1 State Institution “Kundiiev Institute of Occupational Health of the NAMS of Ukraine, Kiev, Ukraine
2 Lashkarev Institute of Semiconductor Physics of the NAS of Ukraine, Kiev, Ukraine
Introduction. Blue light (BL) covers the region of the short-wave visible radiation (380-500nµ) and has high photon power energy (5W/m2) the prolonged exposure to which can cause degenerative phenomena in the retina. The severity of this problem is caused by the anxiety – is it possible to use new high-effective light sources - cold-white LEDs with the color temperature (Tcolor) 4500 K and higher, due to the presence of BL in its spectrum, which affects the epiphysis of the brain and the pineal gland, producing a melatonin hormone. This can cause an adverse effect on its secretion and on the circadian rhythm in a human. To this date, no physiological studies have been carried out in conditions of a long-term surveillance of the general state of workers in the light environment (LE) with cold-white light sources (CWLS) for substantiation of their use in the lighting systems.
Purpose of the research. To study and evaluate the state of the human body, using indices of the functional state of the visual system on the background of the study of indicators of the cardiovascular and central nervous systems in office workers, performing their tasks in natural conditions within a working day and a working week in the light environment with CWLS at Tcolor 6400 K under in the uniform lighting of 600 lx. The indices of physiological functions based of the previously conducted studies on the similar contingent of persons who worked about 10 years in conditions with fluorescent lamps (FL) of 500-550 lx and Tcolor 6200 K were used as the control.
Materials and research methods. The first stage - computer modeling of photometric parameters according to the program DiaLux for creating a design of the lighting device for the general uniform lighting of 600 lx with the CWLS and Tcolor 6400 K in the working room of “The Handling Company of Ukraine” in the city Kiev, in which office employees worked constantly for 8-hours a work day (from 9.00 to 18.00, with one hour break). At the density of work about 92%, they performed their duties of the medium heaviness (IV category of work, according to the State Building Norms (DBN) (Ukrainian standard) B 2.5-28-2006 . The intensity of nervous-emotional and sensory strain of work corresponded to Class 3.1., by the Hygienic Classification of Work. The second stage - selecting subjects and their training in understanding the tasks. 12 practically healthy persons, aged 28-35, with the work experience from 5 to 10 years have been selected. The third stage – studies of the potential abilities of the visual system, accommodation-convergent stability with the help of achromatic adisparapia, activity of the nervous processes in the retina with the help of negative sequential contrast (NSC), quantitative and qualitative indices of the static and dynamic visual performance (VP) on the background of research of parameters of the cardiovascular and central nervous systems with the use of Golovin-Sivtsev tables for close distances, Adisparopia device, NSC tables, special test tables, including visometry. A general medical examination was carried out according to the accepted methods. 5 series of studies in the dynamics of a working day over a working week were conducted, in one week, in a month, in 2.5 months and after 4 months of work in the new lighting environment with SWLC and Tcolor 6400 K. Also, a questionnaire was used to assess the subjective perception of the new LE.
The results. The data of the studies show an oscillatory character of functions with a small amplitude and gradual increase of their level by the end of the studies throughout the whole period, pointing to the character of adaptive mechanisms to the new light environment. It is established, that the increase in reserves of accommodation from 2,4-2,5 D to 3,66 D (p <0,05) was recorded in a month. The indices of achromatic adisparopia (p<0.05) by the time of the initial effect and by the total time of unclear vision after 4 months increased during the whole week of research in comparison with the control. The indices of the short-term memory (p<0.05) in the first week were increased significantly and highly stabilized at the end of the study. The analysis of parameters of the (VP) (p<0.05), reflecting the integral state of functions of the eye resolution, contrast sensitivity and speed of differentiation demonstrate their stability over the whole period of research with the increase of the level close by the end, in comparison to the control group (CG). The data of the subjective indicators of the comfort environment with the SWLC and (Tcolor) 6400 K showed a high score of 4.3-4.4 points by the 5-point assessment according to the questionnaire.
Conclusion. On the basis of the analysis of the conducted physiological studies on the radiation influence of the blue-white LED light with (Tcolor) 6400 K on the functional state of visual, central nervous and cardiovascular systems in office workers in production conditions it is established, that on the background of the general satisfactory subjective estimation of LE, the oscillatory character of research functions can be traced with a small amplitude and gradual increase of their level and their higher stabilization by the end of the study as compared to the CG. This gives the proof to recommend their usage for the general uniform lighting systems taking into account our recommendations.
Keywords: blue light, light environment, cold white LEDs, experimental studies, office workers, physiological studies, visual performance, questionnaires.
ORCID ID of authors and their contribution to the preparation and writing of the article:
Martirosova VG (ORCID ID 0000-0002-2777-1724) - organization and carrying out of experimental research on production, processing of research data, formulation of conclusions;
Sorokin VM - statement of the purpose of research, organization and control of installation of lighting systems in production;
Nazarenko VI (ORCID ID 0000-0002-5238-4312) - literature review, questionnaire development, processing of research materials, formulation of conclusions;
Cherednichenko IM (ORCID ID 0000-0001-6654-1334) - literature review, cardiovascular system research in experimental dynamics, processing of research data;
Tikhonova NS (ORCID ID 0000-0001-5856-9919) - control of parameters of light environment in experiment, conducting of questioning;
Talk A. - control of microclimate parameters in experiment, conducting of questioning.