Measures Of Vibration Exposure Research Articles

Whole-body vibration exposure of heavy earthmoving machinery operators in surface coal mines: a comparative assessment of transport and non-transport earthmoving equipment operators

Purpose. Two groups of heavy earthmoving equipment operators, transport equipment (dumper) operators and non-transport equipment (drill and shovel) operators, in coal mines are assessed comparatively for their vibration magnitude and possible health consequences. Methods. Whole-body vibration exposure measurements were recorded according to Standard No. ISO 2631-1. Measurements were carried out at the operator–seat interface with a tri-axial seat pad accelerometer using a vibration analyser, followed by a questionnaire survey. The binary logistic regression model was used to comparatively assess the two groups of operators. Results. The binary logistic regression analysis revealed that the risk of lower back pain is 4.06 times greater (95% confidence interval [1.36, 12.08]) in transport equipment operators compared to non-transport operators. The daily vibration dose value of the transport equipment operators was 2.92 times greater than their counterparts (95% confidence interval [0.94, 9.09]). However, non-transport equipment operators belonging to the high driving experience category presented a value 5.26 times higher than the transport equipment operators. Conclusion. Transport equipment operators are more vulnerable to vibration hazards than their counterparts, as is evident from the vibration magnitude as well as from the symptoms of lower back pain.

A longitudinal study of neck and upper limb musculoskeletal disorders and alternative measures of vibration exposure

To investigate the exposure-response relationships between alternative frequency weightings of hand-transmitted vibration (HTV) and neck and upper limb musculoskeletal disorders (MSDs) in a cohort of HTV workers. In a three-year longitudinal study, the occurrence of neck and upper limb MSDs was investigated in 249 HTV workers and 138 control men. In the HTV workers, MSDs were related to measures of daily vibration exposure expressed in terms of 8-h energy-equivalent frequency-weighted acceleration magnitude [A(8)]. To calculate A(8), the acceleration magnitudes of vibration were weighted by means of four alternative frequency weightings of HTV. The associations between MSDs, individual characteristics, physical work load other than vibration, and psychological strain were also investigated. The occurrence of upper limb MSDs was greater in the HTV workers than in the controls. After adjustment for potential confounders, the occurrence of elbow/forearm and wrist/hand MSDs increased with the increase in vibration exposure. A measure of model selection did not reveal any substantial difference in the performance of the alternative frequency weightings of HTV for the prediction of neck and upper limb MSDs. In the study population, age, hard physical work load, and poor psychological well-being were associated with both neck and upper limb MSDs. In this study, there was evidence for significant exposure-response relationships between HTV exposure and MSDs in the distal sites of the upper limbs. There were no differences in the prediction of neck and upper limb MSDs between measures of daily vibration exposure calculated with alternative frequency weightings of acceleration magnitude.

A cross-sectional survey of hand arm vibration symptoms among angle grinder operators employed in sheet metal work in North India

This study investigates the prevalence of hand arm vibration symptoms and musculoskeletal disorders in the hand and arm of the angle grinder operators of sheet metal industries located in Chandigarh and nearby industrial areas in Northern India. Hand-transmitted vibration was measured in 42 sheet metal industries. A total of 83 workers, who were mainly employed for grinding job, were interviewed and vibration characteristics were measured using tri-axial accelerometer. Hand arm vibration symptoms, musculoskeletal complaints in hands and its correlation with tool weight were investigated. Results shown 84% daily vibration exposure measurements exceeded exposure action value (EAV) and 24% measurements exceeded exposure limit value (ELV). Hand arm vibration symptoms were finger numbness (40%), tingling (29%) and vibration white finger (VWF) (13%). Hand arm vibration symptoms in the workers were not significantly associated with tool weight. However, tool weight was significantly associated with musculoskeletal complaints in wrist, forearm and elbow of the workers. Preventive measures to reduce musculoskeletal complaints are proposed.

Relationships of neurosensory disorders and reduced work ability to alternative frequency weightings of hand-transmitted vibration.

This cohort study aims to compare the performance of alternative frequency weightings of hand-transmitted vibration (HTV) for the assessment of the exposure-response relationships for neurosensory disorders and reduced work ability among HTV-exposed workers. In a 3-year follow up study, the occurrence of neurosensory symptoms and reduced work ability, and the response to quantitative sensory testing (grip force, manipulative dexterity, touch sensation) were investigated in 249 HTV-exposed workers and 138 healthy controls. Among the HTV-exposed workers, the sensory outcomes were related to measures of daily vibration exposure expressed in terms of 8-hour energy-equivalent frequency-weighted acceleration magnitude [A(8)]. To calculate A(8), the acceleration magnitudes of vibration were weighted by means of four alternative frequency weightings of HTV. The occurrence of neurosensory symptoms, reduced work ability, and abnormalities of sensory tests was greater among the HTV-exposed workers than the controls. Among the HTV-exposed workers, the deterioration of neurosensory outcomes and the reduction of work ability increased on par with the measures of vibration exposure. Exposure-response models revealed that the four alternative frequency weightings of HTV provided the same predictions for the probability of finger numbness among the exposed workers (observed 36% versus predicted 32%). The findings of this study revealed significant dose-response relationships between measures of vibration exposure, sensory disorders, and reduced work ability among the HTV-exposed workers. There were no differences in the prediction of finger numbness between measures of vibration exposure calculated with alternative frequency weightings of HTV.

Epidemiological Evidence for New Frequency Weightings of Hand-Transmitted Vibration

This paper provides an overview of the exposure-response relationship for the vascular component of the hand-arm vibration syndrome, called vibration-induced white finger (VWF). Over the past two decades, several epidemiological studies have shown a poor agreement between the risk for VWF observed in various occupational groups and that predicted by models included in annexes to International Standard ISO 5349 (ISO 5349:1986, ISO 5349-1:2001). Either overestimation or underestimation of the occurrence of VWF have been reported by investigators. It has been argued that the current ISO frequency-weighting curve for hand-transmitted vibration, which assumes that vibration-induced adverse health effects are inversely related to the frequency of vibration between 16 and 1250 Hz, may be unsuitable for the assessment of VWF. To investigate this issue, a prospective cohort study was carried out to explore the performance of four alternative frequency weightings for hand-transmitted vibration to predict the incidence of VWF in groups of forestry and stone workers. The findings of this study suggested that measures of vibration exposure which give relatively more weight to intermediate and high frequency vibration produced better predictions of the incidence of VWF than that obtained with the frequency weighting currently recommended in International Standard ISO 5349-1:2001.

Measures of vibration exposure for a high-speed craft crew

The paper compares measurement-based measures for human vibration exposure. Data were collected during sea trials on a 10 m, 50 kn coastguard craft equipped with a three-axial accelerometer at the coxswain seat and with vertically mounted gauges measuring the acceleration of the cockpit floor. The ISO 2631-1:1997 measures of vibration (namely the root-mean-square (r.m.s.) value of the whole-body vibration (determined from the frequency-weighted acceleration signal), the maximum transient vibration value (MTVV), and the vibration dose value), the ISO 2631-5:2004 measure (namely the daily equivalent static compression dose Sed), and also statistically based measures to evaluate the acceleration magnitude are compared and discussed with respect to their ability to identify the mitigating effect of the suspension seat and how the different measures rank the severity of the high-speed craft (HSC) ride. The paper concludes that the r.m.s. value and the MTVV are unsuitable for evaluation of the conditions aboard while the other investigated measures show potential in this respect. Further the approach of ISO 2631-5:2004 taking both the short-term and the long-term perspectives on the human exposure to vibration is concluded to be the most mature method well suited to evaluation of HSC conditions.

Frequency weightings of hand-transmitted vibration for predicting vibration-induced white finger

The aim of this study was to investigate the performance of four frequency weightings for hand-transmitted vibration to predict the incidence of vibration-induced white finger (VWF). In a longitudinal study of vibration-exposed forestry and stone workers (N=206), the incidence of VWF was related to measures of vibration exposure expressed in terms of 8-hour frequency-weighted energy-equivalent root-mean-square (rms) acceleration magnitude [A(8)] and years of follow-up. To calculate A(8), the rms acceleration magnitudes of vibration were weighted by means of four frequency weightings: (i) W(h) (the frequency weighting specified in ISO 5349-1:2001); (ii) W(h-bl) (the band-limiting component of W(h)); (iii) W(hf) (a frequency weighting based on finger vibration power absorption); and (iv) W(hT) (a frequency weighting based on a Japanese study of VWF prevalence). The relations of VWF to alternative measures of vibration exposure were assessed by the generalized estimating equations (GEE) method to account for the within-subject dependency of the observations over time. Data analysis with a GEE logistic model and a measure of statistical fit suggested that calculating A(8) by weighting the tool rms accelerations with W(h-bl)gave better predictions of the cumulative incidence of VWF than the other alternative measures of daily vibration exposure. Values of A(8) derived from the currently recommended ISO frequency weighting Wh produced poorer predictions of the incidence of VWF than those obtained with frequency weightings W(hf)or W(hT). This prospective cohort study suggests that measures of daily vibration exposure which give relatively more weight to intermediate and high frequency vibration are more appropriate for assessing the probability of VWF.

Evaluation of Hand-Arm and Whole-Body Vibrations in Construction and Property Management

To identify and measure the magnitude of hand-arm vibration (HAV) and whole-body vibration (WBV) sources (tools, vehicles etc.) in use within a previously unexamined sector: a construction and property management company. To evaluate the effect of factors such as age of tool, materials being worked on, number and location of tool handles, tool weight, and manufacturer brand on HAV magnitude and the effect of factors such as manufacturer machine brand, terrain, and work task on WBV magnitude. This study was carried out in a construction and property management company, employees (n = 469) working in the engineering services and maintenance departments who use vibrating equipment as part of their work were invited to participate. Two hundred and eighty-nine employees working as general operatives, excavator drivers, stone masons, carpenters, labourers, fitters, welders, and gardeners agreed to participate. A total of 20 types of hand tool (n = 264) and 11 types of vehicle (n = 158) in use within the company were selected for inclusion in the study. Five pieces of equipment had never previously been measured. Vibration measurements were carried out in accordance with ISO 5349-1 (Mechanical vibration-measurement and assessment of human exposure to hand transmitted vibration-Part 1: general guidance. 2001) (HAV) and ISO 2631-1 (Mechanical vibration and shock: evaluation of human exposure to WBV in the working environment. Part 1-general requirements. 1997) (WBV). Vibration measurements were made while workers were operating the equipment as part of their normal work activities. A wide range of vibration emission values were recorded for most tool types, e.g. orbital sanders (1.39-10.90 m s⁻²) and angle grinders (0.28-12.25 m s⁻²), and vehicle, e.g. forklifts (0.41-1.00 m s⁻²) and tractors (0.04-0.42 m s⁻²). Vibration magnitudes were largely consistent with those found in previous studies. The highest HAV magnitude was measured on a demolition hammer (13.3 m s⁻²) and the highest WBV magnitudes were measured on an excavator with a rock breaking attachment (5.81 m s⁻²). HAV magnitudes were found to be particularly strongly influenced by tool age, while WBV magnitudes varied with work activity and terrain. Within the construction and management company, few hand tools (3 of 20) exceeded the exposure action values (EAV) specified in the European Physical Agents (Vibration) Directive 2002/44/EC [On the minimum health and safety requirements regarding the exposure of works to the risks arising form physical agents (vibration)], when used for an 8-h period. HAV magnitudes were found to be very dependent on tool age, highlighting the importance of a tool maintenance programme incorporating tool work life prediction supported by regular vibration exposure measurements. Most of the vehicles (10 of 11) tested in this study exceeded the EAV specified for WBV, when operated for 8 h. WBV magnitudes were found to be dependent on the work task and thus, job rotation could be employed to control WBV exposures to acceptable levels.

Vibration and shock exposure of maintenance-of-way vehicles in the railroad industry

The aim of this study is to investigate and compare vibration and shock measurements of maintenance-of-way vehicles used in the railroad industry for track maintenance and construction. Following international standards (i.e., ISO 2631-1: 1997) and professional guidelines the frequency weighted root-mean-square (r.m.s.) acceleration for each measurement axis, the vector sum, the seat effective amplitude transmissibility (SEAT), the crest factor (CF), the maximum transient vibration value (MTVV), the vibration dose value (VDV), the ratio and the newly proposed shock risk estimation factor ‘ R’ for spinal injury according to ISO 2631-5:2004 were measured and calculated for seven different maintenance-of-way vehicles during revenue service. Furthermore, a proposed alternative spinal injury prediction method, the VibRisk model, which incorporates different typical driver postures and operator physical characteristics was included for comparison with the ISO 2631-5 risk prediction. The results of the vibration exposure measurements depended on vehicle type, track/surface conditions and seat properties, with the tamper and bulldozer showing the highest r.m.s. vibration values. The vector sum ( a v) results ranged from 0.37 to 0.99 (m/s 2). Five of seven track maintenance vehicles would exceed the current Whole-body Vibration ACGIH-TLV ® guideline for an 8 h exposure duration in the vertical axis recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). The measured CF, MTVV/ a w and VDV/( a w· T 1/4) ratios were at or above the critical ratios in the majority of measurements given by the ISO 2631-1 (1997) and American industry guidelines by the American Conference of Governmental Industrial Hygienists (ACGIH-TLV). Comparing both prediction models for vibration shock risk for parts of the lumbar spine, different risk predictions and inconsistencies were found. The VibRisk model generally suggests different and higher risk of vertebral endplate failure for individual lumbar levels, whereas the ISO 2631-5 model indicated generally lower risks and did not differentiate between different disk levels and driver posture. Epidemiological studies validating the different shock risk models are lacking. Work modifications and adequate suspension seats would be beneficial for prevention of harmful exposure to vibration and shocks.

A longitudinal study of peripheral sensory function in vibration-exposed workers

To investigate prospectively the relation between vibration-induced sensory dysfunction and measures of daily exposure to hand-transmitted vibration (HTV). Thermal perception thresholds for warmth and cold (TPT in °C) and vibrotactile perception thresholds (VPT in dB) at 31.5 and 125 Hz were measured at the fingertips of digit II (for the median nerve) and digit V (for the ulnar nerve) of both hands in 27 male controls and 29 naval engine workers exposed to HTV. In the HTV workers, peripheral sensory function was investigated over a follow-up period of 1-3 years. Vibration exposure was expressed in terms of equivalent frequency-weighted acceleration [A (h(eq,T)) in ms(-2) rms], duration of exposure (T in hours), and frequency-weighted acceleration normalised to a period of 8 h [A(8) in ms(-2) rms]. At baseline, the HTV workers showed significantly higher TPT for warmth and lower TPT for cold than the controls, while no differences in the VPTs at both frequencies were observed between the two groups. After adjustment for several confounders, data analysis with the generalised estimating equations method and a transition model showed that the changes over time in the TPTs of the HTV workers were significantly related to all measures of daily vibration exposure [A (h(eq,T)), T, A(8)]. No significant associations were observed for VPTs at either 31.5 or 125 Hz. The findings of this longitudinal study suggest a significant exposure-response relationship between thermal sensory impairment over time and measures of vibration exposure. The measurement of TPT may be a useful testing method to assess vibration-induced neuropathy at an early stage.

Metrics of whole-body vibration and exposure–response relationship for low back pain in professional drivers: a prospective cohort study

The objective of this study was to investigate the relation between alternative measures of exposure to whole-body vibration (WBV) and low back pain (LBP) in professional drivers. The incidence of 12-month LBP, high pain intensity (numerical rating scale score > 5), and disability in the lower back (Roland and Morris disability scale score >or=12) was investigated in a cohort of 537 drivers over a 2-year follow-up period. LBP outcomes, individual characteristics, and work-related risk factors were investigated by direct interview using a structured questionnaire. Daily vibration exposure was expressed in terms of either equivalent acceleration over an 8-h reference period [A(8), root-mean-square (r.m.s.) method] or vibration dose value [VDV, root-mean-quad (r.m.q.) method]. From the vibration magnitudes measured on vehicles and total exposure duration, seven alternative measures of cumulative vibration exposure were calculated for each driver, using expressions of the form Sigma a (i)(m)t(i), where a (i) is the frequency-weighted r.m.s. or r.m.q. acceleration magnitude on vehicle i(a(ws) or a (wq), respectively), t(i) is the lifetime exposure duration for vehicle i, and m = 0, 1, 2, or 4. In the drivers' cohort, the cumulative incidence of LBP outcomes were 36.3% for 12-month LBP, 24.6% for high pain intensity, and 19.2% for disability in the lower back. A transition model, which takes into account the temporal sequence of cause and effect and captures the longitudinal part of the relationship, showed that VDV performed better than A(8) for the prediction of LBP outcomes. After adjusting for potential confounders, test for trends suggested an increased risk for developing high pain intensity and disability over time (and, to a lesser extent, 12-month LBP) with the increases of cumulative vibration doses computed from lifetime exposure duration and r.m.q. vibration magnitude (i.e. Sigma[a (wqi)(m)t(i)]). Measures of exposure duration, either daily or lifetime, also provided good indications of risk for LBP outcomes over time. Physical work load, but not psychosocial environment, was significantly associated with the occurrence of LBP outcomes over time. Measures of vibration exposure derived from exposure duration (daily or lifetime) and r.m.q. acceleration magnitude (VDV, Sigma[a(wqi)(m)t(i)]) were better predictors of LBP outcomes over time than measures of vibration exposure including r.m.s. acceleration (A(8), summation operator[a(wsi)(m)t(i)]). Patterns of exposure-response relationship were more evident for the outcomes high pain intensity or disability in the lower back than for the binary response 12-month LBP.

Self-reported musculoskeletal problems amongst professional truck drivers

Occupational driving has often been associated with a high prevalence of back pain. The factors that contribute to cause the pain are diverse and might include prolonged sitting, poor postures, exposure to whole-body vibration and other non-driving factors such as heavy lifting, poor diet or other psychosocial factors. In Europe, truck drivers are likely to be considered an ‘at risk’ group according to the Physical Agents (Vibration) Directive and therefore risks will need to be reduced. This questionnaire-based study set out to examine the relationship between musculoskeletal problems and possible risk factors for HGV truck drivers to help prioritize action aimed at risk reduction. Truck drivers (n = 192) completed an occupational questionnaire with two measures of vibration exposure (weekly hours and distance driven). Items on manual handling, relevant ergonomics factors and musculoskeletal problems were also included. Reported exposures to vibration ranged from 12 to 85 h per week, with a mean of 43.8 h. Distances driven ranged from 256 to 6400 km (mean 2469 km). Most of the respondents (81%) reported some musculoskeletal pain during the previous 12 months and 60% reported low back pain. Contrary to expectations, vibration exposures were significantly lower among those who suffered musculoskeletal symptoms when distance was used as an exposure measure. Manual handling and subjective ratings of seat discomfort were associated with reported musculoskeletal problems.

An epidemiological study of low back pain in professional drivers

The prevalence of low back pain (LBP) was investigated in 598 Italian professional drivers exposed to whole-body vibration (WBV) and ergonomic risk factors (drivers of earth moving machines, fork-lift truck drivers, truck drivers, bus drivers). The control group consisted of a small sample of 30 fire inspectors not exposed to WBV. Personal, occupational and health histories were collected by means of a structured questionnaire. Vibration measurements were performed on representative samples of the machines and vehicles used by the driver groups. From the vibration magnitudes and exposure durations, alternative measures of vibration dose were estimated for each subject. Daily vibration exposure, expressed in terms of 8-h energy-equivalent frequency-weighted acceleration, A(8), averaged 0.28–0.61 (range 0.10–1.18) m s −2 rms in the driver groups. Duration of exposure to WBV ranged between 1 and 41 years. The 7-day and 12-month prevalence of LBP was greater in the driver groups than in the controls. In the professional drivers, the occurrence of 12-month LBP, high intensity of LBP (Von Korff pain scale score ⩾5), and LBP disability (Roland & Morris disability scale score ⩾12) significantly increased with increasing cumulative vibration exposure. Even though several alternative measures of vibration exposure were associated with LBP outcomes, nevertheless a more regular trend of association with LBP was found for vibration dose expressed as ∑ a vit i (m s −2 h), in which the frequency-weighted acceleration, a v , and lifetime exposure duration, t, were given equal weight. In multivariate data analysis, individual characteristics (e.g. age, body mass index) and a physical load index (derived from combining manual materials handling and awkward postures) were significantly associated with LBP outcomes, while psychosocial work factors (e.g. job decision, job support) showed a marginal relation to LBP. This study tends to confirm that professional driving in industry is associated with an increased risk of work-related LBP. Exposure to WBV and physical loading factors at work are important components of the multifactorial origin of LBP in professional drivers.