Proposal and practicality of an alternative blue-light hazard risk assessment method for high-intensity white-light sources at workplaces.

Objectives. It is prescribed to determine blue-light hazard (BLH) weighted radiances, LB, for an assessment of spotlights with an angular subtense α≥11mrad. The BLH weighted irradiance, EB, can be used alternatively for smaller sources. Appropriate instruments are not common among persons commissioned with risk assessment (RA), and especially LB measurements may be challenging. Therefore, a practical BLH RA approach is proposed that is based on illuminance, Ev, pre-calculated blackbody BLH efficacies of luminous radiation, KB,vPlanck, and solid angle considerations. Methods. The practicality of this method was examined and compared against other RA approaches. Results. To ensure comparability of the applied instruments, measurements were performed close to a radiance standard, showing deviations within the lamp's expanded uncertainties (<4%), whereas the deviations were ±15% for longer distances. Focusing on a complex light-emitting diode (LED) spotlight, all detected values could be converted to LB by means of the RA methods within ±20%. Two field tests with several spotlights yielded maximum permissible exposure durations (MPED) obtained from the different RA approaches that agreed among each other within uncertainties largely below ±30%. Conclusion. The general practicality of the proposed Ev method can be concluded for a workplace BLH RA of white-light sources.

The influence of light exposure and chronotype on working memory in humans.

Here we examine how exposure to blue (peaking at λ=470 nm), green (peaking at λ=505 nm) and red (peaking at λ=630 nm) light affects subsequent working memory performance measured with visual N-back tasks and associated functional brain responses in participants with extreme morning and extreme evening chronotype. We used within-subjects experimental manipulation on carefully selected samples and state of the art equipment for light exposure. The results show no differences between extreme morning-type and evening-type individuals in N-back task performance. We also did not replicate the alerting effect of exposure to blue wavelength light, supposedly enhancing performance on cognitive tasks. However, we found higher brain activity in the morning hours for extreme morning in comparison to extreme evening chronotype in several frontal areas of the precentral gyrus, middle and superior frontal gyri and in the occipital gyrus. This may indicate increased strategic or attentional recruitment of prefrontal areas, implicated in compensating working memory load in the morning type.

[Potential impact of colors of filters used in sunglasses on the melatonin suppression process]. / Potencjalny wplyw barwy filtrów w okularach chroniacych przed olsnieniem slonecznym na wydzielanie melatoniny.

BACKGROUND: In this article the methods for determining spectral transmittance of optical radiation in the visible waveband range through selected materials used as optical filters against solar glare were described. MATERIAL AND METHODS: Transmittance coefficients specified for the fraction of light passing through tested filters, taking into account the mechanism of eye adaptation to daylight and night vision and the melatonin suppression process were compared for 4 dyed sunglass filters. RESULTS: The values of transmittance coefficients specified for wavelength bands, 380-780 nm (for visible range) and 425-560 nm (for blue light range affecting the melatonin suppression process) were determined. CONCLUSIONS: The use of sunglasses with different color filters modifies the spectral characteristics of transmittance (spectrum) of visible light reaching the eye (including blue radiation) in such a way that it may have a potential impact on the melatonin suppression process. Med Pr 2017;68(5):629-637.

Evaluation of discomfort glare in the 50+ elderly: experimental study.

OBJECTIVES: The aim of the study was to analyze discomfort glare sensation in subjects aged 50 years and more in comparison with younger subjects (i.e. younger than 35 years of age). MATERIAL AND METHODS: The experiments were performed on a computer workstation placed in controlled lighting environment where 2 discomfort glare conditions were modeled. Each participant performed for about 1 h specially designed visual tasks, including the tests with Landolt's rings presented on the screen by a computer program. The glare evaluation method consisted of subjective evaluation of discomfort glare on the semantic glare rating scale, tests of mesopic contrast and glare sensitivity, subjective assessment of lighting quality and asthenopic symptoms. The time needed to perform the task and the number of mistakes were also recorded. The subjective evaluation of glare was compared with the Unified Glare Rating (UGR) index calculated by the DIALux simulation program. RESULTS: A higher percentage of the younger group subjects assessed glare after the experimental session as uncomfortable and intolerable than in the 50+ group, who more often assessed glare as acceptable. The assessment of discomfort glare in the younger group corresponded to higher UGR value compared to UGR value calculated by DIALux. In the 50+ group, such correlation was found only for lower discomfort glare (UGR = 19). The results showed that younger participants more frequently suffered from visual fatigue and assessed lighting as less comfortable. However, the mesopic glare sensitivity increased significantly after the experiments only in the 50+ group under both glare conditions. CONCLUSIONS: The obtained results showed that discomfort glare sensation changes with age. The younger population seems to be more sensitive and demanding than the older one in relation to discomfort glare limiting, in spite of the lack of significant objective measures of fatigue. The exposure of the elderly to bigger discomfort glare could adversely affect the objective measures of fatigue like mesopic glare sensitivity and visual performance.

[Occupational exposure of welders to ultraviolet and "blue light" radiation emitted during TIG and MMA welding based on field measurements]. / Ocena narazenia zawodowego spawaczy na promieniowanie nadfioletowe i "swiatlo niebieskie" podczas spawania metoda TIG i MMA na podstawie wyników pomiarów na stanowiskach pracy.

BACKGROUND: The aim of the study was to present the results of welders' occupational exposure to "blue light" and UV radiation carried out at industrial workstations during TIG and MMA welding. MATERIALS AND METHODS: Measurements were performed at 13 workstations (TIG welding: 6; MMA welding: 7), at which different welding parameters and materials were used. The radiation level was measured using a wide-range radiometer and a set of detectors, whose spectral responses were adequately fit to particular hazard under study. The measurement points corresponded with the location of eye and hand. RESULTS: The highest values of eye irradiance were found for aluminum TIG welding. Effective irradiance of actinic UV was within the range E(s) = 7.79-37.6 W/m2; UVA total irradiance, E(UVA) = 18-53.1 W/m2 and effective blue-light irradiance E(B) = 35-67 W/m2. The maximum allowance time ranged from 1.7 to 75 s, which means that in some cases even unintentional very short eye exposure can exceed MPE. CONCLUSIONS: The influence of welded material and the type of electrode coating on the measured radiation level were evidenced. The exceeded value of MPE for photochemical hazard arising for the eyes and skin was found at all measured workstations. Welders should use appropriately the eye and face protective equipment and avoid direct staring at welding arc when starting an arc-welding operation. Besides, the lack of head and neck skin protection can induce acute and chronic harmful health effects. Therefore, an appropriate wear of personal protective equipment is essential for welders' health.

Occupational exposure to solar ultraviolet radiation of Polish outdoor workers: risk estimation method and criterion.

This paper presents occupational skin exposure to solar ultraviolet radiation (UVR) of 122 Polish outdoor workers in spring and summer. In 65% of the cases, it was significant and exceeded 10 standard erythema doses (SED) during a work shift. The results provided grounds for (a) modifying hazard assessment based on the skin exposure factor proposed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and (b) developing a criterion of risk estimation. The modified method uses the UV index (UVI) instead of the geographical latitude and season factor. The skin exposure factor (Wes) of one is the criterion of risk estimation. Risk is low if the estimated value of Wes does not exceed one. If it does, suitable preventive measures are necessary and a corrected skin exposure factor (Wes *) is calculated to minimize its value to at least one. Risk estimated with that method was high in 67% of the cases.

Simulation of reflected and scattered laser radiation for designing laser shields.

This paper presents a computer simulation of reflected and scattered laser radiation for calculating the angle of laser shields performed with the Laser Shield Solver computer program. The authors describe a method of calculating the shield angle for laser shields which protect workers against reflected and scattered laser radiation and which are made from different materials. The main assumptions of the program, which calculates and simulates reflected laser radiation from any material and which can be used for designing shield angles, are presented. Calculations are compared with measurements of reflected laser radiation. The results for one type of laser and different materials which interacted with a laser beam showed that the Laser Shield Solver was an appropriate tool for designing laser shields and its simulations of reflected laser radiation distribution have practical use.

[Etiological agents of urinary tract infections in children treated at the Institute of Mother and Child]. / Czynniki etiologiczne zakazen ukladu moczowego u dzieci leczonych w Instytucie Matki i Dziecka.

BACKGROUND: Urinary tract is a common site of bacterial infections in children. The main etiological agents of infection are Gram negative bacteria from the Enterobacteriaceae in particular of intestinal origin. The uropathogenic strains may indicate resistance for many antibacterial drugs. AIM: The aim of this study was an analysis of urine samples from outpatient or hospitalized children treated at the Institute of Mother and Child in Warsaw, in the years 2006-2007. The frequency of individual bacterial species and antibiotic susceptibility were investigated. MATERIALS AND METHODS: In all, 2096 urine samples from patients treated at the Institute of Mother and Child were investigated. Bacteriuria was examined and antibiotics susceptibility was estimated. Biochemical tests were used for the identification of uropathogenic strains. Antibiotic susceptibility was examined using standard diffusion discs methods. RESULTS: During 2006-2007, in all 2096 urine samples were taken, of which 313 were positive (14.9%). E. coli was the most often isolated bacteria (54%) and enterococci dominated in Gram-positive bacteria. CONCLUSIONS: Enterobacteriaceae were the most frequently isolated bacteria. Most of the antibiotics used in the treatment of urinary tract infections had high antibacterial activity except for ampicillin.

The effect of an ergonomic intervention on musculoskeletal, psychosocial, and visual strain of VDT data entry work: the Polish part of the international study.

A group of routine data entry operators (female) was included in the Polish MEPS (musculoskeletal--eyestrain--psychosocial--stress) study. Before the intervention, ergonomic assessment revealed improper working conditions such as inadequate lighting, uncomfortable chairs, and lack of forearm and wrist support while medical examination revealed that trapezius muscle load along with upper arm, head and back angles were higher than advisable. Subjects complained about neck and shoulder pain, visual problems, and psychosocial conditions. The ergonomic intervention included installation of new luminaires and Venetian blinds, new chairs, repair of ventilators, and optometric corrections. The results after the intervention showed mainly improvement in chair comfort, lighting conditions, visual strain, and sitting posture. However, financial limitations did not allow satisfactory completion of the intervention leading to a mixed interpretation of the results.

Visual strain and lighting preferences of VDT users under different lighting systems.

Lighting influences users' visual strain and well-being. Therefore creating lighting that ensures visual work conditions do not result in visual fatigue is a preventive activity. The aim of the study was to model different lighting systems for visual display terminal (VDT) work and to determine their influence on users' visual strain and preferences. The results of the study showed that visual fatigue was lowest for indirect and compound lighting systems. On the other hand, in general, direct lighting realized by "dark-light" luminaires was the most preferred lighting system. Some interesting differences related to age, gender, and VDT work experience were found. On the basis of the obtained results lighting designers can be provided with some guidance.