1581 The influence of working hours on depressive symptoms in south korea

Abstract

IntroductionSouth Korea is one of the countries with the longest working hours in the OECD countries. Long working hours can be a risk factor of mental illness as well as cardiovascular disease. The aim of this study was to evaluate the effect of long working hours on depressive symptoms among employees in South Korea.MethodsThis study used data from the Korea Working Conditions Survey in 2014. Study subjects included 22 910 employees aged 19 years or older who work more than 35 hours per week. Working hours were categorised into 35–40, 41–52, 53–68, and more than 68 hours per week. Depressive symptoms were assessed using the WHO’s Well-Being Index with cut-off score of 50. We calculated prevalence ratios of depressive symptoms according to working hours using log-binomial regression.ResultsOnly 38.6% of Korean employees worked 35–40 hours per week. The proportion of employees who worked 41–52, 53–68, and more than 68 hours were 32.7, 15.4, and 4.7%, respectively. The rate of depressive symptoms was 42.8%, and the average of well-being index in Korea was 58.3. The longer the working hours were, the higher the risk of depressive symptoms was. Even after adjusting for sex, age, socioeconomic position, physical problems, job stress and exposure to violence, the risks of depressive symptoms were significantly higher in people who worked 53–68 hours/week (PR, 1.13 95% CI: 1.09 to 1.17), and more than 68 hours/week (PR, 1.07 95% CI: 1.02 to 1.13) than 35–40 hours/week.ConclusionWe showed the long working hours could be an independent risk factor for depressive symptoms in employees. Long working hours can lead to the lack of time to recover and sleep disturbances, which can be associated with depressive symptoms. It is necessary to adjust to the appropriate working hours for employees’ mental health.

Probing the Nanoparticle Loading Characteristics and the Filtration Performance with the Continuous and Intermittent Use of Disposable Filtering Masks

“…Depending on the environmental particulate concentration and inhalation breathing rate, the respirator collects different amounts of particles/aerosol on the filtering media, , leading to a varied extent of performance deterioration. The challenged aerosol/particle mass (μg), which is the total mass of aerosol particles exposed to the filtering mask, can be estimated by eq . In this study, the Korean pollution warning level of PM 10 (particulate matter with size of <10 μm) concentration, 300 μg/m 3 was assumed with two different inhalation flow rates of 30 L/min (stable state) and 85 L/min (intense physical load). ,, The prescribed times for one-time use were 8 and 10 h for NaCl and DOP, respectively . For simulating the exposure condition of 300 μg/m 3 and 8–10 h use time with 85 L/min inhalation, 12.2–15.3 mg particulate mass was continuously loaded at one time, with 24 h intervals.…”

“…For the intermittent exposure (INT), the procedure of particle exposure and storage was repeated until the challenged mass reached up to 200 mg. The amount of challenged particles was determined by the average daily working time of Koreans under intense physical load and high concentration of aerosol. , Then the filtering masks exposed to particles were stored at the three different environmental conditions so that every intermittent exposure was performed at 24 h interval. The storage conditions were (1) 90 °C in a drying oven, (2) 23 °C, 50% RH (ISO 139:2005, standard atmospheres for conditioning and testing), (3) 23 °C and 100% RH.…”

“…Oftentimes, single-use disposable filtering masks are used multiple times for several days after storing the used filtering masks for hours; , in this case, the filtering masks are intermittently exposed to airborne particles and aerosol. Assuming that a user wears a mask in a harsh particulate concentration level of 300 μg/m 3 for 8 h with 85 L/min of inhalation (with intense physical activity), − the filtering mask would be exposed to a total mass of 12.2 mg during that 8 h. The used filtering mask is stored for a while, then reused, being intermittently exposed to particulate matters. With this intermittent and repeated exposure occurring in practical situations for public users, the reusability and recyclability of filtering masks have been vigorously studied. − However, rarely has it been investigated for the effect of intermittent exposure on the filtration performance. − …”