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More than ever, human factors engineers and ergonomists need to justify our practice’s value to management. How can we effectively communicate with management? How should we present a Return on Investment (ROI) that leadership will find useful that addresses company profits, cost savings, productivity, first time quality, and turnover? What else does management care about other than ROI? This second panel in a two panel series will specifically highlight case studies in which presenters give examples of situations in which ROI for ergonomics was investigated from a business value. The session will start with four case study lectures followed by a panel discussion led by the moderators. The audience will be encouraged to participate with their own questions and comments.

The objectives were to examine inter-observer reliability of job-level forceful exertion analyses and temporal agreement of detailed time study results. Three observers performed the analyses on 12 different jobs. Continuous duration, frequency and % time of lifting, pushing/pulling, power and pinch gripping exertions and estimated level of the exertions were obtained. Intraclass correlation coefficient and variance components were computed. Temporal agreement analyses of raw time study data were performed. The inter-observer reliability was good for most job-level exposure parameters (continuous duration, frequency and % time of forceful exertions), but only fair to moderate for the estimated level of forceful exertions. The finding that the between-observer variability was less than the between-exertion variability confirmed that the forceful exertion analysis method used in the present study can detect job exertion differences.Using three observers to perform detailed time studies on task activities and getting consensus of the majority can increase the between-observer agreement up to 97%. STATEMENT OF RELEVANCE: The results inform researchers that inter-observer reliability for job-level exposure measurement of forceful exertion analysis obtained from detailed time studies is generally good, but the observers' ability in the estimation of forceful exertion level can be poor. It also provides information on the temporal agreement of detailed forceful exertion analysis and guidelines on achieving better agreement for studies where accurate synchronisation of task activities and direct physiological/biomechanical measurements is crucial.

Objective: The aims of this research were (a) to study the interrater reliability of a posture observation method, (b) to test the impact of different posture categorization systems on interrater reliability, and (c) to provide guidelines for improving interrater reliability. Background: Estimation of posture through observation is challenging. Previous studies have shown varying degrees of validity and reliability, providing little information about conditions necessary to achieve acceptable reliability. Method: Seven raters estimated posture angles from video recordings. Different measures of interrater reliability, including percentage agreement, precision, expression as interrater standard deviation, and intraclass correlation coefficients (ICC), were computed. Results: Some posture parameters, such as the upper arm flexion and extension, had ICCs ≥ 0.50. Most posture parameters had a precision around the 10° range. The predefined categorization and 30° posture categorization strategies showed substantially better agreement among the raters than did the 10° strategy. Conclusions: Different interrater reliability measures described different aspects of agreement for the posture observation tool. The level of agreement differed substantially between the agreement measures used. Observation of large body parts generally resulted in better reliability. Wider width angle intervals resulted in better percentage agreement compared with narrower intervals. For most postures, 30°angle intervals are appropriate. Training aimed at using a properly designed data entry system, and clear posture definitions with relevant examples, including definitions of the neutral positions of the various body parts, will help improve interrater reliability. Application: The results provide ergonomics practitioners with information about the interrater reliability of a postural observation method and guidelines for improving interrater reliability for video-recorded field data.

Background Lateral epicondylitis is a common work-related musculoskeletal disorder. The objective of this study was to identify risk factors associated with lateral epicondylitis among active workers. Methods Seven-hundred thirty-three workers in 12 Washington worksites participated in structured interviews, physical examinations, and individual exposure assessments of biomechanical and psychosocial factors. Multivariable logistic modeling was used. Results Thirty-eight subjects (5.2%) had lateral epicondylitis. Age (36–50 years-old), being female, and low social support at work were significant risk factors. Frequency of forceful exertion (≥5 vs.

This paper addresses the issue of quantifying forceful exertions of lifting, pushing/pulling, pinch and power griping with several commonly used methods (direct measurement, force-matching, ergonomist estimation based on observation and worker's self-report). The aims were to study differences of ergonomists in making decisions of collecting forceful exertion data, ability of the studied force quantification methods in detecting exposure differences between jobs, and relationships between measurements obtained by different methods. Seven hundred and thirty-three (733) subjects participated in the study, and 2482 forceful exertions were quantified with the selected force quantification methods. Results showed that the determination of whether a forceful exertion was considered important enough to be measured was very subjective. More objective criteria need to be developed. Although the different force quantification methods could detect exertion-level differences between different types of jobs, the sensitivity of detecting the difference varied. Direct measurement of lifting and pushing/pulling forces seems to be slightly more sensitive than ergonomists’ estimates, and the force matching of grip forces may be more sensitive than workers’ self-reports. Ergonomists estimations through observation seem to be a good alternative for measuring forceful exertions. Pearson correlation coefficients between force estimations obtained by the different methods were between 0.28 and 0.71. The degrees of the correlations between the different measurement methods varied. This indicates that the different methods might quantify different aspects of the forceful exertions. These methods may not necessarily be used interchangeably in job evaluation tools. Different weights and/or cut-points may need to be developed when different force quantification methods are used. Relevance to industry Objective criteria of collecting forceful exertion data in job evaluations need to be developed. Different forceful exertion quantification methods may be used in job evaluations. However, different cut-points classifying jobs risk levels should be used when different exertion quantification methods are used.

Six different methods to calculate the Strain Index (SI) scores for jobs with multiple forces/tasks were developed. Exposure data of 733 subjects from 12 different worksites were used to calculate these SI scores. Results show that using different SI computation methods could result in different SI scores, hence different risk level classifications. However, some simpler methods generated SI scores were comparable to the more complicated composite SI method. Despite differences in the scores between the six different SI computation methods, Spearman rank-order correlation coefficients of 0.61-0.97 were found between the methods. With some confidence, ergonomic practitioners may use simpler methods, depending on their specificity requirement in job evaluations and available resources. Some SI computation methods may tend to over-estimate job risk levels, while others may tend to under-estimate job risk levels, due to different ways used in obtaining the various SI parameters and computations.

Aim This paper examines the reliability of an observational tool used to assess the organization of work. Scope The utility of the tool was assessed through inter-item correlations (Spearman coefficients), inter- and intra-rater reliability (kappa statistics), factor analysis (principal components) and internal consistency reliability (Cronbach's alpha). Conclusions Results from the study indicated one global underlying dimension measured by the tool items. Inter- and intra-reliability was good to substantial among tool items. Results indicate this tool has good utility in assessing work organization. Relevance to industry Research investigating the individual effects of work organization and its combined effects with physical workload has become an area of inquiry.

This study evaluated two subjective assessment methods for physical work-related musculoskeletal disorder (WMSD) risk factors. A total of 567 participants from 12 companies in the manufacturing and health care industries were evaluated using the hand activity level (HAL) threshold limit value (TLV) and the Strain Index. Inter-rater reliability comparisons were performed on 125 selected cyclic tasks, with one novice and three experienced raters. Predictive validity was assessed by evaluation of relationships between measured exposure parameters and diagnosed WMSDs of the hand/wrist and elbow. HAL hand repetition ratings had a Spearman r value of 0.65 and a kappa value of 0.44 between raters. Subjective force (0-10 scale) estimates had a Spearman r = 0.28 and were not significantly different between raters (p.05). The rating comparison for the four subjective components of the Strain Index had Spearman r correlations of 0.37-0.62 and kappa values of 0.25-0.44. The Strain Index and HAL TLV agreed on exposure categorization 56% of the time. Logistic regression showed, after adjustment for age, gender, and body mass index, that higher peak hand force estimates (odds ratio [OR] 1.14, confidence interval (CI) 1.02-1.27), most common force estimates (OR 1.14, CI 1.02-1.28), hand/wrist posture rating (OR 1.71, CI 1.15-2.56), and Strain Index scores/= 7 (OR 1.82, CI 1.04-3.18) were associated with distal upper extremity disorders in the dominant hand. HAL repetition ratings/= 4 (OR 2.81, CI 1.40-5.62) and hand/wrist posture ratings (OR 1.59, CI 1.01-2.49) were associated with disorders in the nondominant hand. These findings show moderate to good inter-rater agreement and significant relationships to health outcomes for the identified measures.

Problem Cost-benefit analysis (CBA) can help to justify an investment in ergonomics interventions. A predictive CBA model would allow practitioners to present a cost justification to management during the planning stages, but such a model requires reliable estimates of the benefits of ergonomics interventions. Method Through literature reviews and Internet searches, 250 case studies that reported the benefits of ergonomics programs and control measures were collected and summarized. Results Commonly reported benefits included reductions in the number of work-related musculoskeletal disorders (WMSDs) or their incidence rate, as well as related lost workdays, restricted workdays, and workers' compensation costs. Additional benefits reported were related to productivity, quality, turnover and absenteeism. Discussion Benefits reported were largely positive, and payback periods for ergonomics interventions were typically less than one year. Summary The results of this review could be used to develop predictive CBA models for ergonomics programs and individual control measures. Impact on Industry Cost-justifying ergonomics interventions prior to implementation may help to secure management support for proposed changes. Numbers used for the benefits side of a cost-benefit analysis (CBA) need to be based on “real world” data in order to be credible. The data presented in this paper may help in the development of simple cost-benefit models for ergonomics programs and control measures.

PROBLEM: The trucking industry experiences one of the highest work-related injury rates. Little work has been conducted previously in the United States to assess the hazards, needs, and injury prevention priorities in trucking. Method: Two separate industry-wide surveys of 359 trucking companies and 397 commercial truck drivers were conducted in Washington State. Results: Trucking companies and drivers both ranked musculoskeletal and slip, trip, fall injuries as the top two priorities. Controlling heavy lifting, using appropriate equipment, and addressing slippery surfaces were frequently listed as solutions. There appears to be a gap in safety climate perception between workers and employers. However, driver and company priorities agreed with industry workers' compensation claims. There is room for safety program management improvement in the industry. The study findings detail opportunities for prioritizing and reducing injuries. Impact on Industry: This information can be used to focus and design interventions for the prevention of work-related injuries while improving industry competitiveness. Language: en

A novel express checkstand with basket cut-out was developed and evaluated in a small grocery store chain. Eight checkers performed three trials of simulated grocery checkout work with actor customers using both old and new checkstand designs. Usability was assessed by survey, structured interview and observation. Time-motion video analysis was used to evaluate differences in body postures, motions, and productivity. The new express checkstand design, which lowered and angled the presentation of the grocery basket, significantly (p

This paper presents two posture risk quantification methods: first, an event-based method where the most common and the worst postures are estimated in a task; second, a time-based method where posture distributions are calculated from random samples of observed postures in the task. A 'click-on-screen' posture data entry method was developed for the time-based posture analysis method to make the observation process easier and to reduce possible posture categorization bias. Both methods were used to quantify various work posture parameters among a study cohort of 733 subjects from a prospective epidemiological study of upper extremity musculoskeletal disorders. Composite posture indices using a modified Rapid Upper Limb Assessment (RULA) method were also computed using data obtained by the two posture analysis methods. Results showed that both methods were able to distinguish jobs with large differences in certain posture measures. However, they did not produce the same results and could not be used interchangeably. Risk evaluation criteria should be developed, either for specific posture parameters or as a composite index, with a well-defined postural analysis method, so that users can follow exact procedures and obtain comparable results. The event-based method is easy to use and may suit practitioners better, while the time-based method adds more information to the measurement and may suit users who want more detailed information about posture exposure.

Many modern tower silos used in the agricultural industry for hay and grain storage are oxygen-limiting by design. Forced-air ventilation using a forage blower is a method commonly used to decrease concentrations of toxic and asphyxiant gases and to increase the O2 content within a silo headspace prior to worker entry. This article describes the methods used to measure gas concentrations and the results obtained from a pilot study by the Washington Fatality Assessment and Control Evaluation (FACE) program of two oxygen-limiting forage tower silos in eastern Washington State. The silos were monitored for oxygen (O2), nitrogen dioxide (NO2), and carbon dioxide (CO2). Measured O2 concentrations were low in all areas of the headspaces monitored for both silos. After beginning forced-air ventilation, O2 concentrations within the silo headspace returned to ambient levels within 8 to 20 min. Nitrogen dioxide levels exceeded the Washington Industrial Safety and Health Act (WISHA) short-term exposure limit (STEL) in the silo that was filled six days earlier (silo 2), but not in the silo that was filled four days earlier (silo 1). The NO2 concentration in silo 2 decreased to below the WISHA STEL within 15 min of starting ventilation but began to rise shortly after ventilation was stopped. Carbon dioxide, which was only measured in silo 1, was detected at 2% within the headspace of this silo. The carbon dioxide concentration decreased to

Adoption of the Washington State Ergonomics Rule in 2000 initiated seven different demonstration projects in nine high-risk construction trades. The Ergonomics Rule was repealed in 2003, however valuable cooperative field research was conducted in construction prior to rule dissolution. This paper presents summaries and results of each project with the aim of providing the results to construction professionals and researchers seeking to identify and reduce injury risks and building costs. The projects were organized independently but each with the specific aims of conducting work in conjunction with industry, identifying “hazard zone” risk factors as defined by the rule, and identifying feasible solutions in agreement with company partners to mitigate these risk factors. Musculoskeletal injury risk factors were evaluated by ergonomist field observation and working group analysis. Solutions were developed through field work and consensus agreement with industry and labor representatives. Identified injury ...

A study was conducted to assess the efficacy of calibrating subjective worker ratings of hand exertions to reduce error in estimates of applied force. Twenty volunteer subjects applied pinch and power grip forces corresponding to their perceptions of different Borg CR-10 scale levels using both "grip-to-scale" and "guided-grip" procedures. These data were used separately to define relationships between scale ratings and actual force application. Two gripping tasks were performed and corresponding subjective hand force ratings were calibrated using the grip-to-scale calibration data. Results showed that the mean estimation error for a 44.5 N (10 lb) power grip task was significantly reduced from 142.8 (+/-69.0) to 62.3 (+/-58.3) N. The guided-grip calibration method also significantly reduced rating error for the power grip task, however the estimates were biased toward zero. Neither calibration procedure improved rating accuracy of an 8.9 N (2 lb) pinch grip task. The study results indicate that calibration of hand force ratings using the grip-to-scale procedure may improve the accuracy of hand exertion measurements using the Borg CR-10 scale.

In primary prevention efforts to reduce the incidence of work-related musculoskeletal disease (MSD), many employers will use supervisor or worker assessments for initial evaluation of MSD risk factors. This cross-sectional study examined the ability of supervisors and workers to accurately assess the presence of MSD risk factors at four work sites in four different industries, examining five jobs that represented six primary categories of risk factors: posture, force, repetition, impact, lifting, and vibration. Thirty-seven supervisors and 55 workers assessed the jobs they oversee or perform through the use of a 14-item questionnaire. Their assessments were compared with detailed ergonomist job analyses to determine their accuracy in identifying the presence or absence of MSD risk factors. In assessing the absence or presence of all risk factors, agreement with the ergonomist was found 81% of the time for supervisors and 77% of the time for workers. Overall, supervisors and workers overestimated the presence of risk in assessing the jobs. Supervisors and worker assessments appear promising in recognizing risk in initial ergonomic assessments.

This prospective study is following a cohort of up to 1000 workers for three years to determine the relationship between risk factors and confounders and the development of clinically diagnosed upper extremity musculoskeletal disorders (UEMSDs). Results from 535 workers at baseline in manufacturing and service industries showed that 28.8% of jobs had an average RULA grand score of 5–7 for the right side of the body, and 24.1% for the left. The average and median Strain Index scores for the right side were 19.8 (±42.5) and 5.1, and for the left side were 16.4 (±41.0) and 3.4. HAL TLV analysis showed that 65.7% of subjects were below the Action Limit for the right side and 71.6% for the left, while 18.7% were over the TLV for the right side and 15.2% for the left. These data in combination with more detailed measurements will be used in prospective analysis to quantify the relationship between risk factors and UEMSD outcomes.

An engineering solution to remove an injury risk factor is the preferred route for preventing musculoskeletal injuries when feasible. Construction has presented a challenge that is only recently being aided by new tool designs and work in the area. However, many risks are introduced or exacerbated by factors “out of their control”. Several projects in Washington State have investigated the benefits of working with manufacturers and architects to reduce the level of risk before the construction phase by repackaging materials or considering alternative designs with worker health and safety taken into account. To reduce lifting risks, composition shingles were successfully repackaged in lighter bundles weighing 48–50 lbs (previously 64 lbs) in cooperation with a large manufacturer. This intervention is presented as an example of working upstream to reduce injury risks.

This paper describes a battery of physical exposure assessment methods used in a large prospective upper extremity musculoskeletal disorders study. Different from some previous prospective studies, this study collects health and physical exposure data for each study subject rather than at a group level. Subjects are recruited from different job categories based on their hand activity exposure categories. Multiple exposure assessment methods are used to measure job physical exposures such as force, repetition, and work posture. This will allow us to compare the sensitivity of different exposure assessment methods in predicting the risk for upper extremity musculoskeletal disorders. Procedures have also been taken to monitor inter-observer reliability for some observational analyses. During the first year of the study, baseline exposure measurements have been collected from 607 volunteers at 11 different worksites. Follow-up measurements have also been collected in these worksites. Whenever a participant has a significant job change, a new exposure assessment is conducted at the new job. This paper will primarily discuss the various exposure assessment methods used in this study, and use some preliminary results to demonstrate some of the data reduction methods.

Washington State Department of Labor and Industries enacted an Ergonomics Rule in May, 2000. The rule requires that companies evaluate “caution zone” jobs and reduce specific risk factor levels found to be above a “hazard” level. At least half of the highest risk industries for musculoskeletal injuries are in construction. This has led to the development of cooperative ergonomics projects with roofing, drywalling, mason, mechanical and general contractors. The results of these projects provide a foundation describing what compliance with the Washington rule will look like in these industries. Construction environments present many challenges but this work has demonstrated that feasible and low-cost solutions are available to reduce risk factors below the regulatory level requiring intervention. Examples of “hazard-level tasks” and risk factor reduction in roofing, mechanical contracting and drywalling are presented.

One of the major ergonomics activities in SHARP is to identify risk factors which may cause work-related musculoskeletal disorders in workplaces and recommend effective solutions to help industries to improve their work conditions. Effective identification of risk factors and provision of specific solutions require a sensitive, valid and reliable measurement system. A continuous effort in SHARP has been to develop such a system to fulfill our goals. This paper discusses some major elements in the system, i.e. measurement of physical exposures of the operators, quantification and documentation of task distribution of jobs, and establishment of relationships between physical exposure measurement and task operations. Three field applications (wood processing, poultry processing and data entry jobs) of this measurement system are presented in this paper.

A pilot study was conducted as part of a larger project to assist a labor/management ergonomics team at a bareroot tree nursery in Washington State in developing potential solutions for reducing or eliminating risk factors for work-related musculoskeletal disorders (WMSDs). Measurements were collected of employees performing the jobs of Bin Unloading, Grading/Counting and Bag Closing using two different work techniques and workstation settings. Muscle activity (electromyography) of the distal upper extremity and back motion (Lumbar Motion Monitor) on three axes were recorded to determine differences in the WMSD risk factors between techniques. Bin unloading was performed with a bin flat on the stand and with the bin raised and tilted towards the worker. For grading/counting, the conveyor belts used to move trees were arranged in a stacked configuration and a side-by-side configuration. Closing the bags was performed by rolling the bag with two people and by folding the bags with one person. Paired t-tests were used to compare EMG data between methods and a mixed model was used to analyze LMM data. In general, grading/counting trees from a side-by-side conveyor configuration appeared to have slightly higher levels of finger flexor muscle activity, higher deltoid EMG static levels and back velocity and acceleration than grading from an over-under configuration. However, the differences were significant only for acceleration on the side bending and rotational axis and velocity on the sagittal and rotational axis. Workers unloading seedlings from bins that were raised and tilted forward experienced higher static, median and peak muscle levels, but slightly lower back velocity and acceleration. However, these results were not statistically significant. Bag folding appeared to have significantly higher levels of musculoskeletal risk factors, including higher deltoid, flexor and extensor muscle activity and higher ranges of movement, velocities and accelerations of the back. However, the number of workers exposed is less than for bag rolling.

Electrogoniometers currently represent the most feasible way of obtaining direct measurements of wrist and forearm posture and motion in varied work environments. Researchers have shown that a significant amount of error may be present in the recordings from these instruments (Buchholz and Wellman, 1997; Armstrong et al., 1993). This study showed that even with “state of the art” correction methods, wrist flexion/extension and wrist deviation duration measurements may still vary by as much as 100% plus or minus the measured result in the 95% confidence interval. Forearm extreme posture duration intervals were equal to or less than 40% of the calculated values. Wrist flexion/extension and forearm rotation repetition measurements were more accurate, giving confidence intervals plus or minus less than 25% of the resulting values. Wrist deviation repetition confidence intervals were wider, at plus or minus 100% or greater and generally including zero. These results highlight the need to address accuracy when reporting measurements of the upper extremities and to promote further research into the development of accurate measurement methods.

This study quantitatively investigated the physical exposure in the upper extremities of poultry processing operators, by electromyography (EMG) and psychophysical methods. Results showed that all three poultry processing jobs had high loads on the forearm flexor and extensor muscles. Loading on the shoulder region may not be a major concern for many of the operators. However, some individual operators may still be exposed to high shoulder loads possibly due to the mismatch between the workstations and the individual operators.

Regional discomfort questionnaires were administered to apprentice carpenters at three month intervals for a duration of six months following an ergonomics awareness training as part of apprenticeship school. Reports of frequent musculoskeletal discomfort were reported by between 20 and 29 percent of carpenters for each of the nine body regions with the exception of higher levels for the lower back. Severity ratings and frequency of discomfort were highest for the lower back and hands/wrists. There was no significant difference in reports of musculoskeletal discomfort among the baseline and follow-up questionniares (p > 0.05). The lower back was the only body region showing a decrease in the ratings of discomfort severity during follow-up. Further study of training effects on work methods and discomfort are recommended.

This study aimed to introduce a method of simultaneous combination analysis of multiple exposure parameters for large epidemiological studies of work-related upper-extremity musculoskeletal disorders (MSD) and compare this analysis method with the conventionally used job-level combination analysis method when applied in exposure-response analysis of work-related upper-extremity MSD.Health outcome [carpal tunnel syndrome (CTS)] and physical exposure (forceful exertion and hand/wrist postures) data for 733 subjects were obtained from the baseline period of a 3-year work-related upper-extremity MSD study. Determinations of CTS cases were done based on a set of defined criteria. Physical exposure variables of several different types of forceful exertions and three different hand/wrist postures were collected onsite, processed, and analyzed using both a simultaneous combination and job-level combination analysis method.The commonly used job-level combination analysis method resulted in significantly different combination exposure distributions compared to the simultaneous combination analysis method, although the absolute differences were small. Both methods showed some significantly higher combined force-posture exposures among CTS cases than non-cases.The simultaneous combination method provides more realistic distribution information on combined exposure parameters compared to the job-level combination method that has been commonly used in epidemiological studies. The newly developed simultaneous combination analysis method needs to be used in larger scale work-related upper-extremity MSD epidemiological studies to test its predictive power compared to the job-level combination analysis method.

Objectives The aim was to explore whether ”adjustment” for gender masks important exposure differences between men and women in a study of rotator cuff syndrome (RCS) and carpal tunnel syndrome (CTS) and work exposures. Methods This cross-sectional study of 733 subjects in 12 healthcare and manufacturing workplaces used detailed individual health and work exposure assessment methods. Multiple logistic regression analysis was used to compare gender stratified and adjusted models. Results Prevalence of RCS and CTS among women was 7.1% and 11.3% respectively, and among men 7.8% and 6.4%. In adjusted (gender, age, body mass index) multivariate analyses of RCS and CTS, gender was not statistically significantly different. For RCS, upper arm flexion ≥45° and forceful pinch increased the odds ratio (OR) in the gender-adjusted model (OR 2.66, 95% CI 1.26-5.59) but primarily among women in the stratified analysis (OR 6.68, 95% CI 1.81-24.66 versus OR 1.45, 95% CI 0.53-4.00). For CTS, wrist radial/ulnar deviation ≥4% time and lifting ≥4.5 kg ＞3% time, the adjusted OR was higher for women (OR 4.85, 95% CI 2.12-11.11) and in the gender stratified analyses, the odds were increased for both genders (female OR 5.18, 95% CI 1.70-15.81 and male OR 3.63, 95% CI 1.08-12.18). Conclusions Gender differences in response to physical work exposures may reflect gender segregation in work and potential differences in pinch and lifting capacity. Reduction in these exposures may reduce prevalence of upper extremity disorders for all workers.

Legislation and product development in the USA has prompted an interest in mirror-use by traffic flaggers to improve awareness of vehicles approaching from behind. Helmet- and flagpole-mounted configurations were studied using a graphical approach with field verification studies by comparing fields of view, object magnifications, and human factors considerations. Plane and convex mirrors with different radii of curvature were investigated. Results found image formation on helmet-mounted convex mirrors occurs too close to the mirror. A 0.038 m helmet-mounted plane mirror performed similarly to a 0.076 m diameter, 0.508 m radius of curvature convex mirror. Fields of view and image information between helmet-mounted plane mirrors and flagpole-mounted convex mirrors were compared. Issues of image perception, practical use, and attention were identified; they pose serious issues for use as a primary safety device. Additional investigation is needed to determine the requirements and applicability of mirror-use for flagging in work zones.

A continuous scale observational method was used as part of a methods comparison study to estimate force and velocity for the upper extremities. Scales developed by Latko (1997) were used to collect 11,000 samples of physical factors from videotape. Eighteen workers were observed performing three different tasks. A small inter/intra-observer comparison was done to evaluate the precision and repeatability of the method. Results appear to indicate that observers may show better agreement when estimating more forceful exertions. Wrist velocity estimations showed less variation than forearm rotation, which may indicate that observers have more difficulty estimating velocity of body segments rotating on the longitudinal axis. Further research in this area is needed to ascertain whether observational methods can discriminate between levels of force and velocity measures.

To identify factors associated with rotator cuff syndrome (RCS) among active workers.Seven hundred thirty-three workers in 12 worksites participated in a cross-sectional study with individual structured physical and psychosocial health interviews, physical examinations, and exposure assessments of biomechanical factors. Work organization, including job content or structural constraints, was assessed at the departmental level. Multivariable logistic modeling was used.Fifty-five subjects (7.5%) had RCS. Cases were more likely to report low job security (P0.04) and to have very high job structural constraints (P0.03). Age and body mass index were marginally significant. Upper arm flexionor= 45 degreesor= 15% of time and either duty cycle of forceful exertionsor=9% time (odds ratio = 2.43, 95% CI = 1.04 to 5.68) or forceful pinch0% [odds ratio = 2.66, 95% CI = 1.26 to 5.59] were significant risk factors.Long duration of shoulder flexion and forceful exertion (especially pinch) in a job are significant risk factors for RCS. Work organization may impact physical and psychosocial exposures and should be further explored.

A survey of farms in Washington State was conducted to determine tractor characteristics and the presence of rollover protective structures (ROPS) in a state with more inclusive rules on tractor retrofitting than federal regulations. A total of 544 valid surveys were completed from a proportional random sample across different types of farms. Responders indicated that 58% of tractors overall were equipped with ROPS, and 42% of the tractors without ROPS were exempt from the state rules. Seatbelts on tractors equipped with ROPS were reportedly used “sometimes” or more 30% of the time, and 17% of these tractors had no seatbelt installed. Tractors used for row crop farming were significantly more likely to be equipped with ROPS than those used for tree, vine, or hops farming. Older tractors were used for fewer hours, were less likely to be ROPS-equipped, and were less likely to be operated while wearing a seatbelt. The results were consistent with a positive effect of the Washington State ROPS requirements, demonstrated by the increased percentage of ROPS-equipped pre-1976 tractors, as compared to other states, and by the difference between ROPS-equipped tractors in exempt and non-exempt types of farming. The results point to the need for prevention activities to increase seatbelt use on ROPS-equipped tractors, and for further development of practical protection for tractors operating under overhead obstacles.

An exposure measurement approach is described for quantifying repetitive hand activity of individual workers in a prospective epidemiological study on work-related upper extremity musculoskeletal disorders. A total of 733 subjects were involved in this study at the baseline. Hand activities were quantified by force and repetition. Force levels were measured by workers' self-reports, ergonomists' estimates based on observation and measurements with instrumentation. Repetition levels were measured by detailed time-motion analyses using two repetitive hand activity definitions and ergonomists' estimates using scales for the American Conference of Governmental Industrial Hygienists hand activity level and the Strain Index. Results showed that the present exposure assessment approach seems to be able to quantify force level and repetitiveness of hand activities. Repetitive hand activity is quantified differently depending on whether forceful hand exertion or repetitive muscle activity is used as the definition. These hand activity definitions may quantify different physical exposure phenomena. Individual exposure assessment is important in epidemiological research of musculoskeletal disorders as there are interactions between the individual subjects and the measured parameters. These interactions may vary between exposure parameters.

This paper focuses on comparisons between the different methods of assessing repetitive hand activities. Various methods were used to measure hand force and repetitiveness of hand activities on 733 subjects in the study described by Bao et al. (2006). Two definitions of repetitiveness were used in analysis of detailed time studies of repetitive hand activities and four parameters of the American Conference of Governmental Industrial Hygienists (ACGIH) hand activity level (HAL) and the Strain Index methods were estimated by ergonomists and used to quantify repetitiveness. Hand forces were measured or estimated using three different methods: 1) measured with a force gauge or mimicked on a force gauge (force matching); 2) estimated by ergonomists using rating scales; 3) self-reports by subjects. The jobs were also evaluated using the ACGIH HAL and Strain Index methods when different repetitiveness quantification methods were used. Results showed that different definitions of repetitive exertion might lead to measuring different physical exposure phenomena and produce very different results. There were poor correlations between the measures of repetitiveness estimated by the different methods. Correlations between force quantifications using different methods were also poor. This suggests that parameters measured by different methods might not be interchangeable. Both the ACGIH HAL and Strain Index methods identified more 'hazardous' jobs when repetitiveness was estimated by ergonomists than when it was calculated by detailed time studies of forceful hand exertions. The Strain Index method identified more 'hazardous' jobs than the ACGIH HAL method. Overall, the between-methods agreements were found to be moderate to substantial.

Introduction In Washington State, 87 workers are killed each year, on average, while in work status. To understand these incidents and to assist in focusing on and development of potential prevention measures, they must be well characterized. Methods Work-related fatalities between the years 1998 and 2002 are described by the demographics of the victims, types of incidents, the victims' occupations, and industries and location in which they worked. Results Motor vehicle- and machinery-related incidents accounted for nearly 33% and 14% of the incidents, respectively. Agriculture, forestry, fishing, hunting, and mining (n = 87), and construction (n = 83) had the most fatalities. Fatality rates per 100,000 workers for these industries were 25.7 and 8.7, respectively, compared to the state-wide average of 3.1 fatalities/100,000 workers. Discussion These data indicate numerous areas for prevention of work-related traumatic injuries and fatalities.

A cross-sectional study of jobs at four bareroot reforestation tree nurseries in Washington and Oregon investigated the prevalence of musculoskeletal symptoms and potential work-related musculoskeletal disorders (WMSDs), and analyzed their association with physical and psychosocial risk factors of the jobs. Questionnaires were used to assess symptoms and psychosocial factors. Direct observational work sampling was utilized to estimate physical risk factors. The response rate for the questionnaires was 41% (203 subjects), of which 72% reported recurring symptoms in the past year. The most common body region was the wrist/hand (42%). Pain was the most commonly reported symptom. Forty-one percent of the subjects had at least one potential WMSD, the hand region having the greatest number of cases (n = 51). The average age of those with and without potential WMSDs did not significantly differ; however, tenure at the nursery (p0.03) did. Being female (OR = 7.37; 95% CI = 2.75, 19.7,) high job satisfaction (OR = 0.32; 95% CI = 0.15, 0.72), and having a second job (OR = 3.76; 95% CI = 1.12, 12.57) were significantly associated with potential WMSDs. No significant difference in WMSD prevalence was found between the field and packing shed areas of the nurseries (p = 0.88). Pinch gripping was observed 24% of the time in the shed and 8% of the time in the field. Torso flexion was observed more often in the field than the shed (38% vs. 18% of the time). This study found that both physical and psychosocial factors associated with WMSDs are present in bareroot trees nurseries.

Tool and equipment purchasing decisions are constantly made by companies and workers, often with little objective information beyond word of mouth and marketing information. This study presents a pilot investigation of random orbital sanders using ergonomic and usability assessment techniques which can easily be applied in any industry. Three subjects performed a sanding task using three different tool configurations: 1) the current model sander, 2) current model with hose-swivel attachment, and 3) the new "ergonomically designed" model. Physical measurements were taken of muscle activity and wrist motion to complement think-aloud testing and a usability questionnaire. No significant differences were found in physical measurements between the three configurations. Participants strongly preferred the current model over the new model, reporting less perceived discomfort and vibration, despite what appeared to be improvements in the new design. Workplace changes intended to reduce the risk of injury sometimes may have no effect after significant capital investment, or in some cases even increase the risk of injury. Practical assessment of new tools or modifications can quickly determine whether the outcome is indeed an improvement. The results of this tool assessment highlight the need for objective information in tool and equipment design decisions.

The prevention of work-related musculoskeletal disorders has become a national priority in many countries. Increasingly, attempts are made to quantify those exposures that increase risk in order to set exposure limit values. This study used commonly employed field measurement methods and tools in order to perform an inter-method comparison between three primary methods of risk factor exposure assessment: self-report questionnaires, observational video analysis and direct measurement. Extreme posture duration, repetition, hand force (estimated from electromyography) and movement velocity were assessed for 18 subjects while performing each of three jobs processing tree seedlings. Results indicated that self-reports were the least precise assessment method, which consistently overestimated exposures for each of the measured risk factors. However, adjustment of the reports as psychophysical scales may increase agreement on a group level. Wrist flexion/extension duration and repetition were best measured by electrogoniometer. Electrogoniometric measures of wrist deviation duration and frequency were less precise than video analysis. Forearm rotation duration and repetition, grip force and velocity appeared to be best quantified by direct measurement as measured by electrogoniometer and electromyography (EMG) (as root-mean-square amplitude). The results highlight the fact that it is as important to consider and report estimated measurement error in order to reduce potential exposure misclassification in epidemiologic studies.

A self-report questionnaire was developed to evaluate the potential for assessment of possible risk factors for musculoskeletal disorders. Visual-analog and categorical scales were designed to represent responses relating to primary work as well as a second job and hobbies or non-work activities. 71 tree nursery workers completed the scales twice in consecutive weeks. Agreement between means of the two questionnaire administrations was 0.80 or higher for all scales. Intraclass correlation coefficients ranged between 0.59 and 0.69 for the primary job hand/wrist responses and between 0.49 and 0.82 for non-work/hobby neck and upper arm scales. These results show potential for future application of similar scales in industry or temporary and seasonal work to evaluate exposure to upper extremity risk factors.

The objective of this study was to compare visual inspection performance of printed circuit boards (PCBs) and flexible circuit boards (flex) when using monovision and autostereovision modes of the Dimension Technologies' Virtual Window TM . We measured completion times for visual inspections of PCBs and flex cards, and detection of manufacturing or post manufacturing defects in each of the products. In the case of printed circuit boards, the stereovision display mode produce faster inspection (approximately 17% improvement in inspection rate) when compared against the monovision mode. No change in inspection performance was observed with flex cards, or in the number of flaws detected, with the introduction of autostereovision. Recommendations are made for improving the effectiveness of the Virtual Window for visual inspection of printed circuit boards and like phenomena.