Journal of Occupational Health
Online ISSN : 1348-9585
Print ISSN : 1341-9145
ISSN-L : 1341-9145
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Issue Information
  • Satoru Ueno, Shin-ichi Sawada
    2019 Volume 61 Issue 2 Pages 157-164
    Published: March 20, 2019
    Released: March 25, 2019

    Objectives: This study aimed to investigate the effects of ventilation openings in commercial industrial safety helmets (ISHs) on evaporative heat dissipation.

    Methods: Seven models of commercial ISH were examined quantitatively by a sweating thermal head manikin (SHM) with six separate zones. To simulate summer outdoor conditions, the measurements were done in a climate chamber, with the room temperature and relative humidity set at 34.0°C and 50%, respectively. The shell temperature of SHM was set at 34.0°C. Wind was blown from the front or left side at 1.0, 2.0, and 3.0 m/s. The necessary heat flux to keep the manikin skin temperature at 34.0°C was counted as evaporative heat dissipation in each zone.

    Results: Openings at the front and back, and openings between the body and brim of the helmet played a significant role in increasing the heat flux in Forehead zone, but in all zones as a total, the effects were not significant. Heat flux for ISH with openings on both the right and left sides was not significantly different from that without openings.

    Conclusions: Our study utilizing SHM showed that ventilation openings on both the right and left sides or front and back sides of commercial ISHs were not significantly effective in increasing total evaporative heat dissipation under an equivalent temperature of ambience and manikin shell. Further improvements on ISH are needed to increase evaporative heat dissipation.

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  • Mazloumi Adel, Rostamabadi Akbar, Garosi Ehsan
    2019 Volume 61 Issue 2 Pages 165-174
    Published: March 20, 2019
    Released: March 25, 2019

    Objectives: Maintenance and promotion of employees' work ability is one of the important social goals. This study is aimed at investigating psychometric properties of the Persian translation of work ability index (WAI).

    Methods: A total number of 750 employees were randomly selected from car manufacturing and petrochemical industries. Reliability of the questionnaire was determined using test-retest and Cronbach alpha coefficient. Factor analysis was used for assessing construct validity. To determine discriminant validity, the mean score of total WAI was compared between workers with high and low sick leave rate.

    Results: Intraclass correlation coefficients for its seven dimensions were estimated higher than 0.7. The questionnaire showed a good internal consistency, Cronbach α = 0.78. Factor analysis showed a three-factor structure model for Persian translation of WAI including: mental resources, self-perceived work ability, and presence of disease and health-related limitation. A good level of discriminant validity was observed for all WAI dimensions except the item “work ability regarding work demands.”

    Discussion: The study findings indicate that the Persian version of WAI questionnaire has good psychometric properties of internal consistency and test-retest showed a good reliability of WAI questionnaire, which is in line with those found in previous studies. Therefore, this tool can be considered as a reliable instrument for assessing work ability.

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  • Hiroki Fujita, Kenji Sano, Tomio Baba, Tadashi Tanaka, Kyoko Ohno-Mats ...
    2019 Volume 61 Issue 2 Pages 175-181
    Published: March 20, 2019
    Released: March 25, 2019

    Objectives: Blind working (BW) time (time during which vision is not required), the interblink interval (IBI), and subjective symptoms were investigated in workers using visual display terminals (VDTs).

    Subjects and Methods: To investigate BW time, 10 VDT users were instructed to close their eyes when this did not interfere with their work. They were video recorded for 60 minutes using a webcam attached to the display on which they were engaged in regular data input tasks, and BW time was measured. The values of the IBI during the final 20 minutes of the BW experiment and during the final 20 minutes of normal working without BW were compared. A questionnaire was administered to investigate subjective symptoms using a visual analogue scale.

    Results: The total BW time during the final 20-minute period was 20.6-121.0 seconds (1.7%-10.1%). The mean IBI of 5.5 ± 4.5 seconds during the BW experiment was not significantly different from that of 6.2 ± 5.6 seconds during normal working, and the mean of three IBIs immediately after BW during the BW experiment was 2.7 ± 1.0 seconds, significantly shorter than the 6.2 ± 5.6 seconds during normal working. Dry eye, ocular fatigue, and blurred vision during normal working improved when subjects were engaged in BW.

    Conclusions: VDT users could engage in BW during VDT work, the IBI was shorter immediately after BW, and subjective symptoms improved. These results suggest that BW may provide a more effective measure for the management of VDT working time.

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  • Emi Okazaki, Daisuke Nishi, Ryoko Susukida, Akiomi Inoue, Akihito Shim ...
    2019 Volume 61 Issue 2 Pages 182-188
    Published: March 20, 2019
    Released: March 25, 2019

    Objectives: The aims of the study were to investigate the association between working hours, work engagement, and work productivity, and to examine if work engagement moderates the influence of working hours on work productivity.

    Methods: We used cross-sectional data from the Japanese occupational cohort survey, which involved 2093 employees in a manufacturing industry. Working hours were self-reported by the study participants. Work productivity was assessed with absolute presenteeism based on the scale of the validated Japanese version of World Health Organization Health and Work Performance Questionnaire (WHO-HPQ). Work engagement was assessed with the Nine-item Utrecht work Engagement Scale (UWES-9). Univariate and multivariable regression analyses were conducted to examine the association of working hours and work engagement with work productivity. We also carried out stratified multivariable regression analysis separately for those with high-work engagement and those with low-work engagement.

    Results: Working >40 to 50 hours per week and >50 hours per week were significantly positively associated with work productivity in univariate analysis. However, the significant association no longer held after adjusting for work engagement. Work engagement was positively associated with work productivity even after controlling for potential confounders. Working hours were not significantly associated with work productivity among those with high-work engagement or among those with low-work engagement.

    Conclusions: Working hours did not have any significant associations with work productivity when taking work engagement into account. Work engagement did not moderate the influence of working hours on work productivity, though it attenuated the relationship between working hours and work productivity.

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  • Rumi Tsukinoki, Tomonori Okamura, Nagako Okuda, Aya Kadota, Yoshitaka ...
    2019 Volume 61 Issue 2 Pages 189-196
    Published: March 20, 2019
    Released: March 25, 2019

    Objectives: Worksite-based programs present a simple and effective approach to facilitate weight reduction in employees. Despite the importance of 1-year weight loss maintenance, studies have generally focused on the short-term effects of weight reduction programs. In addition, little is known about the long-term weight maintenance outcomes in Asian populations. We examined the long-term maintenance effects of a worksite-based weight reduction program among Japanese men with cardiovascular risk factors.

    Methods: The study sample comprised 58 overweight men with cardiovascular risk factors who had voluntarily participated in a randomized crossover trial involving a 3-month weight reduction program. Participants were followed up for 1 year after the trial concluded, and both groups were merged for the analysis. We compared the changes in body weight before the post-trial follow-up and after 12 months to examine the long-term maintenance effects of the program. Changes in other cardiovascular risk factors (eg, waist circumference, blood pressure, lipid measures, and diabetes-related measures) were also examined.

    Results: Both groups of study participants achieved weight loss during the weight reduction program. Total 53 participants (91.4%) completed the 12-month post-trial follow-up. There were no significant changes in mean body weight (mean: −0.11, 95% confidence interval: −0.7-0.49 kg) and other cardiovascular risk factors between the beginning and end of the follow-up period.

    Conclusions: This study showed that the worksite-based weight reduction program not only enabled short-term weight loss, but that the participants were able to successfully maintain their weight for 1 year after the program without any supplementary interventions.

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Brief Report
  • Xiangjing Gao, Hua Zou, Xiaohui Xu, Lifang Zhou, Shichuan Tang, Weimin ...
    2019 Volume 61 Issue 2 Pages 197-202
    Published: March 20, 2019
    Released: March 25, 2019

    Objectives: To provide a guideline for assessing the occupational exposure to nanomaterials in workplaces in China.

    Methods: Based on the basic requirement for the sampling of harmful substances, condensation particle counter/optical particle counter (CPC/OPC) was selected as the tool and the total number concentration (TNC) was used as an index to measure engineering nanomaterials in workplaces.

    Results: The strategy included instrument preparation, identification of particle-emission source, particle-property analysis, measurement of background concentration, concentration measurement based on working activity, concentration calculation and analysis, and recording of measurements.

    Conclusions: The draft guideline based on traditional industrial hygiene practices can be used to identify the emission source of nanomaterials, qualitatively and quantitatively assess exposure to nanomaterials in workplaces.

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Letter to the Editors