Industrial lighting covers a wide range of different characteristics of working interiors and work tasks. This study investigated the effects of illumination on visual workload in visual display terminal (VDT) workstation. Ten college students (5 males and 5 females) were recruited as participants to perform VDT signal detection tasks. A randomized block design was utilized with four light colors (red, blue, green and white), two ambient illumination levels (20 lux and 340 lux), with the subject as the block. The dependent variables were the change of critical fusion frequency (CFF), visual acuity, reaction time of targets detection, error rates, and rating scores in a subjective questionnaire. The study results showed that both visual acuity and the subjective visual fatigue were significantly affected by the color of light. The illumination had significant effect on CFF threshold change and reaction time. Subjects prefer to perform VDT task under blue and white lights than green and red. Based on these findings, the study discusses and suggests ways of color lighting and ambient illumination to promote operators' visual performance and prevent visual fatigue effectively.
A survey of taxi drivers was conducted to determine the actual situation of drivers' low back pain (LBP). The survey was carried out in October 2002, the target drivers were asked to complete a questionnaire which contains questions regarding physique of drivers, demographic features, working conditions, office environment, health conditions, the presence of low back pain, the level of low back pain based on Visual Analogue Scale and Roland-Morris Disability Questionnaire score. As a result, the total number of valid responses was 1,334 and the response rate was 71 percent, and the 1-wk prevalence of LBP was 20.5 percent of respondents. Regarding 275 subjects with LBP, Visual Analogue Scale (VAS) averaged 4.3. There was a positive weak correlation between VAS and Roland-Morris Disability Questionnaire score (R=0.41). And Logistic regression analysis was performed to examine the relationship between LBP and occupational factors, the results suggested following items as risk factors; such as history of LBP, suffering from fatigue, diseases other than LBP and smoking habit.
The purpose of this research was to establish a scale for comfort with regard to hand-arm vibration using the category judgment method and to validate the frequency-weighting method of the ISO 5349-1 standard. Experiments were conducted using random signals as stimuli. These stimuli consisted of three types of signal, namely designated stimulus F, with flat power spectrum density (PSD) ranging from 1 to 1,000 Hz, stimulus H with PSD which became 20 dB higher at 1,000 Hz than at 1 Hz, and stimulus L that had a PSD 20 dB lower at 1,000 Hz. These stimuli were selected from the specific spectrum patterns of hand-held vibration tools. These signals were modified by the Wh frequency weighting in accordance with ISO 5349-1, and the R.M.S. values were adjusted to be equal. In addition, the signal levels were varied over a range of five steps to create 15 kinds of individual stimuli. The subjects sat in front of a vibrator and grasped the mounted handle which exposed them to vertical vibrations after which they were asked to choose a numerical category to best indicate their perceived level of comfort (or otherwise) during each stimulus. From the experimental results of the category judgment method, the relationship between the psychological values and the frequency-weighted R.M.S. acceleration according to the ISO 5349-1 standard was obtained. It was found that the subjective response scaling of hand-arm vibration can be used for design-objective values of hand-held tool vibration.
Although much research has been devoted to constructing specific models or to measuring the response characteristics of seated subjects, investigations on a mathematical human model on a seat with a backrest to evaluate vehicular riding comfort have not yet attracted the same level of attention. For the responses of a seated body to vertical vibrations, mathematical models of the mechanisms must be at least two-dimensional in the sagittal plane. In describing the motions of a seated body, two multibody models representative of the automotive postures found in the literature were investigated, one with and the other without a backrest support. Both models were modified to suitably represent the different automotive postures with and without backrest supports, and validated by various experimental data from the published literature pertaining to the same postural conditions. On the basis of the analytical study and the experimental validation, the fourteen-degrees-of-freedom model proposed in this research was found to be best fitted to the test results; therefore, this model is recommended for studying the biodynamic responses of a seated human body exposed to vertical vibrations in various automotive postures.
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.
Fine particle quartz is considered as a lung carcinogen and therefore its monitoring in the workplace is currently required by government legislation across the world. In order to enforce the health and safety standards, techniques that can accurately determine the amounts airborne quartz are necessary. Currently, two techniques dominate quartz analysis the infrared (IR) spectrophotometric analysis and the X-ray diffraction (XRD) method. Unfortunately, there are limitations associated with both techniques in terms of their analysis accuracy and this article discusses both these methods. The study showed that typical quarry quartz samples have a broad particle size distribution where up to 20% of the finer particles in the bulk sample material contain significant amounts of muscovite, kaolinite, rutile and others. This implies that quarry silica particles with a mean diameter of less than 5 μm contain significant amounts of other materials that are not quartz, and hence, would significantly influence the quantification of the particle composition analysis on filter papers used for air monitoring work places. The results of the study suggest that analysis of the fine fraction of a manufactured sample in a particular work environment should be considered as a reference standard for the quantification of the amount of airborne fine particulates an employee could be exposed to. The study also showed that the IR method is more sensitive and less subjective to sample preparation than the XRD method of analysis.
Chemical industries being the seat of dangerous occurrences frequently resulting in injuries, an occupational injury surveillance study was initiated involving 307 permanent and 419 temporary workers in a chemical company to understand the contribution of different possible factors on injury causation. Risk calculation was undertaken in relation to every individual factor using univariate and multivariate analysis techniques. Workers of lower age were found to be more susceptible to accidents (as evidenced by negative correlation coefficient), though non-significantly. Lower job duration (experience) had a significant impact on injury causation (correlation coefficient -0.5115, p<0.05). Alcohol habit could not show any significant impact but smoking/chewing habit showed significant effect (OR, 7.29: 95% CI, 3.88-9.33) on accident occurrence. Nature of job had no significant impact but nature of employment was found to have considerable effect on the causation of injuries. Temporary nature of employment was at greater risk (OR, 2.51: 95% CI, 1.42-3.77) in comparison to permanent workers.
To investigate the dimensions of safety climate among Japanese nurses, an anonymous self-administered questionnaire survey was conducted. The subjects involved in the survey included 293 full-time nurses (registered nurses and licensed practical nurses) working in a public hospital, excluding directors of nursing. A total of 221 of the 293 nurses answered the questionnaires. Among 221 questionnaires, the questionnaires, which had missing values in the question items used in this study, were excluded from the analyses. Consequently, a total of 201 questionnaires were analyzed. The average age of the subjects was 34.7 yr. As a result of exploratory factor analysis, 5 factors were extracted as follows: intellectual development regarding medical safety among nurses, accumulated fatigue, nursing conditions, supervisors' attitudes, and communication with physicians. All the values of Cronback's coefficient alpha among these 5 factors were between 0.804 and 0.892. As a result of the confirmatory factor analysis of the 5 factors, the value of the GFI (Goodness of Fit Index) was 0.868. The value of the CFI (Comparative Fit Index) was 0.943. The value of the RMSEA (Root Mean Square Error of Approximation) was 0.062. The results of this study will contribute to the investigation of the dimensions of a nurses' safety climate scale in the future. The associations between the dimensions of the safety climate and the motivation to work toward improving patients' safety among Japanese nurses will need to be examined, as will those between the dimensions of the safety climate and actual clinical mistakes.
Research laboratories in a university were investigated for air-borne levels of legally designated organic solvents and specified chemical substances. Repeated surveys in 2004-5 (four times in the two years) of about 720 laboratories (thus 2,874 laboratories in total) revealed that the solvent concentrations were in excess of the Administrative Control Levels only in a few laboratories (the conditions improved shortly after the identification) and none with regard to specified chemicals. Thus, working environments were in Control Class 1 in almost all (99.5%) laboratories examined. Such conditions were achieved primarily by extensive installation and use of local exhaust systems. The survey further revealed that types of chemicals used in research laboratories were extremely various (only poorly covered by the regulation) whereas the amounts of each chemical to be consumed were quite limited. For protection of health of researchers (including post- and under-graduate students) in laboratories, therefore, it appeared more appropriate to make personal exposure assessment rather than evaluation of levels of chemicals in air of research laboratories. Considering unique characteristics of research activity, it is important to educate each researcher to make his/her own efforts to protect his/her health, through supply of knowledge on toxicity of chemicals as well as that on proper use of protective equipments including exhaust chambers.
In Taiwan, secondary copper smelters and zinc recovery plants primarily utilize recovering metal from scrap and dross, and handles mostly fly ash and slag with high temperature to produce ZnO from the iron and steel industry. The materials may contain organic impurities, such as plastic and organic chloride chemicals, and amounts of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are produced during the smelting process. Therefore, secondary metal recovery industries are major emission sources of PCDD/Fs, which may have been demonstrated to elicit oxidative stress and to involve the production of plasma malondialdehyde (MDA). Many studies have also indicated that the intake of antioxidants, smoking, age and exposure to environmental pollutants may be implicated to DNA damage or lipid peroxidation. This study therefore aims to elucidate the roles of occupational exposure like joining the smelting work, age, smoking and alcohol status, and antioxidant intake on oxidative damage in secondary metal recovery workers in Taiwan. 73 workers were recruited from 2 secondary metal recovery plants. The analysis of 8-hydroxydeoxyguanosine (8-OH-dG) in urine, DNA strand breakage (comet assay) and lipid peroxidation (MDA) in blood samples were completed for all of the workers. The results showed that the older subjects exhibited significantly lower levels of 8-OH-dG and MDA than younger subjects. Our investigation also showed that working departments were in related to plasma MDA and DNA strand breakage levels of nonsmokers, however, the observation become negligible in smokers. And it is implicated that cigarette type might affect 8-OH-dG levels in secondary metal recovery workers. Since, adding to results above, the MDA level in production workers was significantly higher than those in managerial departments, it is important for the employers to make efforts on improving occupational environments or serving protective equipments to protect workers in secondary metal recovery factories.
To investigate the influences of a merger on employees in a Japanese company, changes of subjective stress and stress-related symptoms after a merger announcement in a major Japanese financial company were explored using longitudinal study surveys. Seventy-one participants responded to the first and second questionnaires, consisting of stress and symptoms, personal characteristics, lifestyle, medical examination, and work-related factors. After the merger announcement, the prevalence of subjective stress, anxiety, and impatience increased significantly from 46.5% to 78.9%, 18.3% to 40.8%, and 15.9% to 29.0%, respectively. The study suggests that subjective stress and stress-related symptoms may increase after a merger announcement. To reduce the negative impact of mergers, employers are expected to provide mental health-promotion programs in a merger-planning company.
The purpose of this pilot study was to examine differences in gene expressions by cDNA microarray analysis of hand-arm vibration syndrome (HAVS) patients. Vein blood samples were collected and total RNA was extracted. All blood samples were obtained in the morning in one visit after a standard light breakfast. We performed microarray analysis with the labeled cDNA prepared by reverse transcription from RNA samples, using the Human CHIP version 1 (DNA Chip Research Inc, Yokohama, Japan). There are 2,976 genes on the chip, and these genes were selected from a cDNA library prepared with human peripheral white blood cells (WBC). Different gene levels between the HAVS patients and controls, and between groups of HAVS with different levels of symptoms, were indicated by the randomized variance model. The most up-regulated genes were analyzed for their possible functions and association with the occurrence of HAVS. From the results of this pilot study, although the results were obtained a limited number of subjects, it would appear that cDNA microarray analysis of HAVS patients has potential as a new objective method of HAVS diagnosis. Further research is needed to examine the gene expression with increased numbers of patients at different stages of HAVS.