According to Dr Mackay psycho-social factors are at least as important as physical characteristics of workplace in influencing health and well being. Herewith a 10 line synopses of the author’s views:
It needs to be understood that, with reference to the workplace, psycho-social factors and physical characteristics are equally important. It is imperative for health and safety managers to be aware of the psycho-social factors associated with Visual Display Terminals (VDT) and it must be understood that serious problems can occur if work/workstations involving VDT’s are inappropriately designed. Sociotechnical, social contact, natural breaks, unfamiliar cognitive demands and qualitative aspects of job design must be taken into account and investigators should utilize research to evaluate cause-effect relationships. VDT’s related work will continue to be a problem for health practitioners if inappropriate design is not addressed.
According to Robert Snook, musculoskeletal injuries in the workplace continue to be the leading cause of disability in the developed countries. Herewith a 10 line synopses of the author’s view:
Musculoskeletal injuries are still one of the major causes of work related injuries and trauma in the workplace. Effective testing and selection of workers will indeed assist with limiting the effects of these trauma’s or disabilities. Controls must be put in place to reduce injuries related to musculoskeletal trauma, these controls can include: pre-placement testing, training, management of ergonomics, appropriate treatment and enlightened management.
In order for the management and control of musculoskeletal injuries to pay dividends, it is important to ensure that pre-placement and the selection of workers are given priority, as this method has proven to be the most effective approach to limiting the trauma caused to workers through musculoskeletal disorders.
Cumulative Trauma Disorder (CTD) with reference to whole body vibration and ergonomics of driving occupants (earthmoving equipment).
Cumulative Trauma Disorder or CTD can be described as a strain related injury or trauma resulting from repetitive motions, excessive force, poor posture or no rest breaks. Poor ergonomics can be a contributing factor to CTD as the worksite, job tasks, work habits or body mechanics are often not assessed to identify risks related to CTD and in the absence of identified risks, no mitigation actions to reduce the impact of CTD in the workplace will be in implemented. This type of injury or trauma occurs when employees are required to work harder and/or at a greater level that was originally prepared for, immediate impact to the body might be limited, however, repeated exposure to the trauma will most definitely lead to CTD. Musculoskeletal disorders, like whole body vibration is a discipline that is interchangeable with CTD.
Whole body vibration or WBV is mechanical vibration that is generally transmitted into the body through the seat (of road vehicles or plant equipment) or the feet of a person standing on a vibrating surface (like a floor or a suspended platform). Studies have shown that long term exposure to whole body vibration can cause musculoskeletal systems in the lower back, neck, shoulders and knees serious injury or trauma.
As we are all aware, back disorders are the most common form of ill health at work. During 2005/2006 two million people in the UK suffered from ill health and half of these suffered from musculoskeletal disorders related to WBV. These disorders could have lead to serious cumulative trauma related illnesses.
The exposure to WBV is a potential hazard for operators of earthmoving equipment, the driving of these vehicles expose the driver and occupants to WBV, this may include shocks and jolts that are believed to increase the likelihood of pain in the lower back. The operators of older equipment have reported a much higher percentage of missed work and doctor’s visits due to musculoskeletal symptoms than those using new equipment.
Operators of construction vehicles perform 4 main tasks:
- Building roads, bridges, tunnels and dams
- Construction of buildings a plants
- Removal of earth and grading of earth
- Constructing of drainage systems
“Whole – body vibration and postural stress among operators of construction equipment “ – N Kumar Kittusamy and Bryan Buchlolz, A Literature review.
It is very important and imperative to the health and safety of workers that the hazards associated with WBV are assessed and that information is gathered to assist in the designing of better working conditions for these workers.
The International Standard ISO 2631:1 : 1997 is commonly used as a benchmark for the management of WBV. This standard defines symbols, coordinates systems and nominates acceleration as a primary quantity by which vibration is to be expressed for evaluation. This standard also supplies instructions regarding the measurements, locations, signal conditioning and duration of the measurements for exposure to WBV. Clause 7 of this standard provides guidance for the evaluation of health effects on workers related to vibration, with specific reference to Annex B of the standard.
During the evaluation of the hazards related to WBV the following must be taken into account:
Critically important to the management of WBV in the construction industry is the identification of hazards and assessment of the risks associated with driving construction vehicles for a living.
Key aspects of a risk assessment should include:
- the identification of the risks;
- decisions must be made as to which employees are actually at risk;
- process changes must be implemented to reduce vibration risk;
- control measures must be put in place;
- the effectiveness of the controls must be monitored;
- employees must form part of the health surveillance program;
- the risk assessment must be reviewed on a regular basis.
Persons performing these risks assessments must have sufficient training, experience and skill in the operating of construction equipment. Employees involved in the drafting of the risk assessment must have the ability and skill to share their knowledge and findings with the employees to ensure that they understand the risks related WBV in their workplace, also important is that the drafters of these important documents must have the knowledge and experience to make the correct decisions regarding the monitoring and revision of the risk assessment.
In order to perform a comprehensive risk assessment that will address all the risks and offer applicable and workable mitigation measures, it is important that we start by assessing the actual vibration level that the employee is exposed to. Vibration levels are generally measured on and below the suspension seat within the cab of the vehicle and the representative period for the measurements are the operator’s working day and daily exposure.
A common misconception is that a really spongy seat is the best option for the elimination of WBV, the driver however starts becoming uncomfortable after a while as he starts to move the seat to gain a suitable posture. The seat of a construction vehicle must be firm and offer good support, the seat must also be adjustable to change the direction of the vibration as well as the direction of the human body. Gustafson-Sӧderman (1987) evaluated what effect seats with adjustable sitting angles and it was found that the highest estimated discomfort values were received from operators using ordinary seats and the lowest discomfort values were from the use of seats with an adjustable sitting angle.
The cab fit must also be taken into account when measurements are taken and this includes the seat, steering wheel, hand control and the right and left side. The aim of an anthropometric assessment is to identify any mismatches between the cab dimensions and the anthropometric dimensions of the general population.
Posture can be videoed for later analysis, this is be a very handy tool that can give an action level with an indication for urgency of implementation of mitigation measures. This importance of assessing the postural requirements of construction vehicle operators to WBV has been echoed in recent literature. Awkward posture during the operation of construction vehicles can result in the increased risk of pain, injury or fatigue and these risks are increased by poor visibility of the task, limited room in the cab, excessive forces required to operate the pedals and improper seat design. Recent studies have shown that the risk of WBV and therefore the risks of musculoskeletal disorders can be limited by the use of big mirrors, swivel seats and seats with an adjustable sitting angle.
What can be done to manage WBV in the construction industry?
- Ensure that Risk Assessments are comprehensive and that the communication related to the assessment is effective.
- Health Surveillance must be performed and the frequency of assessments must be placed on a schedule.
- Education and awareness campaigns must be put in place to ensure that drivers are trained and made aware issues like good posture and seating within the cab of the vehicle.
- Machinery must be placed on a maintenance program to ensure that they are in a serviceable condition at all times, old seats must be replaced, large mirrors must be fitted and hydraulics must be checked.
Studies indicate that operators of construction equipment are definitely afflicted by musculoskeletal injuries related to WBV and the qualification of vibration and postural requirements in practical settings are important for the development of better comprehension of the exposure levels that are present in different construction equipment performing a variety of tasks.
- “Whole Body Vibration and postural stress among operators of construction equipment: A literature review” – Kumar Kittusamy N and Buchlotz B
- “Workplace Ergonomics” – Cris A Rowan (BScOT, BScBi) – Registered Occupation Terapist
- http://www.be-ge – viewed 15 August 2012 – Whole body vibration and Ergonomics of Driving Occupants
- “How on earth moving equipment can ISO 2631.1 be used to evaluate whole body vibration?” – 2012 – Robin Burgess-Limerick and Maslen K
- “Whole-body vibration and ergonomics of driving occupants”, Darby AM, Pitts P, Heaton R, Mole M, Health and Safety Executive – 2012