2012-08-01 12:00 - Messages

Réduction des vibrations au poste de conduite des engins de chantier : Travailler sans secousse

Les conducteurs et opérateurs d'engins de chantier sont régulièrement exposés à des vibrations et chocs transmis à l'ensemble du corps par le siège et le plancher. Pour la plupart des engins, l'exposition est au-dessus de la valeur d'action définie par le décret n° 2005-746. Dans certains cas, la valeur limite peut être dépassée.
Ce guide introduit une démarche générale, pour réduire le risque vibratoire, qui est reprise en trois fiches spécifiques aux familles d'engins suivants :
. pelles et chargeuses-pelleteuses,
. chargeuses sur pneux et mini-chargeurs,
. tombereaux rigides et articulés.

Source : http://www.inrs.fr/accueil/produits/mediatheque/doc/publications.html?refINRS=ED%206130

The vibrotactile perception threshold changes were greatest after simultaneous exposure to both WBV and HAV

This article presents the results of laboratory tests on the combined effect of whole-body vibration (WBV) and hand–arm vibration (HAV). The reactions of subjects exposed to various combinations of vibration were recorded. The vibrotactile perception threshold (VPT) test identified changes caused by exposure to vibration. Ten male subjects met the criteria of the study. There were 4 series of tests: a reference test and tests after exposure to HAV, WBV, and after simultaneous exposure to HAV and WBV. An analysis of the results (6000 ascending and descending VPTs) showed that the changes in VPTs were greatest after simultaneous exposure to both kinds of vibration. The increase in VPT, for all stimulus frequencies, was then higher than after exposure to HAV or WBV only.


Source: Piotr Kowalski & Jacek Zając. Research on Simultaneous Impact of Hand–Arm and Whole-Body Vibration.  International journal of occupational safety and ergonomics , Volume 18 Number 1, 2012 59-66.
http://www.ciop.pl/26861.html

Characterization of Frequency-Dependent Responses of the Vascular System to Repetitive Vibration

Objective: Occupational exposure to hand-transmitted vibration can result in damage to nerves and sensory loss. The goal of this study was to assess the frequency-dependent effects of repeated bouts of vibration on sensory nerve function and associated changes in nerves. Methods: The tails of rats were exposed to vibration at 62.5, 125, or 250 Hz (constant acceleration of 49 m/s2) for 10 days. The effects on sensory nerve function, nerve morphology, and transcript expression in ventral tail nerves were measured. Results: Vibration at all frequencies had effects on nerve function and physiology. However, the effects tended to be more prominent with exposure at 250 Hz. Conclusion: Exposure to vibration has detrimental effects on sensory nerve function and physiology. However, many of these changes are more prominent at 250-Hz exposure than at lower frequencies.
Source : Krajnak, K.; Miller, G. R.; Waugh, S.; Johnson, C.; Kashon, M.L. Characterization of Frequency-Dependent Responses of the Vascular System to Repetitive Vibration. Journal of Occupational & Environmental Medicine: August 2012 - Vol. 54 - Issue 8 - p 1010–1016.

http//dx.doi.org/10.1097/JOM.0b013e318255ba74

http://journals.lww.com/joem/Abstract/2012/08000/Characterization_of_Frequency_Dependent_Responses.17.aspx

 

L’effet d’occlusion est une source d’inconfort qui entraine une réduction du temps de port

Les bouchons d’oreille représentent la solution de protection auditive à court terme la plus utilisée en milieu de travail. Cependant, l’effet d’occlusion du canal auditif cause une modification de la perception de sa propre voix par le porteur et une amplification des bruits physiologiques. Il est donc une source d’inconfort qui entraine une réduction du temps de port.


Source : Martin K. Brummund, Petit, Y., Sagard, F., Laville, F. Modélisation de l’effet d’occlusion des protecteurs auditifs de type bouchons d’oreille. Travail et santé, juin 2012, vol 28, no 2.
http://www.travailetsante.net/Juin2012.html

Employers can take steps to reduce the risk of back over on worksites

Concerns are growing about the high number of deaths due to vehicles or equipment backing over workers. An OSHA standard for regulating backing operations does not exist, but employers can take proactive steps to reduce the hazard.
“There is some fatigue associated with [backing alarms] in that you hear the same sound over and over again, and it starts to lose its meaning,” said Steve Hawkins, assistant administrator at the Tennessee Department of Labor and Workforce Development. Back-up alarms are not necessarily directional – workers on the ground may have no idea where the alarm is coming from. On a worksite with several other types of noises and distractions, the alarm may not be heard or acknowledged at all. In seven back-over fatality cases that occurred between 2005 and 2010, an alarm was working but not heard by the struck worker, according to OSHA data. Sites that set up rules for locating Workers on foot and followed those rules were safer than sites that either did not establish rules or failed to follow them.
Source: Kyle W. Morrison. Reducing back over incidents. Safety+Health | June 2012. http://viewer.zmags.com/publication/fd02d42b#/fd02d42b/56

La participation du travailleur à l’évaluation environnementale du bruit a généré de nombreuses pistes d’amélioration

Pour identifier les possibilités de réduction des expositions, les principales sources de bruit et notamment les différents dysfonctionnements générateurs de ces niveaux sonores ont été repérés par des groupes de travail polycompétents composés de superviseurs, d’opérateurs et d’agents maintenance. La participation de l’opérateur à l’analyse causale des risques de son environnement a favorisé son implication active dans les actions sécurité générant de nombreuses pistes d’amélioration.
Source : Esteves, B., Blanche, V. Une démarche de mise en conformité  réglementaire de l’exposition au bruit des travailleurs. Archives des Maladies professionnelles et de l'Environnement, Volume 73, Issue 2, April 2012, p. 138–139.
http://www.sciencedirect.com/science/article/pii/S1775878512000720
http://dx.doi.org/10.1016/j.admp.2012.02.046

Une nouvelle norme pour mesurer l'acoustique de bureaux à aires ouvertes

L'ISO 3382-3:2012 spécifie les méthodes de mesurage des propriétés acoustiques des salles dans les bureaux ouverts avec mobilier. Elle décrit les modes opératoires de mesurage, l'appareillage nécessaire, la couverture requise et la méthode d'évaluation des données et de présentation du rapport d'essai.

Les résultats des mesurages peuvent être utilisés pour évaluer les propriétés acoustiques des salles dans les bureaux ouverts. L'ISO 3382-3:2012 est destinée à être utilisée pour les bureaux ouverts de moyennes et grandes dimensions.

Source : ISO. Acoustique -- Mesurage des paramètres acoustiques des salles -- Partie 3: Bureaux ouverts. 2012. 16 p. http://www.iso.org/iso/fr/home/store/catalogue_tc/catalogue_detail.htm?csnumber=46520 

Exploring how anthropometric, vehicle and workplace factors influence whole-body vibration exposures during on-farm use of a quad bike

The primary aim of this study is to determine whether a combination of body height, terrain and vehicle mechanical factors confound for the effect of body mass on WBV exposure while using a quad bike under normal rural working conditions. A seat pad mounted triaxial accelerometer and data logger recorded full work day vibration and shock data from 130 New Zealand rural workers. Personal, vehicle and workplace characteristics were gathered using a modified version of the Whole Body Vibration Health Surveillance Questionnaire. Whole-body vibrations were analysed in accordance with the ISO 2631-1 and ISO 2631-5 standards and it is presented as one hour vibration dose value in the Z-direction (1 h VDVZ). Body mass did not demonstrate any significant bivariate association (P > 0.20) with 1 h VDVZ. However BMI, body height, vehicle weight, sheep farm, dairy farm, 2 shock absorber solid axle rear suspension, flat farmland and engine capacity (cc) all demonstrated threshold bivariate associations (P ≤ 0.20) with 1 h VDVZ. Body mass, body height, 2 shock absorber solid rear axle suspension, and working on a sheep farm created the strongest multiple regression model explaining 16% of variance in VDVZ.Relevance to industry: The influence of driver's body mass on vibration exposure is strongly influenced by work environment and vehicle mechanical factors and this should be taken in to consideration for research that explores exposures and/or designing seating and suspension systems to attenuate vibration exposures in small on-farm vehicles.

Source : Milosavljevic, S. ; Mani, R.; Cury Ribeiro, D.;  Vasiljev, R.;  Rehn, B. Exploring how anthropometric, vehicle and workplace factors influence whole-body vibration exposures during on-farm use of a quad bike. International Journal of Industrial Ergonomics, vol. 42, no 4, July 2012, p. 392–396. http://dx.doi.org/10.1016/j.ergon.2012.04.004

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