RESUMEN
BACKGROUND: The visual conditions for computer work are complex and include several factors that need to be well controlled. These factors include the lighting system, the design of the computer and screen itself, the screens position and orientation within the room, the surface reflectances and colours of the room, and the visualability of the worker. OBJECTIVE: The objective was to review the literature (including standards) on lighting for computer work in an accessible summary. This contribution focuses on lighting for computer work, but the reader is reminded of the fact that lighting continuously interacts with the other factors mentioned above. RESULTS/CONCLUSION: The combined visual conditions shall enable the worker to see and perform the work task without causing unnecessary strain for the eyes or the other parts of the body. The main lighting-related factors in the visual environment to evaluate are: illuminance, luminance, direction of light, glare, correlated colour temperature of the light source (CCT), colour rendering of the light source, and the non-visual effects (such as non-visual flicker). A visual ergonomics checklist is presented as a guide to analyse the visual environment.
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Terminales de Computador , Luz , Iluminación , Enfermedades Profesionales/etiología , Astenopía/etiología , Astenopía/prevención & control , Ergonomía , Deslumbramiento/efectos adversos , Humanos , Diseño Interior y Mobiliario , Luz/efectos adversos , Iluminación/efectos adversos , Iluminación/instrumentación , Iluminación/normas , Dolor Musculoesquelético/etiología , Dolor Musculoesquelético/prevención & control , Enfermedades Profesionales/prevención & control , PosturaRESUMEN
BACKGROUND: Sorting mail into racks for postmen is visually demanding work. This can result in backward inclination of their heads, especially more pronounced for those who use progressive addition lenses. OBJECTIVE: To evaluate the effects of customized working spectacles on the physical workload of postmen. METHODS: Twelve male postmen sorted mail on two occasions: once using their private progressive spectacles and once using customized sorting spectacles with inverted progressive lenses. Postures and movements of the head, upper back, neck, and upper arms were measured by inclinometry. The muscular load of the trapezius was measured by surface electromyography. RESULTS: With the customized sorting spectacles, both the backward inclination of the head and backward flexion of the neck were reduced (3°), as well as the muscular load of the right upper trapezius, compared to sorting with private spectacles. However, with the sorting spectacles, there was a tendency for increased neck forward flexion, and increased sorting time. CONCLUSION: The reduction in work load may reduce the risk for developing work-related musculoskeletal disorders due to the positive reduction of the backward inclination of the head. But the tendency for increased neck forward flexion may reduce the positive effects. However, the magnitude of the possible reduction is difficult to predict, especially since quantitative data on exposure-response relationships are unknown. Alternative working spectacles with inverted near progressive lenses ought to be evaluated. They should still result in a positive reduced backward inclination of the head and may not cause any increased forward flexion.
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Anteojos , Salud Laboral , Servicios Postales , Postura , Brazo/fisiología , Dorso/fisiología , Cabeza/fisiología , Humanos , Masculino , Persona de Mediana Edad , Cuello/fisiología , Músculos Superficiales de la Espalda/fisiología , Análisis y Desempeño de Tareas , Carga de TrabajoRESUMEN
OBJECTIVE: The objective of this study was to evaluate hearing loss among workers exposed to styrene, alone or with noise. DESIGN: This cross-sectional study was conducted as part of NoiseChem, a European Commission 5th Framework Programme research project, by occupational health institutes in Finland, Sweden, and Poland. STUDY SAMPLE: Participants' ages ranged from 18-72 years (n = 1620 workers). Participants exposed to styrene, alone or with noise, were from reinforced fiberglass products manufacturing plants (n = 862). Comparison groups were comprised of workers noise-exposed (n = 400) or controls (n = 358). Current styrene exposures ranged from 0 to 309 mg/m(3), while mean current noise levels ranged from 70-84 dB(A). Hearing thresholds of styrene-exposed participants were compared with Annexes A and B from ANSI S3.44, 1996. RESULTS: The audiometric thresholds of styrene exposed workers were significantly poorer than those in published standards. Age, gender, and styrene exposure met the significance level criterion in the multiple logistic regression for the binary outcome 'hearing loss' (P = 0.0000). Exposure to noise (<85 dBA p = 0.0001; ≥85 dB(A) p = 0.0192) interacted significantly with styrene exposure. CONCLUSIONS: Occupational exposure to styrene is a risk factor for hearing loss, and styrene-exposed workers should be included in hearing loss prevention programs.
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Audiometría de Tonos Puros , Pérdida Auditiva Provocada por Ruido/inducido químicamente , Pérdida Auditiva/inducido químicamente , Ruido/efectos adversos , Enfermedades Profesionales/inducido químicamente , Exposición Profesional , Solventes/efectos adversos , Estireno/efectos adversos , Estimulación Acústica , Adolescente , Adulto , Anciano , Umbral Auditivo , Estudios Transversales , Europa (Continente)/epidemiología , Femenino , Pérdida Auditiva/diagnóstico , Pérdida Auditiva/epidemiología , Pérdida Auditiva/prevención & control , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/epidemiología , Pérdida Auditiva Provocada por Ruido/prevención & control , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Enfermedades Profesionales/diagnóstico , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/prevención & control , Servicios de Salud del Trabajador , Valor Predictivo de las Pruebas , Servicios Preventivos de Salud , Medición de Riesgo , Factores de Riesgo , Adulto JovenRESUMEN
The introduction of sit-stand worktables was examined in this study. Purchasers at four companies were interviewed regarding preparations prior to purchase, follow-up after installation, and if expectations had been fulfilled. Personnel at the four companies answered a questionnaire examining use of the worktables' sit-stand function, and the influence of some variables on this. Utilisation of the sit-stand function was less than what could be expected to relieve static musculoskeletal loading during VDU work. Pain experienced during the past year, and education on the use of the worktable gave rise to modest increases in utilisation. Investment in sit-stand worktables was satisfactory to purchasers, in terms of providing flexible furniture to suit modern organisational dynamics. Users were, in general, positive to the worktables, but showed poor compliance in using them. User and purchaser satisfaction with regard to improving individual health ergonomics was questionable in respect of the low level of usage.
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Actitud Frente a la Salud , Comportamiento del Consumidor , Adhesión a Directriz , Salud Laboral , Postura , Ergonomía , Femenino , Humanos , Entrevistas como Asunto , Masculino , Encuestas y Cuestionarios , Suecia , Interfaz Usuario-ComputadorRESUMEN
Audiological testing, interviews and exposure measurements were used to collect data on the health effects of styrene exposures in 313 workers from fiberglass and metal-product manufacturing plants and a mail terminal. The audiological test battery included pure-tone audiometry, distortion product otoacoustic emissions (DPOAE), psychoacoustic modulation transfer function, interrupted speech, speech recognition in noise and cortical response audiometry (CRA). Workers exposed to noise and styrene had significantly poorer pure-tone thresholds in the high-frequency range (3 to 8 kHz) than the controls, noise-exposed workers and those listed in a Swedish age-specific database. Even though abnormalities were noted on DPOAE and CRA testing, the interrupted speech and speech recognition in noise tests were the more sensitive tests for styrene effects. Further research is needed on the underlying mechanisms to understand the effects of styrene and on audiological test batteries to detect changes in populations exposed to solvents.
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Trastornos de la Audición/epidemiología , Audición , Ruido en el Ambiente de Trabajo/efectos adversos , Exposición Profesional/efectos adversos , Estireno/toxicidad , Adulto , Audiometría , Estudios de Casos y Controles , Bases de Datos como Asunto , Femenino , Encuestas Epidemiológicas , Trastornos de la Audición/etiología , Humanos , Entrevistas como Asunto , Masculino , Persona de Mediana Edad , Emisiones Otoacústicas Espontáneas , Encuestas y Cuestionarios , Suecia/epidemiología , Reino Unido/epidemiologíaRESUMEN
Optical techniques for real-time full-penetration monitoring for Nd:YAG laser welding have been investigated. Coaxial light emission from the keyhole is imaged onto three photodiodes and a camera. We describe the spectral and statistical analyses from photodiode signals, which indicate the presence of a full penetration. Two image processing techniques based on the keyhole shape recognition and the keyhole image intensity profile along the welding path are presented. An intensity ratio parameter is used to determine the extent of opening at the rear of a fully opened keyhole. We show that this parameter clearly interprets a hole in formation or a lack of penetration when welding is performed on workpieces with variable thicknesses at constant laser power.
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We describe a closed-loop control system ensuring full penetration in welding by controlling the focus position and power of a 4-kW Nd:YAG laser. A focus position monitoring system was developed based on the chromatic aberration of the focusing optics. With the laser power control system we can determine the degree of penetration by analyzing the keyhole image intensity profile. We demonstrate performance in bead-on-plate welding of Inconel 718 and titanium. The focus control system maintained a focal position on tilted and nonflat workpieces, and the penetration monitoring technique successfully controlled the laser power to maintain the full-penetration regime in the presence of linear and step changes of thickness. Finally we discuss the performances and the limits of the systems when applied to a realistic complex aerospace component.
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Styrene exposure and color vision for 108 workers (21-65 years) was studied at Swedish reinforced plastic plants. Acute exposure was measured at work. Data on past exposures and personal background data were collected by questionnaire. Current exposure varied between 0.3 and 96mg/m(3). Cumulative past exposures varied from 18 to 4455mg years/m(3), and an index of lifetime weighted average exposure (LWAE) varied from 5 to 129mg/m(3). Color vision was tested using the Lanthony D15 desaturated panel binocularly without prior training in conditions with ample light (1400lx). Color vision was slightly correlated to LWAE (r=0.188, p=0.052). Workers were divided into two exposure groups according to LWAE. Analyses of variance revealed effects on the Vingrys' color vision confusion index (F=6.04; p=0.016) and total error (F=6.296; p=0.014). This study thus indicates that styrene exposure even at levels below the current Swedish OEL of 20mg/m(3) may affect color vision negatively.
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Biochemical markers for the circadian rhythm were studied in patients treated at the ICU (intensive care unit) of two regional hospitals. A normal rhythm is characterized by a relatively higher melatonin and a lower cortisol excretion at night. Disturbances affect sleep, mood and cognitive performance. All urine excreted between 07:00 and 22:00 hours (day) and between 22:00 and 07:00 hours (night) was collected and sampled throughout the entire ICU period (median, 10 days) in 16 patients for the excretion of 6-SMT (6-sulphatoxymelatonin), which is a metabolite of melatonin, and free cortisol. The overall excretion of 6-SMT was slightly lower and the cortisol excretion higher than reported for healthy reference populations. Mechanical ventilation was associated with a markedly lower 6-SMT excretion (median, 198 ng/h) compared with periods without such help (555 ng/h; P<0.0001), whereas infusion of adrenergic drugs increased the 6-SMT excretion (P<0.01). Five patients (31%) showed a virtually absent melatonin excretion for 24 h or more. The diurnal rhythms were consistently or periodically disturbed in 65% and 75% of the patients. These alterations cannot be explained by excessive exposure to light at night. In conclusion, there was hyposecretion of melatonin during mechanical ventilation, an overall high cortisol excretion and a disturbed diurnal rhythm of both of these hormones in most patients treated in two ICU departments.
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Unidades de Cuidados Intensivos , Melatonina/análogos & derivados , Melatonina/metabolismo , Respiración Artificial , Adulto , Anciano , Anciano de 80 o más Años , Ritmo Circadiano/fisiología , Femenino , Humanos , Hidrocortisona/orina , Tiempo de Internación , Iluminación , Masculino , Melatonina/orina , Persona de Mediana EdadRESUMEN
The beliefs and attitudes regarding the risk of hearing loss and their impact on hearing protector use were investigated among Swedish workers. A questionnaire, developed by the US National Institute for Occupational Safety and Health (NIOSH), was used. The study objective was to assess workers' attitudes towards using hearing protection devices (HPDs) and to enhance the ability of workers to protect themselves from occupational hearing loss. Ninety-five per cent of the respondents were aware that loud noise could damage their hearing, 90% considered that a hearing loss would be a serious problem, and 85% believed that HPDs could protect their hearing. However, lower percentages of workers always used the HPDs when they were noise-exposed. Fifty-five per cent of the workers indicated that they could not hear warning signals when using HPDs, and 45% of the workers indicated that they considered HPDs to be uncomfortable. These issues must be addressed to make HPD use more effective.
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Dispositivos de Protección de los Oídos , Conductas Relacionadas con la Salud , Conocimientos, Actitudes y Práctica en Salud , Pérdida Auditiva Provocada por Ruido/psicología , Ruido/efectos adversos , Enfermedades Profesionales/psicología , Pérdida Auditiva Provocada por Ruido/epidemiología , Pérdida Auditiva Provocada por Ruido/prevención & control , Humanos , Análisis Multivariante , National Institute for Occupational Safety and Health, U.S. , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/prevención & control , Factores de Riesgo , Encuestas y Cuestionarios , Suecia/epidemiología , Estados UnidosRESUMEN
Audiometry and exposure measurements were conducted on workers from fiberglass and metal products manufacturing plants and a mail distribution terminal (N = 313). Workers exposed to noise and styrene had significantly worse pure-tone thresholds at 2, 3, 4, and 6 kHz when compared with noise-exposed or nonexposed workers. Age, noise exposure, and urinary mandelic acid (a biologic marker for styrene) were the variables that met the significance level criterion in the multiple logistic regression. The odds ratios for hearing loss were 1.19 for each increment of 1 year of age (95% confidence interval [CI], 1.11-1.28), 1.18 for every decibel >85 dB(A) of noise exposure (95% CI, 1.01-1.34), and 2.44 for each millimole of mandelic acid per gram of creatinine in urine (95% CI, 1.01-5.89). Our findings suggest that exposure to styrene even below recommended values had a toxic effect on the auditory system.
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Pérdida Auditiva/etiología , Ruido en el Ambiente de Trabajo/efectos adversos , Exposición Profesional/efectos adversos , Estireno/efectos adversos , Adulto , Análisis de Varianza , Audiometría , Estudios de Casos y Controles , Creatinina/orina , Femenino , Pérdida Auditiva/epidemiología , Humanos , Modelos Logísticos , Masculino , Ácidos Mandélicos/orina , Persona de Mediana Edad , Exposición Profesional/análisis , Prevalencia , Estireno/análisis , Suecia/epidemiologíaRESUMEN
The paper presents a summary of the literature published until December 2000 on effects from some industrial chemical exposures on color perception, as well as short descriptions of the tests applied. Several different tests have been used to study acquired alterations of color vision. These changes are frequently found in the blue-yellow axis. Many of the tests were originally designed to detect congenital alterations in the red-green axis, and thus have relatively low sensitivity when studying chemically induced deficits in color perception. At present, the Lanthony D15-desaturated panel seems most suitable for application in industrial settings, since it is clearly the most sensitive and easily administered test. Color vision seems to be a physiological function very sensitive to several chemicals. The potency of industrial chemicals to induce color vision deficiencies has often been investigated during the last two decades. The chemicals most frequently studied are different solvents and mercury. Pronounced effects on color perception have been reported following chronic exposure to organic solvents such as styrene, carbon disulphide, perchloroethylene, n-hexane and solvent mixtures, and to organic as well as inorganic mercury. The effect of occupational toluene exposure seems not as well established, since only slight effects and several negative studies have been reported. For some of these compounds the effect on color vision has been further established through the finding of clear dose-effect relationships. In a few cases, even acute exposure situations, e.g. exposure to toluene for a few hours or acute alcohol intake, seem to affect color perception. Follow-up studies are needed to investigate the possible reversibility of effects in relation to discontinued or reduced exposures.
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Pruebas de Percepción de Colores/estadística & datos numéricos , Defectos de la Visión Cromática/inducido químicamente , Exposición Profesional/efectos adversos , Compuestos Orgánicos/toxicidad , Pruebas de Percepción de Colores/métodos , Defectos de la Visión Cromática/diagnóstico , Defectos de la Visión Cromática/epidemiología , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Humanos , Exposición Profesional/estadística & datos numéricosRESUMEN
This paper presents data on visual functions (visual acuity, contrast sensitivity, and several tests of color vision), in a group of 199 non-exposed healthy subjects with an even distribution over the age range 18-65 years, and sex. Although subjects with obvious congenital color vision deficiencies were removed from the analyses (four males), females were superior to males on several of the color vision tests applied. Age influenced visual acuity and contrast sensitivity, while color discrimination was less affected. Correlations between functions of the right and the left eye in the individual subjects were rather low, ranging from 0.40 to 0.73. Correlations between visual acuity and contrast sensitivity on the one hand and color discrimination ability on the other hand were still lower (r < 0.20). These low correlations between functions in the two eyes support the need for testing each eye separately.