In recent years, workplace harassment has been attracting attention in Japan and abroad as a factor behind workers’ mental health problems. This paper examines the impact of workplace harassment on workers’ mental health using panel data of employer-employee matching data for small and medium-sized firms in Hyogo Prefecture. In the analysis, we compare the impacts of workplace harassment on mental health with that of various stressors associated with mental health. We also examine the effects of workplace harassment on the intention to quit the firm and the actual separation. The results show the negative relationship between workplace harassment and workers’ mental health. The negative impact of harassment on mental health is of non-negligible magnitude, comparable to the negative effect of about 70 hours of unpaid overtime work per month on mental health. Furthermore, results show that workplace harassment increases workers’ intention to quit the firm. These results suggest that workplace harassment has a significant impact on workers’ mental health and has no small impact on a firms’ human resource management.

Since the flash points of petroleum-based solvents, which are multi-component industrial products, can change as the evaporation progresses, it is difficult to predict the flash point accurately. In this study, petroleum-based solvents (petroleum ether, white gasoline, benzine, lacquer thinner, paint thinner) were selected as samples and investigated a method for predicting the flash point. Evaporated samples with mass loss fractions of 0, 0.1, 0.2 and 0.3 were prepared by weathering the solvents. We calculated the component compositions from the area percentage of the peaks of the total ion chromatogram obtained by GC/MS analysis and found out the changes in the composition of petroleumbased solvents with the progress of evaporation. Vapor pressure constants were derived from the saturated vapor pressure measurements of the evaporated samples and a calculation method for the saturated vapor pressure at an arbitrary temperature and mass loss fraction was presented. We assumed that vapor concentration at flash point is equal to lower explosion limit and predicted the flash point of evaporated samples by using the component composition obtained by GC/MS analysis and the calculation method for the saturated vapor pressure. The flash points predicted by the proposed method were almost in agreement with the measured values.

In the current study, we investigated the effect of prolonged exposure to various work-related adverse events on workers’ mental health. Thirty-six events were selected as targeted events from the list of national occupational compensation insurance of Japan.

A web-based follow-up study was conducted on Japanese workers. All participants provided their demographic data and personal experience on 36 events in the past year. Their occupational stress was assessed by a self-administered questionnaire on occupational stress widely used in the Japanese Stress Check Program. Data from 3,071 participants were finally analyzed. Logistic regression analysis with high stress judged by the Japanese Stress Check Program as outcome and experience patterns regarding long-term exposure to each event as the independent variable were conducted.

The concentration of work to a person and great variability in job-demand showed a high relationship between occupational stress especially when one has continuously been exposed to it. Human relations and excessive workload were also found related to workers’ stress; however, their effects of continuous exposure did not reach statistical significance. Our study found the work-related events that may show a greater negative effect when exposed for a longer period, and events that require quick intervention. These findings are expected to lead to appropriate labor management in the future.

When an exterior wall of a small-scale building was demolished, a fall-down method using manual labor is applied. In the method, tensile materials such as wire ropes are placed on the exterior wall to prevent the wall from collapsing in the outward direction. Next, the wall is divided into sections, and the lower section of the wall is manually weakened by the worker; then, the wall is pulled down using the tensile material. However, it is possible that the wall falls during the manual weakening of the lower section of the wall, leading to accidents and casualties. One of the accident cases is considered to be the excessive tension of the tensile material. In this study, the relationship between tension and sagging in the tensile material have been examined by experiments. After that, the fall displacement of the wall to outside of the building was examined, and the appropriate tension of the tensile material was examined. The results indicated that the tensile material must be slightly loosened when the workers are still working inside or in the vicinity of the building. Moreover, when the wall is pulled down using the tensile material, the lower section of the wall gets damaged due to buckling of the reinforcing bar and crushing of the concrete. This study also examined how the tension of the tensile material gets transmitted to the lower section of the wall. The results highlighted that the tension of the tensile material is directly proportional to the force applied to the lower section of the wall.

SWire rope is one of the main components in mechanical structures such as cranes and elevators. During hoisting and lowering of a load, the rope moves along the sheaves under tension and is subjected to bending loads. This repetitive bending load causes the wires to gradually break, leading to rope rupture. Furthermore, IWRC ropes which have become the mainstream rope for cranes in recent years had clarified that wire breakage occur preferentially inside the rope. Therefore, it is necessary to establish a method for detecting wire breakage inside the rope and to elucidate the breakage mechanism. However, since ropes are composed of multiple twisted wires, it is difficult to identify the position of wire breakages in the rope cross-section. In this study, the positions of wire breakages in rope cross-section were evaluated applying a recently proposed estimation method. The subject ropes were prepared by S-bending fatigue test. The results of wire breakage distribution in a rope cross-section revealed that there were conditions under which wires were prone to breakage, depending on the sheave contact area and the positional relationship with adjacent wires. In addition, the mechanism of visible wire breakage and its relationship with the current disposal standards were discussed.

A thermal lag in reaction calorimeters could cause an underestimation of the rate of heat generation. Therefore, investigating the correction method used to estimate the thermal lag is essential. In general, a controlled heat source and time constants are the variable parameters used to estimate the correction. This paper reports an improved correction method for estimating the thermal lag in reaction calorimeters using heat pulses and higher-order time constants. It was observed that thermal lags occurred when the sample vessels containing water were exposed to heat pulses. Our studies revealed that the accuracy of the correction improved with an increase in the order of time constants. The effect of the position of the heat source on the higher-order time constants was determined. It was observed that the heat sources, when located outside the sample vessels, contributed to the underestimation of the heat generation rate due to the lack of correction of thermal lags in the sample vessel. For heat generation by the dissolution of sodium hydroxide, changing the position of the heat source yielded widely different heat generation rates, thereby proving that a suboptimal placement of the heat source led to an underestimation of thermal hazards.

Nowadays, electrostatic theories are usefully applied to various industries. However, incidents could be caused by electrostatic discharge in manufacturing industries, such as fire and explosion disasters in chemical industries. Therefore, it is very important to develop electrostatic control products. In order to quantitatively evaluate the electrostatic hazards, a numerical analysis method based on plasma discharge theory is required. In this work we present an evaluation approach for electrical insulation using Townsend theory and streamer theory of breakdown in gases. The particle tracking method is used for air dielectric breakdown at atmospheric pressure. By this method, the Townsend ionization coefficient is integrated along the lines of electric field and the integrated values are compared with the threshold criterion of dielectric breakdown. As a result, the dielectric breakdown of the air gaps between rod-plate and plate-plate electrodes are evaluated. Furthermore, the validity of the particle tracking method for evaluating electrical insulation is verified.

Previous studies on spray electrification have shown that the amount of charging strongly depends on the combination of the liquid type and nozzle material. To prevent accidents, understanding, in advance, the charging hazards of each combination of liquid type and nozzle material, avoiding combinations that increase the charging, and taking sufficient safety measures according to the charging hazards are necessary. Predicting the hazard from the combination of liquid type and nozzle material is difficult with conventional knowledge. In this study, we proposed a simple method to evaluate the risk of spray electrification for various combinations and investigated the usefulness of the proposed method by measuring the charge for eight different liquids and three different materials. Consequently, clear differences were observed in the measured charges for each combination, and the charging characteristics shown in this study were in agreement with those in previous findings on spray electrification. Furthermore, except for certain combinations, the measured values obtained in this study were equal to or higher than those in the previous studies. Therefore, the proposed method reproduces spray electrification and is useful for hazard assessment.

This study aimed to explore the background of traumatic events and possible preventive measures among health care workers. We analyzed data from 84 compensated health care workers who experienced traumatic events between 2010 and 2017. We found that about half of the workers had encountered violence, and nearly half were alone at the time of the violence event. In addition, the victims were not helped by colleagues at the time of the violence event because their colleagues could not help them quickly enough. The assailants most likely experienced symptoms from dementia or mental illness, which contributed to the traumatic events. However, in the majority of cases, any underlying disease or symptoms the assailants who caused the traumatic events might have experienced had not been recognized. In addition, the particular complaints of the assailants, such as “I want to go home,” might have been background factors that contributed to the events. In order to create a safe workplace where health care workers can provide high quality care, it is necessary to enhance the mental health care system and train health care workers in and increase their knowledge about preventing violence. Moreover, it is also critical to establish a system that encourages the application of this knowledge in the workplace.

The 13th Workplace Accident Prevention Plan, formulated by the Ministry of Health, Labour and Welfare (MHLW), covers the five-year period from 2018 to 2023 and aims to reduce workplace accidents and create a safe and healthy workplace. The 13th Plan has a target of reducing fatalities by at least 15% by 2022, especially in the forestry industry. The serious occupational accidents occur not only in the forestry industry but also in primary industries including agriculture and fisheries.

The authors have been conducting research to develop measures to prevent such occupational accidents as part of the MHLW Science Research Grant (Comprehensive Research Project on Occupational Safety and Health) 「Research on Formulation of Measures to Prevent Occupational Accidents in the Agricultural, Forestry and Fisheries Industries in Accordance with the Characteristics of the Accidents(H30-Roudou-Ippan-006)」from FY 2018 to FY 2020. In this paper, we introduce our efforts. We collected case studies from various business entities, agricultural cooperatives and other organizations, and government agencies, extracted good and bad practices from the case studies, and proceeded with studies to propose preventive measures and model projects for occupational injuries and health disorders, including cooperation among administrative organizations, industry, government, and academia. Model projects were formulated for each type of business in the primary industry. In addition, it was suggested that continuous awarenessraising can be achieved if support in terms of human resources, material supplies, and useful information can be obtained from all related parties.

The purpose of this study was to clarify the information disclosure on occupational health and safety activities in micro-, small-, and medium-sized enterprises (MSMEs). We surveyed 2,437 companies. Approximately half of these companies were certified as excellent corporations for health management in 2020 (MSME category). We searched the websites of each company and obtained data on information disclosure regarding four survey items: corporate social responsibility, excellent health management, occupational accident prevention measures, and social contribution. We calculated the percentage of companies that made their websites available to the public and disclosed information for each survey item by industry and employee size. In total, 91% companies had publicly available websites. Among all surveyed companies, the proportion of disclosing information was 12% for corporate social responsibility, 56% for excellent health management, 11% for occupational accident prevention, and 18% for social contribution. The proportion of companies disclosing information about occupational accident prevention measures was highest in the transportation industry (79%). With increased employee size, the proportion of companies disclosing information increased for all survey items. It is important to collect and disseminate good examples of companies that are actively engaged in information disclosure.

The notification stipulates “management controllers (MCs)”. However, since the appointment status of these MCs are not clear, no reports examine whether they have been appointed in the companies or not. A questionnaire survey was conducted with the aim of clarifying their appointment status, focusing on the “MCs in charge of respiratory protective equipment”, “ones in charge of vibration tools”, and “ones in charge of chemical substances.” Among 323 companies responded to it, 205 ones that had harmful works. Among them, 199 companies needed to appoint the “MCs in charge of respiratory protective equipment” and 46 did them. Fifty-six companies needed to appoint the “MCs in charge of vibration tool”, and 19 did them. One hundred seventy-nine companies needed to appoint the “MCs in charge of chemical substances”, and 52 did them. The MCs were appointed from the work chiefs in 40% of the companies. As to the reasons why MCs had not been appointed, “general health and safety managers performed such duties” in 62 companies. Only 30 % of the companies appointed MCs. It is suggested that the MCs appointment should be reviewed so that MCs can carry out their duties better in such companies.

Japan’s Ministry of Health, Labour, and Welfare publishes data that lists the occurrence of occupational accidents, etc., in Excel format. The Excel data are not particularly machine-readable, and various problems can occur when processing, editing, and analyzing the data using computer programs such as natural language processing technology. Therefore, I investigated machine-readability issues using the “Standardized Rules for a Machine-Readable Data Format in Statistical Tables” provided by the Ministry of Internal Affairs and Communications. In addition, I identified the problem of typographical errors and notational fluctuations in formatted data items. Based on these issues, I made the following recommendations: (1) utilize database systems to prevent errors from occurring and (2) publish the data in a semi-structured data format that can be described in text files.