Association Between Flexible Work Arrangement and Sleep Problems Among Paid Workers: Using 6th Korean Working Conditions Survey.

Background: As social distancing persists and interest in work-life balance grows, more companies are adopting flexible work policies. While there have been studies on sleep disorders associated with different types of work, such as shift work, research exploring the relationship between flexible work schedules and sleep disorders is still limited, particularly among Korean workers. Methods: We performed a secondary analysis of the 6th Korean Working Conditions Survey, focusing on 31,243 paid workers out of a total of 50,538 participants. We defined flexible workers as those who set their own working hours. Sleep disorders were divided into three categories: 'difficulty falling asleep,' 'frequent waking during sleep,' and 'waking up feeling exhausted and fatigued.' Using scores derived from three specific symptoms, the Minimal Insomnia Symptoms Scale (MISS) was calculated to assess the prevalence of insomnia. We used chi-square tests to analyze demographic and job-related differences. A multivariate logistic regression analysis was employed to identify any relationship between flexible work schedules and sleep disorders. Results: Significant differences were found between flexible and non-flexible workers regarding age, income level, education level, and job type. Flexible workers reported sleep-related symptoms significantly more often. The odds ratio for insomnia was 1.40 (95% CI 1.21-1.61). For males, the odds ratio was 1.68 (1.36-2.08). Conclusion: This study establishes a correlation between flexible work schedules and sleep disorders among Korean salaried workers. Potential causes could include changes in circadian rhythm, increased work demands, and extended working hours. To precisely determine causality and associated diseases, further research is required.

Beyond working hours: the association between long working hours, the use of work-related communication devices outside regular working hours, and anxiety symptoms.

OBJECTIVES: The present study aimed to identify and compare the associations between long working hours and use of work-related communication devices outside regular working hours and anxiety symptoms, thereby providing insight into redefining working hours. METHODS: Based on the cross-sectional data from the sixth Korean Working Conditions Survey (KWCS), specifically the responses from 46 055 workers, the use of work-related communication devices outside of regular working hours, long working hours, and anxiety symptoms were assessed. To investigate the associations between using work-related communication devices outside regular working hours or long working hours with anxiety symptoms, odds ratios (ORs) and 95% CIs were calculated using multiple logistic regression models. RESULTS: Among 46 055 participants, 25 659 (55.7%) used work-related communication devices outside working hours, 8145 (17.7%) worked long hours, and 2664 (5.8%) experienced anxiety symptoms. Compared with the reference group, those who used work-related communication devices outside regular working hours without working long hours, had higher OR of anxiety symptoms (OR: 2.18; 95% CI, 1.97-2.41) than those who worked long hours without using work-related communication devices during off-hours (OR: 1.32; 95% CI, 1.09-1.59). Furthermore, the group that both worked long hours and used work-related communication devices outside working hours exhibited the highest OR of anxiety symptoms (OR: 2.57; 95% CI, 2.24-2.97). CONCLUSIONS: Using work-related communication devices outside regular working hours is associated with a higher risk of anxiety symptoms compared with long working hours. This result suggests that using work-related devices outside regular working hours, in addition to regular work time, should be considered when redefining working hours.

Association between lone work and self-rated health status: using the 5th Korean Working Conditions Survey.

Background: Lone workers are generally defined as individuals who work alone without supervision, including self-employed people. While lone workers are considered a vulnerable group in some countries, there is a lack of research on their health status in domestic studies. Globally, the number of lone workers has been increasing, and this trend has been further accelerated since the coronavirus disease 2019 (COVID-19) pandemic with the rise of remote work. Methods: The study analyzed data from 44,281 participants, excluding unpaid family workers, soldiers, and those with missing data. Lone workers were defined as individuals who reported having no colleagues with the same job at their current workplace. Self-rated health status was categorized as "good" or "poor." Results: This study found a statistically significant higher number of lone workers among women compare to men. The largest occupational category for lone workers was service and sales workers, followed by agriculture and fisheries workers. A majority of non-lone workers reported working 40 hours or less per week, while the majority of lone workers reported working 53 hours or more per week. In addition, lone workers had significantly poorer health status evaluations compared to non-lone workers (odds ratio: 1.297; 95% confidence interval: 1.165-1.444). Conclusions: Further research is needed to investigate the causal relationship between lone work and health, using data collected after the COVID-19 pandemic.

Cancer risk in Vietnam war veterans from the Korean Vietnam war veterans' health study cohort.

Introduction: During the Vietnam War, several unknown chemicals, such as Agent Orange, were used in Vietnam by the military. Therefore, there have been continuous health concerns among the Vietnamese population and veterans exposed to these hazardous chemicals. This study aimed to investigate the risk of all cancers and also organ-specific cancers among Korean veterans of the Vietnam War. Methods: This study used a national representative cohort that included all Korean Vietnam War veterans as the interest group, with 1:4 age-sex-region-matched general Korean citizens as the reference group, from 2002 to 2018. Age-standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated for all cancers and for 31 organ-specific cancer categories based on the medical facility visit data. Results: An increased SIR of 1.07 (95% CI, 1.06-1.08) was observed for all cancers among the veterans. There was a significantly increased risk of cancer among 22/31 organspecific cancers, with 18 cancer categories showing a significantly higher risk than all cancers. The highest risk was observed for "malignant neoplasms of other parts of the central nervous system" (SIR, 1.71; 95% CI, 1.51-1.92). Discussion: This study evaluated the risk of cancer among Korean Vietnam War veterans. Further studies are warranted to investigate various health determinants in the veterans as well as the Vietnamese population.

Standards for recognition and approval rate of occupational cerebro-cardiovascular diseases in Korea.

Background: Although working hours have decreased in Korea, they are still high compared to that of other countries. In Korea, cardiovascular and cerebrovascular diseases (CCVDs) related to overwork in Korea continually occur, and the social burden from overwork is estimated to be high. This study investigated the amendment of regulations affecting the approval rate of occupational CCVDs. Methods: The change in approval rate of occupational CCVDs and related regulations were investigated using the Act and public notice on the standards for recognition of occupational CCVDs and the yearbooks of the Ministry of Employment and Labor. The CCVD mortality was estimated using data on the number of deaths according to the cause of death, the number of employed people, and resident registration population aged 15-64 years. The cumulative mortality of CCVDs was estimated using the Kaplan-Meier method. Results: Since the establishment of the standards for recognition in Korea in 1982, the scope of occupational diseases has been expanded to include intracerebral hemorrhage, subarachnoid hemorrhage, cerebral infarction, myocardial infarction, and aortic dissection. In 2013, the concept of working hours was introduced in chronic overwork. The approval rate of occupational CCVDs was 44.7% in 2006, which decreased to 12.9% in 2011. After the improvement of related regulations, the approval rate increased to 41.3% in 2018. From 2000 to 2017, the CCVD mortality of both the unemployed and employed tended to decrease, and their cumulative CCVD mortalities were 549.3 and 319.7 per 100,000 people, respectively. Conclusions: CCVDs are recognized as occupational diseases in Korea. The amendments to the standards for recognition, the introduction of the Occupational Disease Adjudication Committee, the principle of presumption, and the reduction of working hours have changed the approval rate of occupational CCVDs. A strategic approach is needed to further reduce the incidence of CCVDs.

Cohort Profile: Gachon Regional Occupational Cohort Study (GROCS).

Background/Aims: The Gachon Regional Occupational Cohort Study (GROCS) is a large-scale longitudinal study of occupational safety and health data (covering Work Environment Monitoring, Workers' Health Surveillance, and Occupational Health Service) conducted by the Gachon University Gil Medical Center (GUGMC) in Incheon, Republic of Korea. We conducted GROCS to identify the health effects of workers' occupational risks, behavior, socioeconomic status, and life style. Methods: The GROCS includes data from Work Environment Monitoring, Workers' Health Surveillance, and Occupational Health Service. The baseline year for all data collection was 2018. Work Environment Monitoring was conducted in 240 companies located in Incheon. General Health Examination and Special Health Examination were performed on 32,725 and 9,504 workers, respectively. Occupational Health Services were provided to 16,883 workers in 171 companies. These data have been collected and operated at an external data management institution and were provided as a retrospective cohort after removing personal identification information. Results: In 2018, the total number of companies was 2,854, among which which 488 special Health Examination, 171 Work Environment Monitoring, and 240 Occupational Health Service. The proportion of companies undergoing Special Health Examination was 17.1%, the proportion of companies undergoing Work Environment Monitoring was 8.4%, and the proportion of Companies undergoing Occupational Health Service was 6.0%. Conclusion: GROCS expects researchers to utilize its useful and reliable resource for occupational health and surveillance with for academic or political purposes to lead to improved workers' health and working environment.

Associations between Awareness of the Risk of Exposure to Pollutants Occurring at Fire Scenes and Health Beliefs among Metropolitan Firefighters in the Republic of Korea.

Firefighters are repeatedly exposed to various pollutants that occur at fire scenes. There are three levels of exposure: primary exposure to pollutants, secondary exposure to pollutants on personal protective equipment (PPE), and tertiary exposure to contaminated fire stations and fire engines due to pollutants on PPE. Therefore, it is important for firefighters to be aware of the risk of exposure to pollutants and to practice health behaviors such as appropriate PPE management. No clear association has been established in the existing literature between firefighters' risk perception level and their health beliefs about the health impact of awareness of exposure to hazardous substances at fire scenes. This study aims to evaluate the relationship between awareness of the exposure risk to primary, secondary, and tertiary pollutants and health beliefs. It was designed as a cross-sectional study, in which a web-based survey was conducted from 13 May to 31 May 2021. The analysis was conducted in 1940 firefighters working in the Seoul metropolis who agreed to participate in the research. Participants who perceived susceptibility were likely to be aware of the primary (adjusted odds ratio (AOR) = 2.10, 95% confidence interval (CI) 1.16-3.80), secondary (AOR = 2.77, 95% CI 1.77-4.32), and tertiary (AOR = 2.73, 95% CI 1.85-4.03) exposure risks. Participants who perceived barriers were unlikely to be aware of the risk of exposure to primary (AOR = 0.67, 95% CI 0.49-0.91), secondary (AOR = 0.77, 95% CI 0.61-0.96), and tertiary (AOR = 0.75, 95% CI 0.62-0.91) pollutants. Educational intervention is recommended to improve perceived susceptibility and awareness of the risk of exposure to pollutants and reduce perceived barriers. Consequently, educational intervention is expected to positively impact firefighters' management of appropriate PPE. We confirmed an association between occupational exposure risk and firefighters' health beliefs. In the health belief model (HBM), health beliefs that affect health behavior also affect awareness of the exposure risk level. Therefore, an intervention for health beliefs can also be used to raise job-related exposure risk awareness. Regular training on the health impacts of fire scenes is necessary for both newcomers and incumbents to enable firefighters to better recognize the risks of each occupational exposure level. Additionally, laws and regulations are necessary for the removal of harmful substances that contaminate PPE, such as self-contained breathing apparatus (SCBA), during exposure to a fire scene. Our research can be used as a basis for improving fire policies and education programs in the future.

Analysis of self-reported mental health problems among the self-employed compared with paid workers in the Republic of Korea.

Background: As self-employed workers are vulnerable to health problems, this study aimed to analyze mental health problems and sleep disturbances among self-employed workers compared with paid workers in Korea. Methods: A total of 34,750 workers (23,938 paid workers and 10,812 self-employed workers) were analyzed from the fifth Korean Working Condition Survey, which included 50,205 households collected by stratified sampling in 2017. To compare mental health problems and sleep disturbance among self-employed workers and paid workers, multivariate logistic regression analyses were performed. Results: The odds ratio in self-employed workers compared with paid workers was 1.25 (95% confidence interval [CI]: 1.09-1.42) for anxiety, 1.11 (95% CI: 1.04-1.17) for overall fatigue, 1.11 (95% CI: 1.04-1.20) for difficulty falling asleep, 1.10 (95% CI: 1.02-1.18) for difficulty maintaining sleep and 1.24 (95% CI: 1.16-1.32) for extreme fatigue after waking up. Conclusions: Self-employed workers in Korea have a higher risk of self-reported mental health problems and sleep disturbances than paid workers. Further studies with a longitudinal design and structured evaluation are required to investigate the causal relationship between health problems and self-employment.

Cohort Profile: The Korean Vietnam War Veterans' Health Study Cohort (KOVECO).

During the Vietnam War, many troops and citizen were exposed to large amounts of Agent Orange (AO), and the hazardous effects of AO are continuously being researched and reported. The Korean Vietnam War Veterans' Health Study Cohort (KOVECO) is a retrospective cohort to demonstrate the health status of the Korean Vietnam War veterans and their second-generation offsprings. The KOVECO is a collaboration of data from the Ministry of Patriots and Veterans Affairs and the National Health Insurance Sharing Service from 2002 to 2018. The study participants were all Korean Vietnam War veterans and their second-generation offsprings, and the references were the general population in which gender and region were matched with the participants. As of 2002, 191,272 Vietnam War veterans (1,000,320 comparisons) and 1,963,402 s-generations (1,173,061 references) were included in the cohort. The KOVECO consists of personal information, medical facility visit information, and general health examination information. The KOVECO could act as a health surveillance system, which would be able to detect long-term health effects caused by exposure to AO and provide a direction for policy making through academic research.

Examination of Factors Influencing SCBA Washing Behavior among Firefighters in Metropolitan.

Field-washing decontamination of equipment is an effective way for firefighters to reduce their risk of secondary contamination. No study has yet clarified the factors influencing effective field decontamination of equipment such as self-contained breathing apparatuses (SCBAs). This study sought to examine factors that influence the SCBA washing and decontamination behavior of firefighters. We conducted a questionnaire using the web-based Seoul Metropolitan Electronic Questionnaire System. As of May 2021, the survey had been sent to 3626 of 7198 Seoul career firefighters, and 1940 subjects were selected to participate in the study. Binomial logistic regression and χ2-test analyses were performed. We confirmed that previous training in SCBA washing was an important factor in effective field decontamination of SCBAs. Firefighters should be trained to perform field decontamination procedures systematically and regulations to perform field decontamination before leaving the scene of a fire should be introduced.

Heat exposure and workers' health: a systematic review.

OBJECTIVES: Several studies on the health effects of heat exposure on workers have been reported; however, only few studies have summarized the overall and systematic health effects of heat exposure on workers. This study aims to review the scientific reports on the health status of workers exposed to high temperatures in the workplace. METHODS: We reviewed literature from databases such as PubMed and Google Scholar, using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines to identify studies that address health effects of heat exposure among workers. RESULTS: In total, 459 articles were identified, and finally, 47 articles were selected. Various health effects of heat exposure on workers have been reported, such as heat-related diseases, deaths, accidents or injuries, effects on the urinary system, reproductive system, and on the psychological system. CONCLUSIONS: Our review suggests that many workers are vulnerable to heat exposure, and this has a health effect on workers.

Association between occupational or environmental noise exposure and renal function among middle-aged and older Korean adults: a cross-sectional study.

Exposure to occupational and environmental noise is closely linked to various auditory system diseases. Few studies have focused on the effect of noise exposure on the extra auditory system, especially the urinary system. We analyzed 17,154 participants aged 40-79 years from the Korea National Health and Nutrition Examination Survey between 2013 and 2018. A self-reported questionnaire was used to assess occupational or environmental noise exposure. Logistic regression was used to determine the differences in the prevalence of chronic kidney disease (CKD) based on noise exposure characteristics. For participants with noise exposure, linear regression was performed to determine relationship of the noise exposure period and estimated glomerular filtration rate (eGFR). In the noise exposure group, a higher CKD prevalence was associated with females who experienced long-term occupational noise (≥ 240 months) (adjusted OR 2.72, 95% CI 1.11-6.66). An increase of one month of occupational noise exposure was associated with a 0.0106 mL/min/1.73 m2 decrease in eGFR in females aged < 60 years. Overall, noise exposure may be a risk factor for reduced renal function, especially long-term occupational noise exposure. More precise studies should determine (1) the relationship between noise and renal function and (2) the underlying mechanisms.

Sunlight exposure and eye disorders in an economically active population: data from the KNHANES 2008-2012.

BACKGROUND: Sunlight exposure is a major risk factor for eye disorders. Most outdoor workers cannot avoid sunlight exposure. This study aimed to analyze the relationship between outdoor sunlight exposure and eye disorders in an economically active population. METHODS: This study analyzed the 2008-2012 Korea National Health and Nutritional Examination Survey data. Sunlight exposure was categorized as < 5 hours and > 5 hours. We also analyzed the dose-dependent relationship between exposure to sunlight and eye disorders (cataracts, pterygium, and age-related macular degeneration [AMD]) using data from 2010 to 2012 by subdividing the exposure groups into < 2 hours, 2-5 hours, and ≥ 5 hours. Eye disorders were diagnosed by an ophthalmologist. The study participants were stratified by sex, and the results were analyzed using the χ2 test and multiple logistic regression analysis. RESULTS: In the female group, the odds ratio of pterygium in the high-level sunlight exposure group was 1.47 (95% confidence interval [CI]: 1.15-1.89). Regarding AMD, the odds ratios were 1.42 (95% CI: 1.16-1.73), 1.33 (95% CI: 1.03-1.73), and 1.58 (95% CI: 1.15-2.16) in the total, male, and female groups, respectively. Analysis of the dose-response relationship revealed that the odds ratios of pterygium in the high-level sunlight exposure subgroups of the total and female groups were 1.62 (95% CI: 1.25-2.08) and 2.00 (95% CI: 1.39-2.88), respectively. CONCLUSIONS: This study demonstrated a relationship between sunlight exposure and eye disorders in an economically active population. Women were found to be especially vulnerable to pterygium. However, additional prospective studies to clarify the pathophysiology of pterygium are needed.

Associations of Abnormal Sleep Duration with Occupational and Leisure-time Physical Activity in the Working Population: A Nation-wide Population-based Study.

BACKGROUND: The present study investigated the association between two domains of physical activity (occupational physical activity [OPA] and leisure-time physical activity [LTPA]) and sleep duration. METHODS: We investigated 3,421 paid workers from the Korea National Health and Nutrition Examination Survey, 2014-2015. Sleep duration was categorized into three categories (short for less than 5 h, optimal for 5-9 h, and long for more than 9 h). OPA and LTPA were defined in terms of answers to relevant questions. Odds ratios were calculated for sleep duration according to each physical activity domain using multinomial logistic regression models. RESULTS: There were 464 subjects (13.6%) who showed short sleep duration, and 169 subjects (4.9%) who showed long sleep duration. Prevalence of OPA and LTPA was higher in male workers than in female workers (for OPA: 3.67% and 1.76%, respectively, p = 0.0108; for LTPA: 16.14% and 6.07%, respectively, p < 0.0001). The odds ratio of OPA for long sleep duration in female workers was 3.35 (95% confidence interval, 1.37-8.21). Otherwise, LTPA was not associated with sleep duration in female paid workers, nor both physical activity domains in male paid workers. CONCLUSION: Female paid workers with work-related physical activity were at risk of oversleeping. These findings also suggested that physical activity has distinct associations with sleep duration according to the physical activity domains and sex.

Effects of work organization on the occurrence and resolution of sleep disturbances among night shift workers: a longitudinal observational study.

This study aimed to investigate the association between work organization and the trajectories of insomnia patterns among night shift workers in a hospital. The health examination data of hospital workers, recorded from January 2014 to December 2018, were collected; 6765 records of 2615 night shift workers were included. Insomnia was defined as a score of ≥ 15 on the Insomnia Severity Index (ISI). Participants were categorized into five groups according to insomnia patterns derived from the analysis of their ISI scores. Work organization and socio-demographic characteristics were also investigated. Generalized estimating equation models and linear mixed models were constructed to analyze the longitudinal data. Of the total participants, 53.0% reported insomnia at least once during the follow-up period. The lack of nap opportunities and work-time control was associated with the occurrence of insomnia, whereas more than 5 years of shift work experience was related to the resolution of insomnia. All work-related factors were significantly related to insomnia risk; however, the effects were not significant in the sustained insomnia group. Although sleep problems are inevitable in night shift workers, well-designed work schedules and better work organization can help reduce the occurrence of insomnia among them.

Association between breakfast skipping and metabolic outcomes by sex, age, and work status stratification.

BACKGROUND: The association between breakfast skipping and abnormal metabolic outcomes remains controversial. A comprehensive study with various stratified data is required. OBJECTIVE: The aim of this study was to investigate the relationship between abnormal metabolic outcomes and breakfast skipping by sex, age, and work status stratification. METHODS: We used data from the Korea National Health and Nutrition Examination Surveys from 2013 to 2018. A total of 21,193 (9022 men and 12,171 women) participants were included in the final analysis. The risk of metabolic outcomes linked to breakfast skipping was estimated using the negative binomial regression analysis by sex, work status, and age stratification. RESULTS: A total of 11,952 (56.4%) participants consumed breakfast regularly. The prevalence of abnormal metabolic outcomes was higher among those with irregular breakfast consumption habits. Among young male workers, negative binomial regression analysis showed that irregular breakfast eaters had a higher risk of abnormal metabolic outcomes, after adjusting for covariates (odds ratio, 1.15; 95% confidence interval, 1.03-1.27). CONCLUSIONS: The risk of abnormal metabolic outcomes was significant in young men in the working population. Further studies are required to understand the association of specific working conditions (working hours or shift work) with breakfast intake status and the risk of metabolic diseases.

Working Conditions and Mental Health Status Related With Occupational Injury of Korean Outdoor Workers.

OBJECTIVE: This study investigated the working conditions and mental health status linked to occupational injury among Korean outdoor workers. METHODS: Socioeconomic and occupational characteristics were collected using self-reported questionnaires from 26,468 paid workers selected using the 5th Korean Working Conditions Survey. The relationships among mental health issues, occupational injury, and working outdoors were estimated by logistic regression. RESULTS: Outdoor workers were relatively older with lower educational levels and income, worked longer, and had greater exposure to occupational hazards, higher occupational injury rate, significantly higher risk of sleep disturbances, and higher occupational injury rates due to sleep disturbances than non-outdoor workers. CONCLUSIONS: There was a significant relationship among working outdoors, sleep quality, and mental health-related issues due to exposure to occupational hazards. Specific occupational health and safety strategies are needed to protect the mental health of outdoor workers.

Chronic Cadmium Intoxication and Renal Injury Among Workers of a Small-scale Silver Soldering Company.

BACKGROUND: Cadmium exposure may induce chronic intoxication with renal damage. Silver soldering may be a source of cadmium exposure. METHODS: We analyzed working environment measurement data and periodic health screening data from a small-scale silver soldering company with ten workers. Concentrations of cadmium in air from working environment measurement data were obtained. Concentrations of blood and urinary cadmium, urine protein, and urine ß2-microglobulin (ß2M) were obtained. The generalized linear model was used to identify the association between blood and urine cadmium and urine ß2M concentrations. Clinical features of chronic cadmium intoxication focused with toxicological renal effects were described. RESULTS: The mean duration of work was 8.5 years (standard deviation [SD] = 6.9, range = 3-20 years). Cadmium concentrations in air were ranged from 0.006 to 0.015 mg/m3. Blood cadmium concentration was elevated in all ten workers, with a highest level of 34.6 µg/L (mean = 21.288 µg/L, SD = 11.304, range = 9.641-34.630 µg/L). Urinary cadmium concentration was elevated in nine workers, with a highest level of 62.9 µg/g Cr (mean = 22.151 µg/g creatinine, SD = 19.889, range = 3.228-62.971 µg/g creatinine). Urine ß2M concentration was elevated in three workers. Urinary cadmium concentration was positively associated with urine protein concentration (beta coefficient = 10.27, 95% confidence interval = [4.36, 16.18]). Other clinical parameters were compatible with renal tubular damage. CONCLUSION: Cadmium intoxication may occur at quite low air concentrations. Exposure limit may be needed to be lowered.

Prevention of exposure to and spread of COVID-19 using air purifiers: challenges and concerns.

Coronavirus disease 2019 (COVID-19) is now a pandemic. The Korean government has declared a red alert, which is the highest level of the national infectious disease alert system, and the World Health Organization has similarly declared its highest-level pandemic alert (phase 6). The spread of COVID-19 is an unprecedented worldwide public health problem that governments and individuals must work to overcome. Recently, an infection cluster arose in a call center in Seoul. To support call center companies, the Korean Ministry of Employment and Labor has proposed covering the costs of installing partitions and air purifiers, providing hand sanitizers, and supplying masks to prevent droplet and aerosol infections. Air purifiers are expected to be installed on the floor with the exhaust outlets at a higher level, such as the level of the desks or breathing zones of workers. When a worker coughs or releases droplets near a colleague's respiratory system, the droplets may spread throughout the call center via air flow from air purifier. In this fashion, a single infected person can give rise to an infection cluster. Attempts to prevent infection must not lead to new infections, and the installation of air purifiers may cause new problems. Therefore, using air purifiers to control the spread of COVID-19 should be approached with caution.

Association between Working Hours and Self-Rated Health.

This study compared the association between working hours and self-rated health (SRH) according to sex, socioeconomic status, and working conditions. In all, 25,144 participants were selected from the Korea National Health and Nutrition Examination Survey (KNHANES), conducted from 2010 to 2018. The risks of poor SRH, according to working hours, were investigated using multiple logistic regression. Both short and long working hours were associated with poor SRH. Men working short hours and women working long hours were at risk of poor SRH. Workers with fewer than nine years of education were at risk of poor SRH when working short hours, whereas workers with more than nine years of education were at risk when working long hours. Similarly, simple laborers were at risk of poor SRH when working short hours, while managers and professional workers were at risk when working long hours. When working for short hours, paid employees were at risk of poor SRH. Workers with a non-fixed work schedule showed no risk of poor SRH when working long or short hours. In conclusion, workers working short hours with low education and workers working long hours with high education were at risk of poor SRH. Working conditions were significantly related to the association between SRH and working hours.