2011-10-01 12:00 - Messages

Handle types on the commonly used grass trimmer reaches the exposure limit value for daily vibration exposure.

The portable petrol driven grass trimmer is identified as a type of machine whose operator can be subjected to large magnitude of hand-arm vibration. The vibration total level on the handle of grass trimmer of 11.30 m/s2 was measured, and it has reached the exposure limit value of 5.0 m/s2 for daily vibration exposure A(8). Operators were not fully aware of the level of vibration. Different prototype handles were tested; one that is made of heavier material results in the lowest hand-arm vibration. The new handle has significantly reduced the vibration total value by 76% compare with the existing commercial handle. Large numbers of workers are employed to perform grass trimming job in many developing countries.

Source: The design and development of suspended handles for reducing hand-arm vibration in petrol driven grass trimmer. Ko Y.H., Ean O.L. and Ripin Z.M.; International Journal of Industrial Ergonomics; Volume 41, Issue 5, September 2011, Pages 459-470.


Hand-arm vibration of horticultural machinery Part 2

The work described in this report assesses the standard test for hedge trimmers defined in BS EN ISO 10517:2009 for repeatability and ease of use and where possible for reproducibility (by comparing machine manufacturers’ declared vibration against HSL measurements to the same standardised procedures). It also
assesses the validity of the measurement techniques adopted in the vibration emission test, investigates some of the factors which are likely to influence the results of the test and compares the vibration emission values with vibration magnitudes measured under real operating conditions.

The report concludes that for three of the four hedge trimmers the vibration emissions slightly overestimate the upper quartile. For the fourth hedge trimmer the upper quartile is overestimated by approximately 50%. Placing of the vibration emissions during normal intended use of the machinery in satisfactory rank
order cannot be assured by comparing the vibration emissions determined according to the test code, BS EN ISO 10517:2009. The test code inconsistently represents workplace vibration.

Source : http://www.hse.gov.uk/research/rrpdf/rr894.pdf

Reducing Noise Hazards for Call and Dispatch Center Operators

 Workers at call and dispatch cen­ters may suffer health risks asso­ciated with high noise levels from their headsets. The NIOSH evaluations did not reveal hearing loss problems among call center operators and dispatch­ers that can be directly attributed to noise exposures from their headsets or the surrounding environment. Howev­er, most workers interviewed reported various symptoms often associated with prolonged exposure to high noise levels. Symptoms included ringing in their ears, headaches, irritability, increased tension, and fatigue. There are international standards on office noise for comfort, and measuring sound levels but not one with exposure limits specific to Call Centers. The International Standard ISO 11904-1, 11904-2 describes the proper way to measure the noise levels through the headsets using an acoustical head fixture. To conduct a "sound test" at facilities, the guidelines in these standards or their tests should be followed to be valid. The National Insti­tute for Occupational Safety and Health (NIOSH) has also developed recommendations to protect against hearing dam­age and other adverse health effects.

 Source: Reducing Noise Hazards to Call and Dispatch Center Operators. Workplace solutions, DHHS (NIOSH) Publication No. 2011-210, September 2011.



Pneumatic nail guns produce loud “impulse” noise peaks in a range from 109 to 136 dBA.

Pneumatic nail guns produce short (less than a tenth of a second in du­ration) but loud “impulse” noise peaks: one from driving the nail and one from exhausting the air. Most nail gun manufacturers recommend that users wear hearing protection when operating a nailer.  Available information indicates that nail gun noise can vary depending on the gun, the work piece, air pressure, and the work setting. The type of trigger system does not appear to affect the noise level. Peak noise emission levels for several nailers ranged from 109 to 136 dBA. These loud short bursts can contribute to hearing loss. Employers should provide hearing protection in the form of earplugs or muffs and ensure that they are worn correctly. Employers should also ask about noise levels when buying nail guns—studies have identified ways to reduce nail gun noise and some manufacturers may incorporate noise reduction features. 

The NIOSH and OSHA limit for impulse noise is 140 decibels: above this level a single exposure can cause instant damage to the ear. NIOSH recommends that an 8-hour exposure should not exceed 85 dBA and a one-second exposure should not exceed 130 dBA without using hearing protection.

Source:  Nail Gun Safety: A Guide for Construction Contractors. DHHS (NIOSH) Publication Number 2011-202, OSHA Publication Number 3459-8-11


NIOSH thinks of investigating further pain caused by tattoo gun vibration.

A full time tattoo artist posted a question on NIOSH Science Blog (#22): «i have been getting sever numbness and tingling in my finger it will last up to two to three days on times i am getting concerned about the effects the vibration of the tattoo machine may be causing».

Amy Mobley and Renguang Dong of NIOSH answered: «The tattoo gun seems similar to some dental tools and it may generate high frequency vibration. At higher frequencies, the vibration-induced problems are mainly in the hand and fingers, such as finger tingling, numbness, pain, and white finger. » They said that they are considering investigating further this topic to try to better understand any long-term effects and what tattooists can do to avoid these problems. Any useful additional information or recommendations will be posted.

Source: NIOSH Science Blog, Safety and Health for Tattooists and Piercers. Blog # 22, Posted 6/22/11, Renguang Dong, Ph.D, NIOSH Health Effects Laboratory Division.


Increased absence rates are found in shared and open-plan offices.

The aim of this study was to examine whether shared and open-plan offices are associated with more days of sickness absence than cellular offices. Sickness absence was significantly related to having a greater number of occupants in the office (P<0.001) when adjusting for confounders. Compared to cellular offices, occupants in 2-person offices had 50% more days of sickness absence, occupants in 3–6-person offices had 36% more days of sickness absence and occupants in open-plan offices (>6 persons) had 62% more days of sickness absence. The study concludes that occupants sharing an office and occupants in open-plan offices (>6 occupants) had significantly more days of sickness absence than occupants in cellular offices.


This study is cross-sectional and cannot explain the mechanisms behind the increased sickness absence rates in shared and open-plan offices. However, the literature suggests some explanations. One explanation could be that increased absence rates in shared and open-plan offices are caused by higher exposure to noise in these offices. The most prevalent complaint in open-plan offices is noise annoyance, with ringing phones and other peoples’ conversation being the most annoying sources of noise. No known studies to the researchers have related noise to sickness absence solely in office buildings.


Source: Sickness absence associated with shared and open-plan offices – a national cross sectional questionnaire survey. Pejtersen JH, Feveile H, Christensen KB, Burr H; Scand J Work Environ Health 2011;37(5):376-382 ; doi:10.5271/sjweh.3167


Hand-arm vibration of horticultural machinery: Part 1

In recent years there have been many cases of HAVS being reported for people who work in agriculture, horticulture and landscape gardening. HSE/HSL does not currently hold much information on vibration exposures in these areas of work.
The work described in this research report assesses the standard test defined in BS EN 836:1997 (incorporating amendments Nos. 1 to 3) for repeatability and ease of use and where possible for reproducibility (by comparing machine manufacturers' declared vibration against HSL measurements to the same standardised procedures).

Source : http://www.hse.gov.uk/research/rrpdf/rr884.pdf

A hybrid of task-based and subjective rating of noise estimates is more accurate than exposure estimates from individual assessment techniques.

Any exposure estimation technique has inherent strengths and limitations. In an effort to improve exposure estimates, this study developed and evaluated the performance of several hybrid exposure estimates created by combining information from individual assessment techniques.  Three single exposure assessment techniques [trade mean (TM), task-based (TB), and subjective rating (SR)] were used to estimate exposures for each subject. Hybrid techniques were then developed which incorporated the TM, SR, and TB noise exposure estimates via arithmetic mean combination, linear regression combination, and modification of TM and TB estimates using SR information. Exposure estimates from the single and hybrid techniques were compared to subjects' measured exposures to evaluate accuracy. Hybrid noise exposure estimates performed better than individual estimates, and in this study, combination of TB and SR estimates using linear regression performed best.

Source: Improving Exposure Estimates by Combining Exposure Information. Richard L. Neitzel, William E. Daniell,  Lianne Sheppard, Hugh W. Davies and Noah S. Seixas. Ann Occup Hyg (2011) 55 (5): 537-547. doi: 10.1093/annhyg/mer011 First published online: April 5, 2011 .


La prothèse auditive fonctionnant à l'énergie solaire pourrait être d'une grande aide pour l'Afrique

L'appareil à énergie solaire a été conçu par Andrew Carr, un ingénieur mécanicien de Cambridge. Pour fonctionner, la prothèse doit être portée près de l'oreille, mais n'a pas besoin d'être placée à l'intérieur.

Le dispositif possède une pile solaire interne, et peut être attaché à un collier ou à un chapeau de façon à être porté près de l'oreille. "Cela qui s'intègre mieux à la culture locale que les prothèses roses et légères pour Caucasiens qui ont déjà été données", souligne Andrew Carr.

Source : Médecine: des innovations au secours des plus pauvres . Le Nouvel Observateur, Publié le 13-09-11.


À noter que des essais avaient eu lieu auparavant - L'innovation

au Botswana : Le Centre technologique du Botswana. Le Magazine de l'OMPI 2005 Numéro 4/2005



Support and determination to get accustomed to hearing protector use are important factors in hearing conservation for musicians.

Despite a high level of sound exposure and a fairly large selection of earplugs available, musicians have often been reported to use personal hearing protectors only seldom. Musicians reported that earplugs hampered listening to their own and their colleagues' playing; earplugs affected either timbre or dynamics, or both. Additionally, several reasons related to discomfort of use were itemized.

The research therefore tested subjects. With the REAT procedure, the values obtained in sound field were relatively close to the manufacturer's nominal specifications. Then, subjects were tested with Bikisy audiometry to find out whether a sweeping signal would bring detailed information on earplug attenuation. Mean attenuation was found to be somewhat closer to the nominal attenuation of the ER-9 and ER-15 earplugs up to about 1 kHz, whereas REAT measurements in sound field revealed more even attenuation at frequencies between 1 and 6 kHz.

No significant association was found between earplug attenuation properties and earplug use.


Source: Symphony orchestra musicians' use of hearing protection and attenuation of custom-made hearing protectors as measured with two different real-ear attenuation at threshold methods. Huttunen, KH,  Sivonen VP,  Poykko VT ; Noise Health. 2011 Mar-Apr; 13(51):176-88.


United Kingdom: Council prosecuted after worker loses movement in hands.

Cheshire East Council was prosecuted by the Health and Safety Executive (HSE), United Kingdom, after a 56-year-old mechanic developed a severe form of hand arm vibration syndrome. Since 1984, the worker regularly used heavy-duty vibrating equipment, including pneumatic drills and hand-held grinders.

The investigation inspector at HSE explained:  "The worker was first diagnosed as developing hand arm vibration syndrome in 2005 but the council failed to take any significant action for nearly four years to stop the condition getting worse. The council should have limited the amount of time he spent using vibrating equipment, or provided alternative tools. Instead, he was allowed to continue with his job without any changes. If this action had been taken, the worker's condition could have been prevented from becoming serious. Instead, he has suffered a permanent loss of movement to his hands."

Cheshire East Council was fined £5,300 and ordered to pay £5,860 towards the cost of the prosecution. Cheshire East is the third largest unitary authority in the North West of UK.


Source: Council prosecuted after worker loses movement in hands. Health and Safety Executive, Release No: HSE/NW/73CheshireEast; 21 January 2011.


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