Health and Safety: Exposure to Vibration - Assignment Example

Health and Safety (Exposure to vibration) Exposure to vibration can cause adverse health effects in workers i. Describe the nature of occupational vibration exposure and the health effects of exposure to vibration; provide researched examples of affected workers or groups of workers. Vibration Exposure to vibration by workers has not been viewed as a health hazard by many. Vibrations can be felt, but the determination of its harmful effects remains next to impossible. Vibration is defined as oscillations instigated mechanically from an object and originate from an equilibrium point. The oscillations may be regular or random, depending on the source. In determination of the health effects of vibration, overall pressure waves generated by the vibrating equipment must be measured. Vibration gets way into the body through the organ exposed to it. For example, vibration enters an operator of a chainsaw through the hands and arms. After prolonged use of the machine, the hands and arms get affected. Vibration is quantified by amplitude or intensity and frequency. Frequency is the number of cycles a vibrating object completes in a second, measured in hertz (Hz). Amplitude is the distance at which the object moves from a stationary position to the extreme position on either side, quantified in meters (m). Speed is used to determine the intensity of vibration and varies from zero to a maximum per cycle of vibration, quantified in meters per second (m/s). Acceleration measures the rate of change of speed with time, quantified in units of meters per second or meters per second squared. It increases whenever a vibrating object moves further from its statutory position. Resonance also plays critical role in the impact of vibration on the human body. Since each organ has its own resonant frequency, when an employee’s body is exposed to a vibration of similar frequency to a body organ, risks are greatly increased. Types of Vibration Exposure to hazardous levels of vibration is linked to adverse health outcomes. Some of the health problems caused by vibration are back pain, carpal tunnel syndrome and vascular disorders. Vibration injury is derived from outdoor activities such as farming, transportation, forestry, shipping and construction. Vibration exposure is divided into two categories: whole-body vibration (WBV) and segmental vibration or hand and arm vibration (HAV). Their sources differ as they affect different parts of the body, of different symptoms. a. Segmental vibration or hand-arm vibration This is a mechanical vibration transmitted to the human being through part or segment of the body, mostly the hands or arms. Hand-arm vibration causes permanent adverse health effects collectively referred to as hand-arm vibration syndrome (HAVS) and specific diseases like carpal tunnel syndrome. What is HAV? This term describes any kind of damage to blood vessels, nerves or muscles in the hands or arms caused by vibration from hand held tools or hand-guided machinery, or when employees hold materials under process by machinery. Most tools and processes vibrate at high levels that expose employees to risk of HAV. Some of these tools are concrete/road breakers, concrete pokers, sanders, disc cutters, hand held grinders and other rotary tools, hammer drills, jigsaws, polishers, sanders, chipping hammers, chainsaws, strimmers, brush cutters, hedge trimmers, leaf blowers, mowers, scrabblers or needle guns, pressure washers, and wood machining equipment among others. Exposure to HAV depends on several factors. These are The magnitude and frequency of vibration, The duration called trigger time and frequency of use, Pattern of exposure, including rest breaks, Manner of handling of machines, i.e. magnitude of grip, Surface area of hand exposure to vibration, Environment of working condition like awkward posture, Temperature of exposure, and Individual susceptibility. How does HAV affect health? Employees are exposed to a number of incurable injuries to arms, hands and even damage to blood circulatory system (the so-called vibration white finger), bones, muscles, and joints as well as sensory nerves. Symptoms related to the injuries are painful and/or disabling and may limit the jobs an affected person can do at work and in the social environment. Symptoms of HAV Appearance of body symptoms depends on individuals. For some people, the symptoms may appear after a few months of exposure and worsen with continued exposure. The physical symptoms are Finger blanching attacks. This implies that in cold and wet weather, fingers turn white and turn red and painful on recovery. Lack of sense to touch and detection of temperature. Tingling effect or numbness in fingers and or forearms Grip strength may reduce Manual dexterity is lost, and the employee cannot produce quality work like fastening of buttons. In the initial stages, a tingling sensation in the fingers and/or arms may be noticed by the employee. This is realised after a working day and may be accompanied by numbness. Later, the employee will experience periodic attacks whereby the fingers turn white when exposed to cold. In the earlier stages, the whiteness is experienced at the finger tips. Eventually, the whole finger and knuckles become white. In cold winter, the fingers turn pale, with loss of sense and often followed by intensive red flush and uncomfortable throbbing on recovery. As the condition worsens, the attacks not only take place at work but also during family and social activities and may last an hour. Gangrene may be a result of the disease in severe cases as the fingers turn blue or black. b. Whole-body vibration This refers to mechanical vibrations of low-frequency transmitted to the whole body or a number of body organs through a seat or floor when standing or entire body when leaning on a vibrating body. Human body has its own natural frequency. This applies to the body organs also and implies that they can resonate with vibration energy they receive that equals that of their natural frequencies. This has adverse health effects, and may worsen with chronic exposure. The frequency may range from 0.5 to 80Hz. Groups exposed to such vibration are truck operators, bus and tractor drivers and those working on vibrating floors (Kittusamy & Buchholz, 2004 pp.256-260). Health Effects of WBV Due to resonance, body parts vibrate at a greater magnitude than the applied force of vibration. Body muscles will react against this force by contracting in a voluntary or involuntary way. This causes body fatigue or reduced motor performance capacity. The lungs, abdomen and bladder are interfered with and may be irritated. Adverse effects are noted on the digestive system, genital or urinary and the female reproductive systems as well. In the mining industry, employees exposed to WBV reported frequent back pains. Vehicular jarring was reported amongst other symptoms like head and neck pains. With long term exposure to WBV, employees develop spinal column disease and complaints since the back is sensitive to vibration frequencies that range between 4-12 Hz. Digestive system diseases result from resonance movement of the stomach for frequencies ranging between 4 and 5 Hz. Frequencies below 20 Hz result in cardiovascular systems effects. These are hyperventilation, increased heart rate, oxygen intake, pulmonary ventilation and respiratory rate (Archer, n. d.). ii. Describe and critically evaluate the control measures used to manage exposure to vibration Critical analysis of measurement of actual vibration exposure Since vibration is defined by magnitude, signified by acceleration, expressed in m/s², and frequency, measured in hertz (Hz) or cycles per second, frequency weighting is used in calculating vibration exposure. Vibration evaluation takes three axes; vertical, fore and aft, and lateral axes for WBV. Frequency-weighted root-mean-square average is measured from the three axes. For WBV, acceleration values for X and Y (lateral axis) is multiplied by a factor value of 1.4, as 1.0 becomes the factor for vertical axis, Z. HAV has no multiplying factor. Vibration daily exposure A (8) for HAV is defined as the equivalent continuous acceleration, normalized to an eight-hour day; the A (8) value derived from the root-mean-square averaging of the acceleration signal and has units of m/s². A (8) is derived by the formulae: A (8) =ahv√T∕Tₒ where; T refers to the duration of exposure to vibration on a daily basis. The vibration magnitude is denoted by ahv and Tₒstands for eight hour duration. For WBV, equivalent continuous acceleration eight-hour period is the highest (rms) value, also called the highest vibration dose value (VDV) of frequency-weighted accelerations. The three orthogonal axes (1.4awx, 1.4awy, awz) are used for seated or standing worker. From the formulae, exposure action values are derived. The values are used by the employers to control vibration risks to their employees. Exposure limit values set protect the employees from harmful vibrations. Determining WBV exposure on employees is achievable through monitoring machines placed on vibrating machines. For example, a whole-body seat accelerometer is placed on a seat of a backhoe to determine vibration on an individual. Such gadgets can also be placed on vibrating hand machines to assist in establishing exposure to employees. A study conducted on operating engineers revealed that work-related musculoskeletal symptoms were common among operators of heavy machinery. These numbers varied, depending on the type of earthmovers the operators used: backhoe, crane, pushcat/dozer, pull scraper and front-end loader (Kittusamy & Buchholz, 2004, pp.256-260). Fig. 1 Fig. 2 Fig. 3 Discussion The charts above reveal results of musculo-skeletal symptoms of low back pains, neck pains, upper back pains and shoulders for operators exposed to WBV. Figure 1 records percentage of muculo-skeletal symptoms reported by plant operators. Low back pains were common among plant operators than knee and neck pains. The low back pains also forced most employees miss work to a greater degree than other pains (Fig. 2). The similar low back pains recorded the highest percentage for physician visits (Fig. 3). Plant operators expoed to WBV are at rik of experiencing low back pains than other musculo-skeletal symptoms. Vibration Control Measures Managing Vibration Risks Specific risk assessment is required in respect to vibration. The assessment must be recorded in writing and reviewed annually. Vibration control measures should be identified in the risk assessment to comply with the relevant legislative requirements. Investigation on daily exposure to vibration must be done. This assists in; Observing specific working practices; Referring to any relevant information on the levels of vibration in relation to the equipment used in the cited working conditions; Quantifying the magnitude of vibration employees are exposed to; and Considering other factors like manufacturer information about working conditions of the work equipment. Source of vibration (equipment and processes) Identification Equipment and processes that present potential exposure to vibration should be collectively identified by employees and trade union representatives. This is done through observation, availing data from the manufacturer of the machines and discussion. Any authoritative guidance from Health and Safety Advisers is of importance. Manufacturer’s data on vibration of machines should be treated with caution because vibration levels of machine change with time due to age and deterioration. The information obtained from the manufacturer must be compared with the level of exposure to the employees. This is determined through measurement of each tool or equipment. This helps in establishing exposure levels through calculations. From the calculations, the equipment is ranked in terms of risk against daily exposure. The daily exposure action value ranges between 2.5m/s² and 5.0m/s². Exposure Action Value 2.5m/s² Employees should be kept under health surveillance when exposed to vibration risks above the exposure action value. They must be provided with information, instruction and training like The technical measures adopted by the organization should comply with the relevant requirements; Exposure limit and action values; Important findings derived from risk assessment like measurements taken, accompanied with the findings. This should the answer the questions why, and how vibrations were detected, with a report on signs of injury; Right to appropriate health surveillance; Safety at workplace to minimize exposure to vibration. Exposure limit value 50m/s² This refers to the maximum value of vibration an employee should be exposed to on a daily basis. If the daily exposure exceeds this value, the employer should Ensure that the rate of exposure is reduced below this limit; Identify reasons related to the excess limit; and Monitor exposure limit frequently to avoid risks. Each tool should have its own derived trigger time. Traffic light marking or labeling system will assist employees identifies tools of greater exposure than others. For example, a red label for tools of highest risk, amber for medium risk and green for lower risk (Langer et al., 2012, pp. 304-311). Methods of Minimizing Risks Basic methods to apply are Substitution with non-hazardous processes like use of automated machines rather than powered hand tools; Modification of machines or process to reduce level of vibration; Modify vibration transmission path used by workers by use of anti-vibration handles, levers and automation; Forces needed to control the tools should be minimized; The trigger time should be reduced through job rotation and introduction of other tasks; During procurement of machines, priority should be given to machines of low vibration mode; Vibration machines should be mounted with anti-vibration during purchase and any other vibration control measures; The machines should be serviced regularly to keep vibration levels at the minimum. Maintenance schedule for the machines must be adhered to; Each equipment should be used for its designed purpose; Posture that result strains must be avoided. Information and Training The following information should be made available to employee and managers: The nature of risks of vibration; Symptoms and signs resulting from vibration; Reporting pattern for the symptoms to the line manager and occupational health adviser; Level of exposure to vibration on daily basis; The mode of health surveillance available. Bibliography Archer, W. (n. d.). Whole-body Vibration: Causes, effects and cures. Health and Safety. NAPIT. Available from: http://www.napitonline.com/downloads/CP%203%2007%20P%2022-23%20Health%20and%20Safety%20Vibration.pdf [Accessed 29/03/2013]. Kittusamy, K.N. & Buchholz, B. (2004). Whole-body vibration and postural stress among operators o construction equipment: A literature review. Journal of Safety Research 35. Elsevier Publishers; U.S.A. pp. 255-261. Langer, T. H. & etal. (2012). Reducing whole-body vibration exposure in backhoe loaders by education of operators. International Journal of Industrial Ergonomics 42. Elsevier Publishers. pp. 304-311. Read More