Iran Occupational Health

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  Background and aims: Production of fixed concentration of vapors from pure liquid has many applications in laboratory and field studies of occupational health and toxicological research and also in calibration of air pollutant measurement devices of the workplaces. In this study, the advantages and disadvantages of different concentration generation methods were discussed. In addition two selected methods were compared and the factors that influence the generated concentration were identified.

  Methods: In order to make certain concentrations of styrene, evaporation and injection methods were used. In evaporation system air was blown in a 250 (ml) midget impinger in two modes (close to the liquid surface and inside the liquid). For injection system a syringe pump (3100 Graseby, Smiths Co) was used. Affecting factors on concentration stability like temperature, flow rate, position of nozzles have been investigated.

  Results: To produce 300(ppm) of styrene vapor concentrations in RH=19%, coefficient of variation (C . V) of the concentrations generated in bubbler and syringe pump systems were 2.86 and 2.01 percent respectively. Syringe pump system reached to the equilibrium approximately in 60 (min), while for the evaporative systemit took 105 (min).When the nozzle of the bubbler was placed close to the liquid surface, the coefficient of variation was 1.97% , however, when it was placed inside the liquid, the C.V was 2.52% .

  Conclusions: Controlling the influencing factors like temperature and flow rate are most important points for the generation of constant concentrations. The low coefficient of variation in the syringe pump system proved the better capability and functionality of this system compared to bubbler system. One advantage of the syringe pump system is that it is not dependent on liquid level of the container.

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Background and aims: Lighting directly and indirectly affects employees' mental health and their performance. Good lighting is required for good visibility of the environment and should provide a luminous environment that is human-friendly and appropriate for the visual task performed. Optimal lighting is one of the most important issues in providing the physical conditions of different places, especially the workplace. Lighting can provide comfortable working conditions, especially visual comfort. Life on Earth cannot be imagined without light. Defects in the qualitative and quantitative aspects of lighting in the workplace can cause visual discomfort and reduce the productivity and efficiency of an individual. Therefore, monitoring the intensity of brightness and color temperature of light is essential to maintain and enhance the health of employees. The quantity and quality of lighting can also affect one's mental health. For example, one of the factors associated with depression is the defect in the quantity and quality of ambient lighting. Correlated color temperatures (CCT) of light play an important role in human psychological and physiological needs. In regards of human perception, two of the most important characteristics of lights are illumination and correlated color temperature (CCT). studies have proven that different CCT provided by different lighting are important in affecting human beings psychologically and physiologically, through their visual and non-visual processes.. According to European standard EN 12665, visual comfort is defined as a person's mental well-being in the workplace. Studies on lighting in industrial environments have been conducted more frequently and public and office environments have received less attention. CCT is found to have effects on visual and mental fatigue. The right selection of CCT in an office environment will benefit its occupants in terms of visual comfort and reduction of daytime sleepiness. Studies have shown that insufficient and uncomfortable lightning conditions in office environments increase the risk of visual and ergonomic disorders in long term. The aim of this study was to evaluate the illumination and color temperature and its relationship with visual comfort in administrative staff in Hamadan city (west of Iran).
Methods: This cross-sectional study was conducted in 50 rooms and among 70 staff of Hamadan University of Medical Sciences and random sampling. In this study, the intensity of illumination at the work surface and at the height of the individual eye The intensity of the local illumination at the work surface and at the level of the individual eye level was measured at the user's point of view and the angles and distances were accurately observed and measured with the presence of the user in the presence of semiconductors or other factors. Also intensity of the general lighting based on the Illuminating Engineering Society of North America (IES) in terms of lux and color temperature of light source in terms of Kelvin at the work surface using new device Sekonic C-7000 SpectroMaster was measured. The device is capable of simultaneously measuring brightness intensity (Kendel / lux), color temperature, color expression index and wavelength. The device has an accuracy of over 1 nm. Visual comfort of visual display terminal users was assessed using visual fatigue questionnaire. Visual fatigue questionnaire with15 items and four components of eye stress, visual impairment, eye surface disorder and extra ocular problems was used for this purpose. This questionnaire is rated on a Likert scale ranging from 0 to 10 and none to very severe.
Results: The results showed that the mean age of the staff was 42.18± 7.46 years with a minimum of 25 and a maximum of 62 years. In this study, the average general illumination intensity of the studied rooms was 437.57 ±116 and the average local illumination intensity was 341.16±109 and 307.13±195 respectively. Also, the intensity of illumination, general, local level at work and perpendicular were 30.6%, 33.9% and 38.4% lower than the national occupational health limits. The average color temperature during the working shift in 56% of the rooms was more than 4000 °K. The frequency of low and high visual fatigue score was 61.4% and 38.6% respectively. There was a statistically significant relationship between brightness intensity and visual fatigue of the staff during the study. The results of the study showed that people with room temperature below 4000 ° C had higher frequency of visual fatigue in these subjects. Chi-square test confirmed the relationship between the intensity of local illumination and visual fatigue of the subjects (p <0.05). The distribution of brightness intensity at most of the surfaces of the investigated environments was largely uneven (less than 0.6). Finally, the incidence of visual fatigue expressed by staff has been considerable
Conclusion: local and general luminance was lower than the Iranian occupational exposure limit and it had not a suitable condition in term of quality and quantity. Light intensity distribution in office rooms was undesirable. The results of this study showed a significant relationship between artificial lighting and color temperature with visual fatigue. The results showed that in rooms which more hours of artificial lighting was used in the workplace and had less natural light, participants suffered visual fatigue. In rooms where the color temperature was close to that of the sun, people had less visual fatigue. Causes of poor quality of light are insufficient number of light sources as well as the use of cold light fluorescent lamps and inappropriate color temperature of some lights and even the color of interior surfaces and angles of the individual desk relative to the window and the use of dark curtains It indicates that in designing lighting and environmental factors related to the office environment, the quantity and quality of light sources and environmental factors influencing the proper lighting and visibility of people were less considered Defects in artificial light intensity and color temperature of the sources affect the visual acuity of the administrative staff and increase the visual fatigue of the employees. According to the Study the modification of lighting systems and training of Staff in order to prevent the visual disturbances associated with it, while improving the artificial lighting system of these places.