Comparison of two different methods for performing combination analysis of force and posture risk factors in an epidemiological study.

Objectives: 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.

Methods: 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.

Inter-observer reliability of forceful exertion analysis based on video-recordings.

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.

Interrater reliability of posture observations.

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.

Quantitative exposure-response relations between physical workload and prevalence of lateral epicondylitis in a working population.

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.

Gender adjustment or stratification in discerning upper extremity musculoskeletal disorder risk?

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 health care 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.

Optical properties of plane and convex mirrors: investigation of mirror use to enhance construction flagger safety.

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.

Assessment of perceived injury risks and priorities among truck drivers and trucking companies in Washington State.

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.

Rotator cuff syndrome: personal, work-related psychosocial and physical load factors.

Objective: To identify factors associated with rotator cuff syndrome (RCS) among active workers.

Methods: 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.

Estimating the effectiveness of ergonomics interventions through case studies: implications for predictive cost-benefit analysis.

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.

Application of the Strain Index in multiple task jobs.

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.

Reliability and validity assessment of the hand activity level threshold limit value and strain index using expert ratings of mono-task jobs.

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.

Two posture analysis approaches and their application in a modified rapid upper limb assessment evaluation.

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.

Field evaluation of a new grocery checkstand design.

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.

An assessment of gases in oxygen-deficient hay silos and the effects of forced ventilation.

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.

A survey of tractors and rollover protective structures in Washington State.

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.

Work-related deaths in Washington State, 1998-2002.

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.

Quantifying repetitive hand activity for epidemiological research on musculoskeletal disorders--part II: comparison of different methods of measuring force level and repetitiveness.

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).

Quantifying repetitive hand activity for epidemiological research on musculoskeletal disorders--part I: individual exposure assessment.

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.

Calibrating Borg scale ratings of hand force exertion.

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.

Self-reported musculoskeletal symptoms and observed risk factors in bareroot tree nurseries.

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.

Comparison of ergonomist, supervisor, and worker assessments of work-related musculoskeletal risk factors.

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.

A practical method for ergonomic and usability evaluation of hand tools: a comparison of three random orbital sander configurations.

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.

Comparison of self-report, video observation and direct measurement methods for upper extremity musculoskeletal disorder physical risk factors.

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.

Reproducibility of a self-report questionnaire for upper extremity musculoskeletal disorder risk factors.

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.

An ergonomic characterization of work in concrete form construction.

Concrete formwork construction was identified as the area of greatest ergonomic risk in unionized carpentry by both managers and unionized carpenters. Ergonomic risks were identified and characterized using (a) 1220 randomized work samples from videotape, (b) 82 worker discomfort surveys, (c) on-site observation, and (d) labor-management focus group discussions. Results showed that carpenters spent over 40% of the day in a forward torso flexion posture and over one-third of the day working at or below knee level.