2012-10-01 12:00 - Messages

Principaux risques physiques à l'origine de troubles lombalgiques chez les opérateurs d'engins mobiles : revue de littérature

Les enquêtes épidémiologiques démontrent un risque accru de lombalgie chez les opérateurs d'engins mobiles travaillant en position assise. Pour prévenir ce risque, l'INRS et ses homologues internationaux cherchent à développer une méthode d'évaluation du risque vibratoire intégrant l'ensemble des contraintes physiques auxquelles des opérateurs d'engins vibrants peuvent être exposés. Les efforts portent sur l'apport de connaissances nouvelles concernant la quantification ainsi que l'évaluation de la sévérité de la posture et des mouvements d'un conducteur dans un environnement vibrant (modélisation, épidémiologie, protocole d'évaluation, etc.).  Aujourd'hui, les préventeurs n'en sont qu'à l'étape initiale de spécification des grandeurs descriptives de la posture et de l'environnement ergonomique du conducteur assis. L'objectif de cet article est de présenter, à travers une revue de littérature, les connaissances actuelles sur les principaux risques physiques à l'origine de troubles lombalgiques chez les opérateurs d'engins mobiles. Les grandeurs de référence qui déterminent la position et les mouvements du corps sont ensuite détaillées et illustrées par des mesures effectuées à l'aide d'un dispositif spécifique adapté au poste de conduite d'engins mobiles.

Source : Amari, M. Opérateurs d'engins mobiles. Vers une prise en compte de la posture dans l'évaluation du risque vibratoire. INRS, HST, Note documentaire • ND 2359. http://www.hst.fr/inrs-pub/inrs01.nsf/IntranetObject-accesParReference/HST_ND%202359/$File/ND2359.pdf


Even a Dummy Knows October is Protect Your Hearing Month

Meet Nick.  Nick is a training mannequin who helps NIOSH teach young people and their families about preventing noise-induced hearing loss.  Hearing loss can result from working around noise–even non-powered hand tools–without wearing proper hearing protection. It is not uncommon for a 25 year-old farmer or carpenter to have the hearing of a 50 year-old.  In fact, 33% of all people who are exposed to hazardous noise at work will develop noise-induced hearing loss. You don’t have to work on a farm or at a factory to be at risk; common noise sources around your house – such as lawnmowers, power tools, and music systems – can be hazardous to your hearing.  It is the sum of all of your exposures to sound throughout the day and evening that add together to damage hearing when that total becomes excessive. Even the young are at risk.  In the general population, approximately 15% of those between ages 6 and 19 show signs of impaired hearing.[i]  One study found that over 30% of high school boys who live or work on a farm have hearing loss[ii]. We need to protect this and the next generation of workers.

Source : http://blogs.cdc.gov/niosh-science-blog/2012/10/protect-hearing/

Workers in the Mining, Manufacturing, and Construction industries need better engineering controls for noise

Twenty-two million workers are exposed to hazardous noise in the United States. The purpose of this study is to estimate the prevalence of hearing loss among U.S. industries. 2000–2008 audiograms for male and female workers ages 18–65, who had higher occupational noise exposures than the general population showed that 18% of workers had hearing loss. When compared with the Couriers and Messengers industry sub-sector, workers employed in Mining, Wood Product Manufacturing, Construction of Buildings and Real Estate and Rental and Leasing had higher risks for hearing loss. Workers in the Mining, Manufacturing, and Construction industries need better engineering controls for noise and stronger hearing conservation strategies. More hearing loss research is also needed within traditional “low-risk” industries like Real Estate.

Source : Elizabeth A. Masterson, SangWoo Tak, Christa L. Themann, David K. Wall, Matthew R. Groenewold, James A. Deddens, Geoffrey M. Calvert. Prevalence of hearing loss in the United States by industry. Am. J. Ind. Med, 2012. Article first published online: 5 JUL 2012. http://dx.doi.org/10.1002/ajim.22082

In Ireland, the average bar employee daily noise exposure is almost 4 times more than the accepted legal limit

Due to the transposition of the EU Directive 2003/10/EC into Irish Law, the entertainment sector was obligated to comply with the requirements of the Safety, Health and Welfare at Work (General Application) Regulations 2007, Chapter 1 Part 5: Control of Noise at Work since February 2008. Compliance with the Noise Regulations was examined in 9 nightclubs in Ireland. The typical daily noise exposure of 19 bar employees was measured using 2 logging dosimeters and a Type 1 fixed position sound level meter. Physical site inspections identified nightclub noise control measures. Interviews and questionnaires were used to assess the managers and employees awareness of the noise legislation. The average bar employee daily noise exposure (L EX, 8h) was 92 dBA, almost 4 times more than the accepted legal limit. None of the venues examined were fully compliant with the requirements of the 2007 Noise Regulations, and awareness of this legislation was limited.
Source: Aoife C Kelly, Sara M Boyd, Gary T. M. Henehan, Gordon Chambers. Occupational noise exposure of nightclub bar employees in Ireland. Noise&Health, 2012, Vol. 14, Issue 59, p.148-154.



Classrooms with shorter reverberation times lead to a much better signal-to-noise ratio while requiring less vocal effort from teachers

The study presented here is the most extensive, systematic study to examine the impact of reducing reverberation in a working school environment. By installing varying acoustic treatments in three similar classrooms it has been possible to investigate the true effects of different acoustics in occupied schoolrooms. The three classrooms, plus an untreated room, were compared both objectively through acoustic measurements and subjectively through surveying the opinions of pupils, teachers and other adults. The results demonstrate conclusively the benefits to all of improving the acoustic environment.

Source: David Canning, Adrian James. The Essex Study- Optimised classroom acoustics for all. The Association of Noise Consultants.May 2012.
Voir aussi : http://www.acousticbulletin.com/EN/Ecophone_Essex_6ppA4_v8_LO_Singles.pdf

Six-degrees-of-freedom measurement to select operator seats based on industry specific field vibration characteristics

The purpose of this paper was to quantify in (6DOF) whole-body vibrations during the daily operating tasks of 5 commonly used mobile machines types used in the steel making and metal smelting industries. Elevated values were observed at the chassis for crest factors, peak running root mean squared accelerations, and vibration total values, resulting in ISO 2631-1 (1997) comfort predictions ranging from Uncomfortable to Extremely Uncomfortable. Vibration dominant frequencies were generally between 1 and 8Hz. A second peak which occurred at approximately 27 Hz was observed for each vehicle in almost all axes. Occurring at a frequency that has the potential to produce negative health effects, this second peak was probably caused by the engine idling or running at low speeds. Field vibration profiles from this study have been used as inputs to a 6DOF robot for use in a corresponding laboratory study designed to optimize seat selection thus allowing the steel making and other similar industries to select operator seats based on industry specific field vibration characteristics.

Source: Conrad, L. F., Oliver, M. L., Jack, R. J.,  Dickey, J. P. et T. Eger. Quantification of 6-degree-of-freedom chassis whole-body vibration in mobile heavy vehicles used in the steel making industry. Journal of low frequency noise, vibration and active control, vol. 31 no. 2, 2012, p. 85 – 104.

Industrial noise > 80 dBA, has a significant effect on salivary cortisol elevation

This study had 3 goals: (1) Assess and compare saliva cortisol concentrations in the morning and evening in normal work day and leisure day in industrial workers, (2) assess the relationship between industrial noise exposure and salivary cortisol concentrations, and (3) assess the possibility of using salivary cortisol as a possible marker of noise-induced stress. No significant difference was obtained for morning cortisol levels between leisure day and working day samples. But, for evening cortisol concentrations, a strong significant difference was noted leisure day and working day. The evening cortisol in the working day correlated significantly with noise exposure > 80 dBA. Our study revealed that industrial noise, with levels > 80 dBA, has a significant effect on salivary cortisol elevation.

Source: D Behzad Fouladi, Parvin Nassiri, E Mohammadreza Monazzam, Saeed Farahani, Gholamreza Hassanzadeh, Mostafa Hoseini. Industrial noise exposure and salivary cortisol in blue collar industrial workers. Noise&Health, 2012, vol. 14, issue 59, pp. 184-189.

Considerable differences in the transmissibility measurements of whole-body vibration without proper correction

Accurate measurements of human response to whole-body vibration are essential to any conclusions about the health risks, discomfort, and assessment of suspension systems in vibration environments. While accelerometers are traditionally considered the main measurement tools in whole-body vibration studies, their measurements become questionable when they are attached to inclined surfaces or when the motion has coupled components in multiple directions. Current measurement correction methodologies are subjective and limited to simple cases. A comprehensive correction methodology using inertial sensors was used in this work to quantify human response under single fore-aft, single-vertical, and multiple-axis whole-body vibration of twelve seated subjects with supported-backrest and unsupported-backrest upright posture. Vibration files of white noise random signals with frequency content of 0.5-12 Hz and vibration magnitude of 1.8 m/s2 RMS were used in the testing. The results have shown considerable differences in the transmissibility measurements without proper correction. The work presented has the potential to standardize experimentation in whole-body vibration and make measurements more accurate and defined across labs.

Source: Jonathan DeShaw and Salam Rahmatalla. Comprehensive measurement in whole-body vibration. Journal of low frequency noise, vibration and active control, Vol. 31 No. 2 2012, pp 63-74. http://multi-science.metapress.com/content/r521456hru051850/fulltext.pdf

Exposure of suspended cabin tractor semi trailer drivers exceeds the upper limit for an 8-h work day

This paper presents a study on whole body vibration analysis for drivers of tractor semitrailers. The tractor semitrailer, namely, a suspended cabin tractor semitrailer was considered for the present investigation. The important process parameters such as different speeds, different road surfaces and different loaded conditions with driver seat interface acceleration in X- longitudinal, Y transverse and Z-vertical axes were tested. The average running weighted root mean square accelerations obtained after conducting the experimental work were between 0.6265 and 1.5594 m/s2 at the driver seat interface in the translational axes. Based on the weighted acceleration the value was compared to ISO 2631-1:1997 to find the permitted exposure time of drivers. The acceleration suspended cabin tractor semi trailer drivers are exposed to exceeds the upper exposure limit for an 8-h work day as outlined in (ISO 2631-1:1997) [1] when they work continuously.

Source: P.Velmurugan, L.A.Kumaraswamidhas et K.Sankaranarayanasamy. Influence of road surfaces on whole body vibration for suspended cabin tractor semitrailer drivers. Journal of low frequency noise, vibration and active control, Vol. 31 No. 2 2012, p. 75 – 84.

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