Resilience and Depressive Symptoms among Medical Staff in a Military Hospital Dedicated to the Treatment of COVID-19.

Coronavirus disease 2019 (COVID-19) is prevalent around the world, and many studies suggest that depression among medical staff is on the rise during the pandemic. This study aims to assess the relationship between depressive symptoms and individual resilience among military hospital personnel responsible for treating patients with COVID-19. Individuals from the Armed Forces Daejeon Hospital who responded to the questionnaires from 8 February to 15 February 2022 participated in this study. Resilience and depressive symptoms were measured via the Korean Resilience Quotient Test-53 and Patient Health Questionnaire-9, respectively. We employed multivariable logistic regression analysis to estimate Odds Ratios (ORs) and 95% Confidence Intervals (CIs) of depressive symptoms. Among 181 participants, the individuals with depressive symptoms and high resilience accounted for 8.8% and 61.9%, respectively. Significant correlations between depressive symptoms and both the low resilience and low resilience positivity groups were found (adjusted OR 10.30 [95% CI 1.74-61.01] and OR 13.90 [95% CI 1.93-100.02], respectively). This study notes a significant inverse relationship between depressive symptoms and resilience even after adjusting for demographic and occupational characteristics. To overcome depressive symptoms among hospital personnel, it is necessary to seek ways to improve individual resilience, especially positivity.

The risk of occupational injury increased according to severity of noise exposure after controlling for occupational environment status in Korea.

OBJECTIVES: The aim of this study was to examine the relationship between noise exposure and risk of occupational injury. MATERIALS AND METHODS: Korean National Health and Nutrition Examination Survey was used for the current study. Self-report questionnaires were used to investigate occupational injury and exposure to noise, chemicals, and machines and equipments. RESULTS: In separate analyses for occupation and occupational hazard, the proportion of occupational injuries increased according to severity of noise exposure (all P < 0.05). Compared to the non-exposure group, the respective odds ratio (95% confidence intervals) for occupational injury was 1.39 (1.07-1.80) and 1.67 (1.13-2.46) in the mild and severe noise exposure groups, after controlling for age, gender, sleep hours, work schedule (shift work), and exposure status to hazardous chemicals and hazardous machines and equipments. CONCLUSIONS: The current study highlights the association between noise exposure and risk of occupational injury. Furthermore, risk of occupational injury increased according to severity of noise exposure.

The Association Between Blood Mercury Levels and Risk for Overweight in a General Adult Population: Results from the Korean National Health and Nutrition Examination Survey.

The primary objective of this study was to estimate the association between blood mercury levels and overweight in Korean adults. We analyzed cross-sectional data from 9228 participants (4283 men and 4945 women) who completed the Korean National Health and Nutrition Examination Survey (KNHANES), 2007-2013. The population was divided into two groups according to the body mass index (BMI) and waist circumference (WC). Blood mercury levels were analyzed using a gold amalgam method with a DMA-80 instrument, categorized into quartiles, and stratified by sex. After adjusting for all covariates, blood mercury was significantly associated with overweight in all subjects. According to the BMI criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.75 (95 % confidence interval [CI], 1.53-2.01) overall, 2.09 (95 % CI, 1.71-2.55) in men, and 1.58 (95 % CI, 1.32-1.89) in women. According to the WC criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.85 (95 % CI, 1.49-2.30) in men and 1.96 (95 % CI, 1.62-2.36) in women compared to the lowest quartile. Additionally, a trend in overweight across increasing blood mercury levels was observed by the p for trend test in the multiple diagnostic criteria.

Dose - response relationship between noise exposure and the risk of occupational injury.

Many workers worldwide experience fatality and disability caused by occupational injuries. This study examined the relationship between noise exposure and occupational injuries at factories in Korea. A total of 1790 factories located in northern Gyeonggi Province, Korea was evaluated. The time-weighted average levels of dust and noise exposure were taken from Workplace Exposure Assessment data. Apart occupational injuries, sports events, traffic accidents, and other accidents occurring outside workplaces were excluded. The incidences of occupational injury in each factory were calculated by data from the Korea Workers' Compensation and Welfare Services. Workplaces were classified according to the incidence of any occupational injuries (incident or nonincident workplaces, respectively). Workplace dust exposure was classified as <1 or ≥ 1 mg/m³ , and noise exposure as <80, 80-89, or >90 dB. Workplaces with high noise exposure were significantly associated with being incident workplaces, whereas workplaces with high dust exposure were not. The odds ratios (95% confidence intervals) derived from a logistic regression model were 1.68 (1.27-2.24) and 3.42 (2.26-5.17) at 80-89 dB and ≥ 90 dB versus <80 dB. These associations remained significant when in a separate analysis according to high or low dust exposure level. Noise exposure increases the risk of occupational injury in the workplace. Furthermore, the risk of occupational injury increases with noise exposure level in a dose-response relationship. Therefore, strategies for reducing noise exposure level are required to decrease the risk of occupational injury.

Effects of ethanol and phenobarbital on hemoglobin adducts formation in rats exposed to benzidine and Direct Black 38.

The objective of this study was to evaluate the effects of pretreatment of ethanol (EtOH) and phenobarbital (PB), which are known to affect the metabolism of xenobiotics, in the formation of hemoglobin adducts in rats administered with benzidine (BZ) and Direct Black 38 (DB38). The experimental rats were divided into BZ and DB38 groups; each group was subdivided into control, EtOH, and PB groups. Blood samples were separated into hemoglobin and plasma immediately after obtaining and basic hydrolysis was done to convert the adducts into aromatic amines. Hydrolyzed BZ, monoacetylbenzidine (MABZ), and 4-aminobiphenyl (4ABP) were separated by reversed-phase liquid chromatography without derivatization. Then, quantitative analyses were performed using a high performance liquid chromatograph equipped with an electrochemical detector. The amount of metabolites was expressed in the hemoglobin binding index (HBI). As a result, the formations of hemoglobin in BZ-, MABZ-, and 4ABP-HBI of BZ-EtOH and BZ-PB groups were increased compared with those of BZ-control group. In DB38 group, all of HBIs except for BZ-HBI were increased more than those of DB38-control group regardless of the pretreatment. These results are attributable to the fact that EtOH and PB induced N-hydroxylation is related to the formation of hemoglobin adducts. They indicate that EtOH not only increases the adduct formation by inducing N-hydroxylation but also induces N-acetylation. PB induced N-hydroxylation and increased the adduct formation in BZ group, but decreased the adduct formation in DB38 group due to decreasing azo reduction. These results suggest that the effects of EtOH or PB should be considered in biochemical monitoring of BZ and DB38 for the assessment of intermittent exposure to BZ and DB38.

Assessment of Korean farmer's exposure level to dust in pig buildings.

The purpose of the study was to assess Korean farmer's exposure level to dust in pig buildings and dust emissions by investigating airborne concentrations of total and respirable dust. Five main types of pig buildings operating currently in Korea were selected. For area air sampling, 30 sites per each building type were visited during spring (March-May) and autumn (September-November) seasons. For personal air sampling, concentrations of total and respirable dust were measured for 2-3 hours, during cleaning the pig building before the end of the daily shift, by attaching air sampling equipment near to the farmer's breathing zone. Measurement were taken for 8 hours, e.g. average daily work time (09:00-17:00), at 0.5 m above the floor at three locations on the central alley in the pig building. Emission rates of total and respirable dust were estimated by multiplying the mean concentration of total and respirable dust measured near the air outlet by the mean ventilation rate, and expressed either per area or per pig of live weight. The ranges of farmer's exposure level to total dust and respirable dust in the pig buildings were estimated as 0.6-6.7 mg m(-3) and 0.3-3.5 mg m(-3), respectively. The pig buildings operated with a deep-litter bed system showed the highest dust level while the naturally ventilated pig buildings with slats represented the lowest dust level (p<0.05). Emission rates ranged from 35-400 mg h(-1) m(-2) for total dust and from 4-40 mg h(-1) m(-2) for respirable dust, respectively, indicating a similar pattern for the distribution of exposure level. Korean farmers' exposure level to dust in all the pig buildings investigated was below the exposure limit value equal in Korea equal to 10 mg m(-3), while it exceeded the threshold limit values (TLVs) established in other developed countries. In comparison with previous studies performed in other countries, mean exposure level in the pig buildings of Korea was generally lower for total dust and higher for respirable dust based on the area sampling method.

Odor reduction rate in the confinement pig building by spraying various additives.

The objective of this on-site experiment was to evaluate and compare the effectiveness of currently utilized various additives, i.e. tap water, salt water, digested manure, microbial additive, soybean oil, artificial spice and essential oil, to reduce odor emissions from the confinement pig building. Odor reduction rates were evaluated with respect to sensual odor (odor concentration index, odor intensity and odor offensiveness) and odorous compounds (ammonia and sulfuric odorous compounds). Of the additives investigated in this study, salt water, artificial spice and essential oil had a positive effect on reducing odor generation. The effectiveness of salt water was only observed on ammonia, showing the reduction rates as a function of time (t=immediately, 1h, 3h, 5h, and 24h after spraying) were 0.1%, 20%, 36%, 11% and 0.2% as compared to initial level before spraying. The odor intensity and offensiveness were lessened by spraying artificial spice and essential oil of which maximum reduction rates ranged from 60% to 80%. Additionally, the essential oil had a significant effect on reducing sulfuric odorous compounds for 24h after spraying, which implicates that it functioned as not only a masking agent but also as an antimicrobial agent.

Effect of manual feeding on the level of farmer's exposure to airborne contaminants in the confinement nursery pig house.

The objective of the study is to demonstrate an effect of manual feeding on the level of farmer's exposure to airborne contaminants in the confinement nursery pig house. The levels of all the airborne contaminants besides respirable dust, total airborne fungi and ammonia were significantly higher in the treated nursery pig house with feeding than the control nursery pig house without feeding. Although there is no significant difference in respirable dust and total airborne fungi between the treatment and the control, their concentrations in the treated nursery pig house were also higher than the control nursery pig house. The result that the level of ammonia in the treated nursery pig house is lower than the control nursery pig house would be reasoned by the mechanism of ammonia generation in the pig house and adsorption property of ammonia to dust particles. In conclusion, manual feeding by farmer increased the exposure level of airborne contaminants compared to no feeding activity.

Spatial distribution of particulate matter (PM10 and PM2.5) in Seoul Metropolitan Subway stations.

The aims of this study are to examine the concentrations of PM10 and PM2.5 in areas within the Seoul Metropolitan Subway network and to provide fundamental data in order to protect respiratory health of subway workers and passengers from air pollutants. A total of 22 subway stations located on lines 1-4 were selected based on subway official's guidance. At these stations both subway worker areas (station offices, rest areas, ticket offices and driver compartments) and passengers areas (station precincts, subway carriages and platforms) were the sites used for measuring the levels of PM. The mean concentrations of PM10 and PM2.5 were relatively higher on platforms, inside subway carriages and in driver compartments than in the other areas monitored. The levels of PM10 and PM2.5 for station precincts and platforms exceeded the 24-h acceptable threshold limits of 150 microg/m3 for PM10 and 35 microg/m3 for PM2.5, which are regulated by the U.S. Environmental Protection Agency (EPA). However, levels measured in station and ticket offices fell below the respective threshold. The mean PM10 and PM2.5 concentrations on platforms located underground were significantly higher than those at ground level (p<0.05).

Effect of ventilation rate on gradient of aerial contaminants in the confinement pig building.

The principal aim of this study was to compare the aerial contaminants concentrations between the levels of ventilation rate and determine the variation pattern of aerial contaminants affected by the ventilation rate. As a result, there was not significant difference in total dust and total airborne microorganisms among three levels of ventilation rate (P>0.05) whereas the increased ventilation rate lowered the levels of respirable dust and gaseous compounds (P<0.05). Based on the results, it was concluded that the suspended gases in the confinement pig building generally followed the air streamline formed by the ventilation whereas the ventilation rate had little effect on the gradient of particulates, especially total dust, due to gravity generated by their size and weight. The findings that the concentrations of total airborne microorganisms were not also significantly different among the ventilation rates could be explained in terms of the fact that airborne microorganisms are easily adsorbed on the surface of dust particle.

Influence of extreme seasons on airborne pollutant levels in a pig-confinement building.

Understanding airborne pollutant levels in a pig-confinement building in seasons with extreme weather (ie, summer and winter) is important for managing air quality, which affects the health of farmers and others in the neighboring environment. The authors evaluated airborne pollutants-total dust, total airborne bacteria, and total airborne gram-negative bacteria-which had higher concentrations in summer than in winter, and concentrations of respirable dust, gaseous pollutants, and total airborne fungi, which were lower in summer than in winter. The authors found significant differences between summer and winter measurements for respirable dust and gaseous pollutants (p < .05). Total dust was positively correlated with bioaerosols and ammonia (p < .05), whereas respirable dust was positively correlated with odor concentration index (p < .05) and hydrogen sulfide (p < .01).

Symptoms of PTSD according to individual and work environment characteristics of Korean railroad drivers with experience of person-under-train accidents.

OBJECTIVE: The purpose of this study is to collect basic data on the prevalence pattern of posttraumatic stress disorder (PTSD) in Korean railroad drivers exposed to person-under-train accidents according to the individual and working environmental characteristics. METHODS: Questionnaires were sent to all the railroad drivers accompanying active service now by company post. A total of 639 of the 800 questionnaires sent out were returned, showing a response rate of 79.9%. The Impact of Event Scale was utilized to address psychological status of railroad drivers after exposure to person-under-train accident. RESULTS: Score of PTSD, intrusion, and avoidance ranged from 9.6 to 13.2, from 4.2 to 6.1, and from 5.4 to 7.2 according to individual characteristics and ranged from 11.44 to 12.70, from 5.03 to 5.67, and from 6.41 to 7.04 according to working environmental characteristics, respectively. CONCLUSION: This study demonstrated that Korean railroad drivers who experienced person-under-train accident expressed adverse symptoms physically and psychologically more than those who did not experience it. Apart from effect of train driver's age, a wide range of individual and working environmental factors appear to have no association with the level of posttraumatic distress following a person-under-train accident.

[Distribution of airborne fungi, particulate matter and carbon dioxide in Seoul metropolitan subway stations].

OBJECTIVES: The aims of this study were to examine the level of airborne fungi and environmental factors in Seoul metropolitan subway stations and to provide fundamental data to protect the health of subway workers and passengers. METHODS: The field survey was performed from November in 2004 to February in 2005. A total 22 subway stations located at Seoul subway lines 1-4 were randomly selected. The measurement points were subway workers' activity areas (station office, bedroom, ticket office and driver's seat) and the passengers' activity areas (station precincts, inside train and platform). Air sampling for collecting airborne fungi was carried out using a one-stage cascade impactor. The PM and CO2 were measured using an electronic direct recorder and detecting tube, respectively. RESULTS: In the activity areas of the subway workers and passengers, the mean concentrations of airborne fungi were relatively higher in the workers' bedroom and station precinct whereas the concentration of particulate matter, PM10 and PM2.5, were relatively higher in the platform, inside the train and driver's seat than in the other activity areas. There was no significant difference in the concentration of airborne fungi between the underground and ground activity areas of the subway. The mean PM10 and PM2.5 concentration in the platform located at underground was significantly higher than that of the ground (p<0.05). CONCLUSIONS: The levels of airborne fungi in the Seoul subway line 1-4 were not serious enough to cause respiratory disease in subway workers and passengers. This indicates that there is little correlation between airborne fungi and particulate matter.

[Field study of concentrations and emissions of particulate contaminants by types of swine houses in Korea].

OBJECTIVES: Particulate contaminants, such as total and respirable dusts, can harm the health of farm workers via several routes. The principal aims of this field study were to determine the concentrations and emissions of particulate contaminants: total and respirable dusts, in the different types of swine houses used in Korea, and allow objective comparison between Korea and the other countries in terms of swine housing types. METHODS: The swine houses investigated in this research were selected with respect to three criteria: the manure removal system, ventilation mode and growth stage of pigs. Measurements of total and respirable dust concentrations and emissions in the swine houses were carried out on 5 housing types at 15 different farm sites per housing type. The swine houses investigated were randomly selected from farms situated within the central districts in Korea: province of Kyung-gi, Chung-buk and Chung-nam. RESULTS: The total and respirable dust concentrations in the swine houses averaged 1.88 and 0.64 mg/m3, ranging from 0.53 to 4.37 mg/m3 and from 0.18 to 1.68 mg/m3, respectively. The highest concentrations of total and respirable dusts were found in the swine houses with deep-litter bed systems: 2.94 mg/m3 and 1.14 mg/m3, while the lowest concentrations were found in the naturally ventilated buildings with slats: 0.83 mg/m3 and 0.24 mg/m3, respectively (p<0,05). All the swine houses investigated did not exceed the threshold limit values (TLVs) for total (10 mg/m3) and respirable (2.5 mg/m3) dusts. The mean emissions of total and respirable dusts, per pig (75 kg in terms of live weight) and area (m2), from the swine houses were 97.33 and 9.55 mg/h/pig and 37.14 and 12.83 mg/h/ m2, respectively. The swine houses with deep-litter bed systems showed the highest emissions of total and respirable dusts (p<0.05). However, the emissions of total and respirable dusts from the other swine houses were not significantly different (p>0.05). CONCLUSION: The concentrations and emissions of total and respirable dusts were relatively higher in the swine houses managed with deep-litter bed systems and ventilated naturally of the different swine housing types tested. In further research, more farms than the number used in this research should be investigated, which will present objective and accurate data on the concentrations and emissions of total and respirable dusts in Korean swine houses. In addition, personal sampling should be performed to objectively assess the exposure level of farm workers to particulate contaminants.