The low heat transfer through firefighters' protective clothing (FPC) to the exterior is thought to be one of the contributing factors to heat stress in firefighters. In order to describe the heat transfer characteristics of FPC, we measured the thermal resistance (TR) of FPC quantitatively by using a movable thermal manikin. To estimate the effect of clothing size on TR, we used M, L, and LL sizes of protective clothing. To simulate the clothing that the firefighters wear at work, we put work clothing (WC) under the FPC, and placed gloves and long boots on the manikin. We also estimated the effect of the length of WC trousers on the overall clothing TR. When the manikin was standing still, the size of the FPC did not affect the overall thermal resistance. When the manikin was walking, however, the LL FPC proved to have less thermal resistance than either the L or M size, presumably because a larger amount of air moved into and out of the LL FPC. When wearing FPC over WC, the larger sizes had a larger TR when standing still. Wearing short trousers under the FPC had little effect on the overall TR and, since wearing long trousers under the FPC was reported to reduce burning on the legs, the change from long trousers to short trousers did not seem to be beneficial.
The use of asbestos gaskets will be prohibited within one year. A variety of non-asbestos sheet gaskets have been developed, but the properties of non-asbestos gaskets at elevated temperatures have not yet been adequately described. In this study, a test method is proposed in which the existing JIS B 2490 "Test method for sealing behavior of gaskets for pipe flanges" is extended to include elevated temperatures. The sealing performance of two kinds of non-asbestos sheet gasket, i.e. the expanded PTFE sheet gasket and the non-asbestos compressed fiber sheet gasket, was evaluated using this new test method and the sealing performance of each non-asbestos sheet gasket at elevated temperatures was clarified. The proposed method proved effective in evaluating the sealing performance of non-asbestos sheet gaskets by testing for leaks at temperatures of over 100°C.
The natural hormone 17beta-estradiol (E2) is considered an endogenous cancer risk factor, and one possible mechanism of carcinogenesis involving E2 is through the induction of oxidative stress. E2 is metabolized to two catecholestrogens, 2-OHE2 and 4-OHE2, by CYP1A1 and CYP1B1, respectively. Both metabolites can contribute to metabolic redox cycling, which induces ROS and causes the formation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG). Since the levels of E2 change in accordance with the menstrual cycle in women, it is important to consider the menstrual cycle when assessing the risk posed to female workers when they are exposed to substances inducing ROS. In the present study, we investigated whether the levels of urinary 8-OH-dG changed during the different phases of the menstrual cycle. The test subjects were all female office workers from the same company. Information on demographic factors, phases of the menstrual cycle , and lifestyle factors were obtained from self-administered questionnaires which were then checked during interviews. Urine specimens were collected in the morning and were used to measure 8-OH-dG, E2, and creatinine levels. The concentrations of 8-OH-dG and E2 were normalized against creatinine content. The test subjects who provided menstrual cycle information (non-smokers who did not take hormone-like medicines) were classified into four groups, depending whether they were in their menstrual phase (n=15), follicular phase (n=35), luteal phase (n=28), or in menopause (n=15). Although the difference was not statistically significant, the urinary 8-OH-dG level of the luteal phase group was higher than that of the menstrual phase group (4.1±0.6 μg/g creatinine and 3.0±0.4μg/g creatinine, respectively). These results suggested that the level of the oxidative state during the luteal phase was higher than that during the menstrual phase.
To ensure worker safety, scaffold structures are regulated under the Industrial Safety and Health Law. To guarantee the strength of the scaffolds, the length of the stiffening member of the main frame must also be regulated by the standard. However, no such regulations exist and little research data is available with respect to the shear rigidity of the flooring ledger frame. It is thought that the shear rigidity of the flooring ledger frame influences the overall resistance of the scaffolds to buckling, but the importance of this phenomenon remains unclear. Based on previous research carried out by the author, this study proposes an equation for evaluating the strength of standard prefabricated scaffolds in which the buckling analysis of these standard prefabricated scaffolds is based on the shear rigidity of the main and flooring ledger frames. The suitability of the proposed evaluation equation is also examined.
Integrated Manufacturing System (IMS) is an automated system that allows multiple machines to be controlled in harmony with each other. Even though we refer to it as an automated system, it is necessary for operators to intervene in IMS for operations such as shift-change, confirmation of operation, trouble shooting, maintenance/ inspection, repair and cleaning. When these operations are carried out, an accident resulting in injury or death might occur as a result of collisions between operators and machines if an inharmonious relationship between operators and machines exists. Thus, IMS needs to be implemented in conjunction with risk reduction methods so that any failure in this relationship can be predicted and also to avoid possible injuries. The objective of this study was to devise processes that would reduce IMS-related risks, Processes to reduce risk need to be considered in relation to the following hazardous conditions. (1) Operators encroach into manufacturing lines a previous machine-related issue. (2) Operators perform incorrect re-start procedures. (3) Multiple operators intrude into a manufacturing line at the same time. (4) Operators' movement across areas of the manufacturing line that are divided up into multiple zones. However, as many hazardous conditions exist, it is difficult to define all of the safety requirements and to implement safety measures. In order to define safety requirements more easily at the system design stage, this paper proposes a method that requires design engineers only fill in four forms, which will be described later. This study also formulated systematic processes to reduce risk in IMS by applying new concepts such as classification of risk management, Classification of the various protection methods and operations carried out under hazardous conditions. Applying the proposed procedure, a building system made up of modules (for which the safety has been demonstrated in advance) will make it easier to verify (certify) safety of the system and will improve productivity when the safety system is implemented. These results will be utilized in a reconsideration of the ISO11161 standard in relation to Integrated Manufacturing Systems (IMS).
Recently, accidents have occurred in waste disposal and recycling facilities. This has led to requests to construct a safety and security system in those facilities. I propose the use of the safety design technique known as SAD (Safety design Analysis with Database) as a new risk assessment technique. We define the risk as the amount of damage. We made the formula of the amount of damage which is composed of the amount of the personal damage and the facilities damage, and the facilities stop damage. We carry out an assessment of the safety level by using SAD. SAD is a technique which combines quantity risk assessment features from both top-down systems such as FTA and bottom-up systems such as FMEA, in conjunction with the information provided by accident, trouble and HIYARIHATTO databases. This paper presents an outline of SAD, as applied to the meltdown & power generation facilities. By adding information on facilities to ATHDB, SAD could quantitatively assess the risk of 137 accident cases. In addition, using the ATM (Accident Tracing Map), each accident case could be clearly described and the safety improvement plan examined.
A new sample preparation method for airborne particulate matter in workplace was studied. The samples were collected on plastic sheets using a cascade impactor. After the collection, each sample loading sheet was then heated to 140°C to bring about thermal shrinkage, thereby concentrating the surface particles. This method was applied to the simulated welding fume samples using XRF and LA-ICP-MS. With both these methods, we obtained signals 2.4 to 7.5 times greater comparing to that without thermal shrinkage.
This study examined the flexion angle of the trunk of the human body when descending stairs hastily. In recent years, the number of accidental falls among the elderly when descending stairs has increased, so urgent measures need to be taken prevent such accidents. This study focused on the flexion motion of the trunk which indicates the state of balance of the body, and examined the mechanism by which such trunk flexion is controlled when descending stairs at different speeds. The subjects in this study were four elderly males and four elderly females. The subjects descended a three-step stair at four speeds (slow, suitable, fast and very fast) while a motion capture system measured their trunk flexion angle. The results showed that as the speed of descent increased, the trunk flexion angle decreased, especially at the second step, when compared with the first step. This occurred because the degree of trunk flexion corresponded to the compensation motion needed to descend the stairs hastily. Due to these factors, trunk flexion was reduced in order to keep the body in balance. The trunk flexion angle of the female subjects decreased significantly more than that of the male subjects. This was due to the lower muscular strength of the female subjects, combined with their higher awareness of danger, so that they were less able to control their body motion. In this study, it was concluded that elderly people need to take greater care when descending stairs, especially on and after the second step.