Objectives: In factories for glassware production, workers are exposed to intense visible light emitted from hot objects such as furnaces and molten glass. High exposure to short-wavelength visible light, called blue light, can cause photoretinopathy. The objective of this study was to quantify the blue-light hazards associated with glassware production. Methods: Spectral radiances of walls and heating elements inside furnaces were measured, as well as those of molten glass placed inside furnaces in a factory producing crystal glass crafts. The factory had two reheating furnaces, three melting furnaces, and a furnace for preheating blowpipes. The effective radiances of the inner furnace walls, the heating elements, and the molten glass were calculated from the measured spectral radiances and compared with the threshold limit value (TLV) in accordance with ACGIH guidelines. The temperature of each light source was determined by comparing the measured spectral radiance with that of a black body. Results: The measured effective radiances were in the range of 0.00498–0.708 mW/cm²sr and increased steeply with increasing light source temperatures in the range of 1,075–1,516 °C. The effective radiance of each light source was nearly equal to the effective radiance of the black body at the same temperature. Conclusions: The effective radiances of walls, heating elements, and molten glass inside the furnaces are lower than one tenth of the TLV for exposure durations longer than 10⁴ s per day. Thus, it is not hazardous to view these light sources. However, the effective radiance at a higher light source temperature of approximately 1,800 °C will exceed the TLV. In this case, hot objects in a workplace for glassware production may present blue light hazards.

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Abstracts: Objectives: The period of leisure is an appropriate time to recover from work-induced fatigue, though some recovery takes place during rest breaks at work. Recently, much attention has been paid to the critical role of leisure activity in recovery. However, the findings relevant to shiftwork nurses who cannot take a day-off regularly are limited. This study explored how leisure activity during days off and shift work schedule are associated with recovery from fatigue in nurses working rotating shifts. Methods: A total of 426 nurses working rotating shifts at a university hospital returned a questionnaire regarding leisure activity and fatigue (response rate: 81.5%). Nurses were eligible for this study if they were female, worked 2 or 3 shifts, and had no missing data. A total of 390 respondents satisfied the inclusion criteria. A factor analysis classified their responses on how to spend an assumed period of two consecutive days off into three activity types: outdoor-, sleep-, and indoor-oriented. Fatigue (recovery from fatigue, accumulated fatigue, burnout), work conditions (working time, overtime, nightshift napping), sleep (sleep duration before day shift or day off, sleepiness) were measured. These data were analyzed using a two-way mixed model analysis of covariance (type [outdoor, sleep, indoor], shift schedule [two or three-shift system]). Covariates included age, length of career, partner, children, and hospital ward. Multiple regression analyses were performed to examine the factors determining the level of fatigue. Results: Outdoor-oriented nurses showed significantly faster fatigue recovery, lower accumulated fatigue and less burnout symptoms than others, regardless of the shiftwork schedule. In contrast, sleep-oriented nurses showed significantly slower recovery from fatigue. Besides, their level of fatigue deteriorated more when they worked under a 3-shift system (counter-clockwise) compared with under 2-shift system (with mainly 16-hour nightshift). Multiple regression analysis indicated that sleep-oriented type of leisure activity, workload perception of working time, work-induced insomnia and length of nightshift naps were significantly related to fatigue-related outcomes. Conclusions: The primary finding of this study suggests that the level of fatigue is associated with the type of leisure activity, especially sleep-oriented activity, during shiftwork nurses’ days off. Also, ensuring sufficient nightshift nap time may be one of the most important nightshift-related factors for recovery from fatigue. The present findings may have implications for appropriate activities during days off as factors facilitating recovery from work, though further investigations are needed to examine the causal links.

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