nicotine concentrations were monitored with passive samplers simultaneously. Outdoor PM_2.5 concentration data were obtained from three municipal environmental monitoring stations which were nearest to each monitoring point during the same period. Mann-Whitney U test was used to compare indoor and outdoor means of PM_2.5 concentrations, and Spearman rank correlation was used to analyze indoor PM_2.5 and nicotine concentrations. An interactive plot and a random forest model was applied to examine the association between video observation validated indoor smoking behavior and real-time indoor PM_2.5 concentrations in an Internet cafe. Results The average indoor PM_2.5 concentration in the places providing public services [(97.5±149.3) µg·m⁻³] was significantly higher than that in office and other places [(19.8±12.2) µg·m⁻³] (P=0.011). The indoor/outdoor ratio (I/O ratio) of PM_2.5 concentration in the public service providers ranged from 1.1 to 19.0. Furthermore, the indoor PM_2.5 concentrations in the 10 public places were significantly correlated with the nicotine concentrations (r_s=0.969, P<0.001). Among them, the top 3 highly polluted places were Internet cafes, chess and card rooms, and KTV. The results of random forest modeling showed that, for synchronous real-time PM_2.5 concentration, the area under the curve (AUC) was 0.66, while for PM_2.5 concentration at a lag of 4 min after the incidence of smoking behavior, the AUC increased to 0.72. Conclusion The indoor PM_2.5 concentrations in public places are highly correlated with smoking behavior. Based on real-time indoor PM_2.5 monitoring, a preliminary recognition model for smoking behavior is constructed with acceptable accuracy, indicating its potential values applied in smoking control and management in public places.

Background Subways are typical congregate settings and may facilitate aerosol transmission of viruses. However, quantified transmission probability estimates are lacking. Purpose To model spread and diffusion of respiratory aerosols in subways by simulation and calculation of infection probabilities. Methods The internal environment of carriages of Shanghai Metro Line 10 was used to establish a study scene. The movement of tiny particles was simulated using the turbulent model. Trend analysis of infection probabilities and viral quantum doses was conducted in a closed subway carriage scene by a quantum emission-infection probability model. Results Under a typical twelve-vent air conditioning configuration, respiratory droplet aerosols within a subway carriage dispersed rapidly throughout various regions due to airflow, with limited short-term diffusion to other carriages. Concurrently, owing to the uncertainty of airflow patterns, the airflow might circulate and converge within carriages, causing delayed outward dispersion or hindered dispersion of droplet aerosols upon entry into these zones. Passengers boarding the carriage could exacerbate the formation of these zones. When the air conditioning system functioned adequately (air exchange rate=23.21 h⁻¹), the probability of a virus carrier transmitting the virus to other passengers within the same carriage via aerosol transmission was approximately 3.8%. However, in the event of air conditioning system failure (air exchange rate=0.5 h⁻¹), this probability escalated dramatically to 30%. Furthermore, a super-spreader (with virus spreading exceeding 90% of the average) elevated the infection probability to 14.9%. Additionally, due to the complexity of turbulence within the carriage, if local diffusion occurred in 1/2 zones of a carriage, the anticipated infection probability would increase to 8.9%, or during the morning or evening rush hours leading to elevated aerosol concentrations, the infection probability would rise to 4.7%. The subway transmission probability for common coronaviruses diminished to as low as 0.9%. Conclusion Combined computational fluid dynamics and infection probability analysis reveals that in the prevalent twelve-vent air conditioning configurations, despite being a major transportation hub with substantial spatial-temporal overlap, the internal space of subway carriages exhibits a certain level of resistance to virus aerosol transmission owing to built-in ventilation capabilities. However, turbulence and passenger positioning may lead to localized hovering of droplet aerosols, thereby increase the risk of virus transmission. Furthermore, super-spreaders, poor operational status of built-in air conditioning system, and high passenger volume at morning or evening peak hours exert profound effects on virus transmission and infection probability.

Background Aluminum activates signal transducer and activator of transcription 3 (STAT3), causing microglial nucleotide-binding and oligomerization domain-like receptors protein 3 (NLRP3) inflammasome activation and inflammatory responses and producing neurotoxicity. Objective To explore the role of STAT3 regulated NLRP3 inflammasomes in the inflammatory response of mouse microglia cell line (BV2) cells induced by maltol aluminum [Al(mal)₃]. Methods BV2 cells were assigned to five groups: one control group, three Al(mal)₃ exposure groups (low, medium, and high doses at 40, 80, and 160 μmol·L⁻¹ Al(mal)₃ respectively), and one C188-9 (STAT3 antagonist) intervention group [10 μmol·L⁻¹ C188-9 +160 μmol·L⁻¹ Al(mal)₃]. Cell viability was detected by CCK8. The expression of M1/M2 type markers, i.e. CD68/CD206, STAT3, p-STAT3, NLRP3, cleaved-casepase-1, and apoptosis-associated speck-like protein (ASC) in BV2 cells were detected by Western blotting, and proinflammatory cytokines interleukin (IL)-1β and IL-18, and anti-inflammatory cytokine IL-10 were determined by ELISA. Results The results of cell viability assay showed that cell viability gradually decreased with the increase of Al(mal)₃ dose. Compared with the control group, the cell viability of the Al(mal)₃ high-dose group was decreased by 18% (P<0.05); compared with the Al(mal)₃ high-dose group, the cell viability of the C188-9 intervention group was significantly elevated by 14% (P<0.05). Compared with the control group, the expression levels of CD68 in the Al(mal)₃ low-, medium-, and high-dose groups were elevated by 19%, 20%, and 21%, respectively (P<0.05); the expression level of CD206 in the Al(mal)₃ high-dose group was decreased by 25% (P<0.05). Compared with the Al(mal)₃ high-dose group, the expression level of CD68 in the C188-9 intervention group was reduced by 9% (P<0.05), whereas the expression level of CD206 was elevated by 22% (P<0.05). Compared with the control group, the p-STAT3 protein expression and the p-STAT3/STAT3 ratio in the Al(mal)₃ high-dose group increased by 129% and 127%, respectively (P<0.05). Compared with the Al(mal)₃ high-dose group, the p-STAT3 protein expression and the p-STAT3/STAT3 ratio in the C188-9 intervention group were decreased by 55% and 54%, respectively (P>0.05). Compared with the control group, the expression level of NLRP3 protein increased by 75% in the Al(mal)₃ high-dose group (P<0.05), the expression levels of cleaved-casepase-1 protein increased by 28% and 35% in the Al(mal)₃ medium- and high-dose groups (P<0.05), and the expression levels of ASC increased by 22%, 25%, and 53% in the Al(mal)₃ low-, medium- and high-dose groups (P<0.05), respectively. Compared with the Al(mal)₃ high-dose group, the expression levels of NLRP3, cleaved-casepase-1, and ASC proteins in the C188-9 intervention group decreased by 30%, 19%, and 32%, respectively (P<0.05). Compared with the control group, the levels of IL-1β in the Al(mal)₃ medium- and high-dose groups increased by 18% and 21%, respectively (P<0.05), and the level of IL-18 in the Al(mal)₃ high-dose group increased by 10% (P<0.05). Compared with the Al(mal)₃ high-dose group, the IL-18 levels were reduced by 23% in the C188-9 intervention group (P<0.05). The content of anti-inflammatory factor IL-10 did not differ significantly between groups (P>0.05). Conclusion Aluminum can induce inflammatory responses in BV2 microglia and is predominantly pro-inflammatory, and the mechanism may involve STAT3 regulation of NLRP3 inflammasome secretion of inflammatory factors.

Background Osteoclast stimulatory transmembrane protein (OC-STAMP) is involved in silicosis fibrosis induced by silicon oxide (SiO₂) exposure. Its role in silicosis fibrosis by inducing ferroptosis of alveolar type II epithelial cells and its related mechanism remain unclear. Objective To explore the effect and possible mechanism of OC-STAMP on ferroptosis of alveolar type II epithelial cells and silicosis fibrosis in rats under SiO₂ exposure. Methods Twenty male Wistar rats of SPF grade were randomly divided into two groups: control (Sham) group and SiO₂ group, 15 rats in each group. Rats in the SiO₂ group were given 1 mL of 50 mg·L⁻¹ SiO₂ suspension at one time through the non-exposed intratracheal instillation method to establish an animal model of silicosis, and rats in the Sham group were give 1 mL of 0.9% sodium chloride solution in the same way. Rats were sacrificed after 8 weeks. Samples of lung tissue were fixed in glutaraldehyde or paraformaldehyde for observing ultrastructure of mitochondria by transmission electron microscopy; HE, Masson, VG, and Prussian blue were used to observe changes in lung tissue structure and iron deposition. The expression level of OC-STAMP and the degree of lung fibrosis were evaluated by immunohistochemistry and immunofluorescence. The expression level of OC-STAMP in rat lung tissue was detected and the transfection effect of OC-STAMP was verified by real-time fluorescence quantitative polymerase chain reaction (RT-PCR). Overexpression (OCS group) and inhibition expression (SI-OC group) models were constructed by OC-STAMP plasmid and OC-STAMP small interfering RNA (siRNA) transfection to cultured MLE-12 cells, respectively. The relative expression levels of glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11), and other proteins in lung tissue and MLE-12 were detected by Western blotting. Results The results of HE, Masson, and VG staining showed that the silicosis modeling was successful after 8 weeks of SiO₂ exposure. The immunofluorescence results showed that OC-STAMP and ATP binding cassette subfamily A member 3 (ABCA3) co-localized in alveolar type II epithelium. The immunohistochemical results showed that the levels of OC-STAMP and collagen I in the SiO₂ group were significantly higher than those in the Sham group (P<0.01). The RT-PCR results showed that the OC-STAMP mRNA in the lung tissue of the SiO₂ group was significantly higher than that of the Sham group (P<0.01). The Prussian blue staining in the lung tissue of the SiO₂ group showed positive brownish-yellow particles. Compared with the Sham group which showed normal mitochondrial structure, the mitochondrial structure was generally swollen and the mitochondrial cristae dissolved and disappeared in the SiO₂ group by transmission electron microscope observation. The Western blotting results showed that the expression levels of SLC7A11 and GPX4 both decreased in the lung tissue of the SiO₂ group (P<0.05, P<0.01), and the expression level of Vimentin increased (P<0.01). In the transfected MLE-12 cells, compared with the Sham group, the expression levels of SLC7A11 and GPX4 in the OCS group were significantly reduced (P<0.05, P<0.01). Conclusion OC-STAMP may affect the expression of proteins related to ferroptosis, and promote lung fibrosis induced by SiO₂ exposure.

Background Long-term exposure to whole-body vibration (WBV) will affect the health of occupational drivers. However, research on the characteristics of WBV exposure by urban bus drivers and health risk evaluation is still insufficient. Objective To identify the characteristics of occupational WBV exposure of bus drivers serving 31 bus routes provided by three branches of Haikou Public Transport Group, and to evaluate their occupational health risks related to WBV. Methods A total of 31 out of 142 bus routes run by three branches of Haikou Public Transport Group were selected to monitor WBV exposure of 31 bus drivers during driving. WBV parameters such as triaxial frequency weighted acceleration (a_wx, a_wy, a_wz) and triaxial crest factor (CF_x, CF_y, CF_z) of the drivers were determined with a six-channel human vibration meter. Two methods, 8-hour daily value of the weighted root mean square average weighted vibration [A(8)] based on a_w and 8-hour daily value of vibration dose [VDV(8)] based on vibration dose value (VDV), were used for health risk assessment and classified WBV health risk results into three levels (high, medium, and low) by the exposure action value (EAV) and exposure limit values (ELV) for A(8) and VDV(8) recommended by ISO 2631-1:1997. The two evaluation methods, A(8) and VDV(8), were compared by Fisher's exact test. Results Regarding the WBV parameters, the vector sum of acceleration (a_v) was 0.321-0.680 m·s⁻², the VDV of monitoring interval was 3.824-10.174 m·s^−1.75, and the VDV(8) was 6.039-13.505 m·s^−1.75; their values in mean ± standard deviation were (0.480±0.100) m·s⁻², (6.987±2.737) m·s^−1.75, and (9.773±4.540) m·s^−1.75, respectively. Positive correlations were found between a_wx and a_wz, a_v and a_wz, CF_x and CF_y, CF_y and CF_z. No bus route's WBV exposure level was graded as high health risk by either A(8) or VDV(8). The number of routes graded as low health risk by A(8) was 26, while the number by VDV(8) was 12. The consistency rates of health risk levels evaluated by the two methods were 66.7% (6/9), 54.6% (6/11), and 45.5% (5/11) for the three bus group branches, respectively. The difference in WBV health risk assessment results between the two evaluation methods was not statistically significant. Conclusion Positive correlations are found between triaxial acceleration and triaxial crest factor. There is no difference in the results of using A(8) and VDV(8) to evaluate health risks of WBV in urban bus routes.

Background The human body is usually exposed to a variety of heavy metals at the same time, and different types and concentrations of heavy metals may have complex interactions during their absorption and metabolism in the human body. Seminal fructose is an important energy source for sperm movement. A large number of studies have shown that metal exposure may impair semen quality, and seminal fructose is an important factor affecting male reproduction, so it is necessary to investigate the relationship between mixed heavy metal exposure and seminal fructose to explore the mechanism of semen quality damage caused by metal exposure. Objective To understand the status of common heavy metal exposure in men of childbearing age in Puyang City, Henan Province, and to study the relationship between mixed exposure to heavy metals and seminal fructose, as well as potential interactions among heavy metals. Methods Volunteers were recruited from the Puyang Maternal and Child Health Hospital Reproductive Center for a cross-sectional survey on general demographic characteristics, smoking, alcohol consumption, and other information. Semen samples were collected to detect 12 metals such as vanadium (V), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), selenium (Se), silver (Ag), cadmium (Cd), barium (Ba), thallium (Tl), iron (Fe), and lead (Pb) in seminal plasma and seminal fructose. After correcting for selected confounding factors, a Bayesian kernel machine regression (BKMR) model was used to evaluate the impact of seminal plasma heavy metal mixed exposure and its interactions on seminal fructose. Results A total of 825 adult males were enrolled. The concentrations in M (P₂₅, P₇₅) of V, Mn, Co, Ni, Zn, Se, Ag, Cd, Ba, Tl, Fe, and Pb in seminal plasma were 0.39 (0.28, 0.54), 12.31 (8.92, 17.52), 0.26 (0.18, 0.38), 5.15 (3.32, 8.64), 182159.80 (121847.80, 199144.50), 13.61 (10.55, 17.68), 0.03 (0.02, 0.04), 0.34 (0.27, 0.46), 8.64 (5.94, 13.43), 0.06 (0.05, 0.08), 168.74 (114.17, 259.45), and 1.69 (1.15, 2.36) μg·L⁻¹ respectively. The Spearman correlation results indicated that there was a negative correlation between V, Mn, Co, Zn, Se, Ba, Tl, or Fe in seminal plasma and seminal fructose (P<0.05), and the values of r (95%CI) were −0.044 (−0.087, −0.001), −0.129 (−0.171, −0.087), −0.055 (−0.099, −0.012), −0.099 (−0.143, −0.056), −0.053 (−0.097, −0.010), −0.068 (−0.111, −0.025), −0.095 (−0.138, −0.052), and −0.082 (−0.125, −0.039), respectively. The results of multiple linear regression indicated that there was a negative correlation between the exposure level of Cd, Mn, Zn, Ag, Ba, Tl, or Fe in seminal plasma and seminal fructose (P<0.05), the values of associated β (95%CI) were −0.551 (−0.956, −0.147), −0.315 (−0.419, −0.212), −0.187 (−0.272, −0.103), −0.161 (−0.301, −0.021), −0.188 (−0.314, −0.062), −1.159 (−2.170, −0.147), and −0.153 (−0.230, −0.076), respectively. The BKMR model analysis showed that seminal fructose level decreased with the increase of plasma metal mixed exposure concentration. Compared with all metal exposure at P₅₀, the seminal fructose level decreased by 0.2374 units when all metal exposure was at P₇₅. Seminal plasma Zn [posterior inclusion probabilities (PIPs)=1.0000] had the strongest effect on seminal fructose, followed by Mn (PIPs=0.5872), Se (PIPs=0.5656), and Ba (PIPs=0.5398). The univariate exposure-response curve showed a negative approximate linear correlations between Ba or Mn and seminal fructose, a positive linear correlation between Se and seminal fructose, and an approximate inverted U-shaped association between Zn and seminal fructose. No significant interaction between studied metals was found. Conclusion Mixed metal exposure may lead to decrease of seminal fructose, in which Zn, Mn, Se, and Ba may play an important role. Mn and Zn exposure may reduce the level of seminal fructose, Se may increase the level of seminal fructose, and there may be a threshold effect between Zn exposure and seminal fructose level. No interaction between different metals on seminal fructose is found.

Background Occupational pneumoconiosis is the most common occupational disease in Qinghai Province and China. From the perspective of public health, it is important to assess the disease burden using disability-adjusted life years (DALY) and economic losses. Objective To evaluate the disease burden of occupational pneumoconiosis in Qinghai Province, and to provide a basis for the formulation and implementation of relevant prevention and control strategies. Methods Based on the registered data, a database of occupational pneumoconiosis cases confirmed and reported in Qinghai Province was established. The survival status and death dateof occupational pneumoconiosis patients from 2015 to 2019 were confirmed by on-site visit, telephone survey, matching search of Death Information Registration and Management System, and consulting other departments. The life loss due to occupational pneumoconiosis from 2015 to 2019 was assessed using DALY as an indicator and data from the Global Burden of Disease 2019 (GBD 2019) study. Inpatients with officially diagnosed occupational pneumoconiosis from a hospital in Qinghai Province in 2019 were selected as study subjects, the direct economic loss was evaluated with hospitalization expenses, and the indirect economic loss due to occupational pneumoconiosis in Qinghai Province in 2019 was calculated by human capital approach. Results From 2015 to 2019, 505 new cases of occupational pneumoconiosis were reported in Qinghai Province, and there were 348 death cases. Prevalent cases and years lost due to disability (YLD) due to occupational pneumoconiosis were increased, while DALY and years of life lost (YLL) due to occupational pneumoconiosis decreased firstly and then increased. In each year, there were 87% or more of the DALY, YLL, or YLD attributed to silicosis and coal workers' pneumoconiosis. In 2019, the occupational pneumoconiosis-associated DALY was 2173.55 person years. The total hospitalization expense incurred by 42 inpatients with occupational pneumoconiosis was 1256345.19 yuan. The total hospitalization expense and average daily cost of the inpatients with stageⅡand Ⅲ pneumoconiosis were higher than that of the inpatients with stageⅠ (P<0.05), and the hospitalization expense was higher in the ≥60 years age group than in the <60 years age group (P<0.05). In 2019, the indirect economic burden incurred by occupational pneumoconiosis in Qinghai Province was 44108581.65 yuan, and accounted for 0.15‰ of the gross domestic product (GDP) of the province. Conclusion The disease burden associated with occupational pneumoconiosis in Qinghai Province are outstanding. Silicosis and coal workers' pneumoconiosis are the key contributors. Targeted intervention measures including dust hazard control, enterprise management, follow-up and rehabilitation management of pneumoconiosis should be taken to prevent and control the occurrence and progression of pneumoconiosis and alleviate disease burden of pneumoconiosis.

Background The safety of drinking water is closely related to people's health. In recent years, relevant studies have identified some health related problems with drinking water in Inner Mongolia Autonomous Region. The complex and diverse natural environment embraced by the vast jurisdiction of the region may lead to uneven drinking water quality across the region. Objective To evaluate eight chemicals including arsenic, cadmium, chromium (hexavalent), lead, mercury, fluoride, trichloromethane, and carbon tetrachloride in urban drinking water in Inner Mongolia Autonomous Region in 2021, and to provide reference for optimizing urban water supply system and ideas for further developing strategies to promote population health. Methods A total of 1228 monitoring sites were set up in urban areas of Inner Mongolia, and water samples were collected once in dry season (May) and once in wet season (August−September). Eight chemicals of interest in drinking water were detected according to the Standard examination methods for drinking water, and assessed for health risks using the health risk assessment model recommended by the United States Environmental Protection Agency (USEPA) and following the Technical guide for environmental health risk assessment of chemical exposure. Mann-Whitney U test was used to compare the concentrations of eight chemicals in urban drinking water by water seasons and water sample types. Results In 2021, a total of 2381 samples of urban drinking water were tested in the Inner Mongolia Autonomous Region, including 1195 samples in wet season and 1186 samples in dry season; 389 samples of finished water and 1992 samples of tap water. The positive rates of arsenic and fluoride were 26.25% and 96.77%, respectively. The positive rates of cadmium, chromium (hexavalent), lead, mercury, trichloromethane, and carbon tetrachloride were 6.22%, 16.63%, 6.09%, 16.67%, 18.98%, and 8.36%, respectively. The exceeding standard rate of fluoride was 4.87%. Trichloromethane and carbon tetrachloride were qualified in all samples. There were statistical differences in the concentrations of arsenic, cadmium, chromium (hexavalent), lead, and carbon tetrachloride in urban drinking water between water seasons (Z=−3.847, P<0.05; Z=2.464, P=0.014; Z=−3.129, P=0.002; Z=4.341, P<0.05; Z=4.342, P<0.05). Only fluoride concentration was found statistically different among different water sample types (Z=−2.287, P=0.022). The non-carcinogenic risks of ingestion and dermal exposure to each chemical in drinking water by water seasons and water sample types were all less than 1, but the P₉₅ total non-carcinogenic risks of oral exposure were greater than 1. The P₉₅ carcinogenic risks of oral exposure to some chemicals in drinking water by water seasons and water sample types were>10⁻⁴, which suggested carcinogenic risks, while the carcinogenic risks of dermal explore to chemicals were all less than 10⁻⁶. Conclusion In 2021, urban drinking water in Inner Mongolia Autonomous Region is generally safe, but arsenic, cadmium, chromium (hexavalent), lead, mercury, and fluoride still exceed the national limits, posing certain health risks.

Background Most metro system are underground, airtight, with inadequate ventilation and massive gatherings, posing health risks to metro riders. Objective To evaluate air quality of Metro Line 1 in a city, and provide suggestions and basis for preventing harmful factors and protecting the health of passengers. Methods Station halls, station platforms, and metro carriages of Metro Line 1 in a city were monitored in summer (from July to August in 2021) and winter (from January to February in 2022). Six metro stations were selected by stratified sampling. Each station and carriage were monitored for three consecutive days in rush hours (9:00–11:00 and 19:00–21:00) and non-rush hours (11:00–13:00), with the same monitoring frequency. The monitored indicators were physical factors (temperature, relative humidity, wind speed, illumination, and noise), chemical factors (carbon monoxide, carbon dioxide, inhalable particles, formaldehyde, benzene, toluene, xylene, ammonia, and ozone), biological factor (airborne total bacterial count), and radiation factor (radon). The monitoring results were compared by location, time period, and season. Results According to the Hygienic indicators and limits for public places (GB 37488—2019), the selected physical factors did not meet the standard, especially the temperature and relative humidity of station hall and platform, and wind speed and noise of carriage. The results of physical factors varied significantly by location (P<0.05). In summer, the temperature of carriage [M (P₂₅, P₇₅), 23.9 (23.3, 24.6)℃] was the lowest, and the wind speed [0.78 (0.37, 1.11) m·s⁻¹] and noise [76.0 (72.0, 80.3) dB] of carriage were the highest; in winter, the temperatures of station hall and platform were the lowest [16.2 (13.2, 17.2)℃ and 16.2 (13.4, 17.0)℃, respectively], the relative humidity of carriage [26.4% (24.2%, 27.9%)] was the lowest, and the wind speed and noise of carriage were the highest [0.83 (0.47, 1.18) m·s⁻¹ and 74.5 (70.1, 78.3) dB, respectively]. The physical factors varied significantly by time period (P<0.05). In summer, the temperature was the lowest during morning rush hours [24.0 (23.0, 24.8)℃] and non-rush hours [24.2 (23.2, 24.9)℃], and the relative humidity during evening rush hours was the lowest [41.9% (37.0%, 47.8%)]; in winter, the temperature was the lowest during morning and evening rush hours [16.8 (13.4, 19.7)℃ and 16.5 (15.1, 19.4)℃, respectively], the relative humidity during the non-rush period was the lowest [26.8% (24.7%, 28.6%)], and the wind speed during evening rush hours was the highest [0.28 (0.19, 0.51) m·s⁻¹]. All measured chemical factors, biological factor, and radiation factor met the national standard (GB 37488—2019). Conclusion The chemical, biological, and radiative factors are complied with the national standard (GB 37488—2019) except physical factors such as temperature, relative humidity, wind speed, and noise. We suggest that the metro operators make full use of air conditioning system in combination with humidifiers to better regulate temperature and relative humidity, and .arrange working hours reasonably and provide noise-proof earplugs for carriage staff to protect against noise hazard.