Judy Village

Process and implementation of participatory ergonomic interventions: a systematic review

Participatory ergonomic (PE) interventions may vary in implementation. A systematic review was done to determine the evidence regarding context, barriers and facilitators to the implementation of participatory ergonomic interventions in workplaces. In total, 17 electronic databases were searched. Data on PE process and implementation were extracted from documents meeting content and quality criteria and synthesised. The search yielded 2151 references. Of these, 190 documents were relevant and 52 met content and quality criteria. Different ergonomic teams were described in the documents as were the type, duration and content of ergonomic training. PE interventions tended to focus on physical and work process changes and report positive impacts. Resources, programme support, ergonomic training, organisational training and communication were the most often noted facilitators or barriers. Successful PE interventions require the right people to be involved, appropriate ergonomic training and clear responsibilities. Addressing key facilitators and barriers such as programme support, resources, and communication is paramount. Statement of Relevance: A recent systematic review has suggested that PE has some effect on reducing symptoms, lost days of work and claims. Systematic reviews of effectiveness provide practitioners with the desire to implement but do not provide clear information about how. This article reviews the literature on process and implementation of PE.

Measuring posture for epidemiology: Comparing inclinometry, observations and self-reports

The objective of this study was to use and evaluate three postural assessment methods for epidemiological studies of back disorders. The methods were: (1) a data-logging inclinometer; (2) observations by trained observers; (3) self-reports by employees. All methods were feasible in 50 heavy industry worksites. Inclinometry provided quantitative measures of flexion–extension (mean 17°, SD 11.2°), lateral flexion (mean 8.5°, SD 2.6°) and trunk movement speed (mean 14.3° per second, SD 4.9° per second). Observations and self-reports provided estimates of time spent in various trunk angles, general postures, materials handling and vehicles. Compared to observations, self-reports under-reported less common tasks, but over-reported task durations. In statistical modelling to determine if observations or self-reports could be used to estimate measured postures, observations accounted for 30 to 61% of the inclinometer measurement variance and self-reports for 33 to 40%. A combination of inclinometry and observations would be an ideal option to provide both depth and breadth of data on postures and other physical exposures for epidemiological research.

Workload as a Determinant of Staff Injury in Intermediate Care

Abstract Care aides (CAs) and licensed practical nurses (LPNs) in intermediate care (IC) facilities experience high risks of injury. Workload measures were examined in eight IC facilities to ascertain their relationships with musculoskeletal injury rates, pain, burnout, and selfreported health. Workload was measured using 1) focus groups and telephone interviews to obtain CA/LPN perceptions; 2) systematic observation (numbers of tasks performed in shift); and 3) CA-to-resident staffing ratios. Controlling for resident dependency and facility funding, all workload measures were correlated with staff injury rates and burnout. Facilities with low injury rates had better CA/LPN-to-resident staffing ratios and fewer tasks. The differences in staffing reflected differences in how organizations prioritized and allocated resources. Thus, workload is an important determinant of injuries and increased staffing evels correlate with decreased injuries.

Development and evaluation of an observational Back-Exposure Sampling Tool (Back-EST) for work-related back injury risk factors

We developed and evaluated an observational Back-Exposure Sampling Tool. A literature review suggested 53 exposure variables; these were reduced to 20 following field trials. Kappas for agreement beyond chance between six observers assessing exposures in 72 photos ranged from 0.21 to 1.0, with the highest values for posture type, trunk angle, manual materials handling, hands on item, and load weight. Intraclass correlations for agreement between pairs observing 17 workers once per minute for a full-shift were >0.74 for most postural, trunk angle, and manual materials handling variables. In validity testing, the proportions of shifts in flexion/extension and lateral bending observed for 169 full-shifts were compared to inclinometer measurements. Pearson correlations were 0.42 for 45-60 degrees flexion and 0.9 for >60 degrees flexion, but only 0.11-0.19 for lateral bending and trunk flexion less than 45 degrees . When lower flexion angles were collapsed to include trunk extension, correlations increased to >0.5.

Assessing whole body vibration exposure for use in epidemiological studies of back injuries: measurements, observations and self-reports

Improved assessment of whole body vibration exposure is needed for epidemiological studies investigating the causes of low back disorders. Vibration was measured on 54 worker-days in five heavy industries, with data collected on observed and self-reported driving conditions, demographics, and vehicle characteristics. Variables significant at p < 0.1 in simple linear regressions (20 of 34) were retained for mixed effects multiple regressions to determine the best prediction of rms vibration level and 8-h equivalent vibration exposure. Vibration was measured, on average, for 205 min per work shift (SD 105). Means and standard deviations in m · s−2 were: x-axis 0.35 (0.19); y-axis 0.34 (0.28); z-axis 0.54 (0.23); vector sum 0.90 (0.49); and 8-h equivalent vector sum 0.70 (0.37). The final three regression models retained only 2 or 3 of the 34 variables (driving speed (<20 km/h and/or 20–40 km/h) and industry and/or vehicle type and explained up to 60% of the variance (R 2 = 0.26–0.6). Practitioner summary The purpose of the project was to create a model that can predict whole body vibration exposure from a number of observed or self-reported variables. This could eliminate the need for costly and time-consuming field measurements of WBV in epidemiological studies. Despite a large number of variables included in the model (34) and 54 worker-days of WBV measurement, the final models contained only two or three variables, and explained 60% of the variance. While this is an improvement over use of job title in epidemiological studies, it still leaves a considerable amount of WBV variance unexplained.

Factors Associated With Staff Injuries in Intermediate Care Facilities in British Columbia, Canada

Background:Large variations in staff injury rates across intermediate care facilities suggest that injuries may be driven by facility-specific work environment factors. Objectives:To identify work organization, psychosocial, and biomechanical factors associated with staff injuries in intermediate care facilities, to pinpoint management practices that may contribute to lower staff injuries, and to generate a provisional conceptual framework of work organization characteristics. Methods:Four representative intermediate care facilities with high staff injury rates and four facilities with comparable low staff injury rates were selected from Workers’ Compensation Board (WCB) databases. Methods included on-site injury data collection and review of associated WCB data, ergonomic study of workloads, a telephone survey of resident care staff, manager-staff interviews, and focus groups. Pearson product-moment correlation coefficients identified associations between variables. Analysis of variance and t tests were used to determine differences between low and high staff injury rate facilities. Content analysis guided the qualitative analysis. Results:There were no significant differences between low and high staff injury rate facilities in terms of workers’ characteristics, residents’ characteristics, and per capita public funding. The ergonomic study supported the survey data in demonstrating a relation among low staffing levels, greater muscle loading, and greater risk of injury. As compared with facilities that had high staff injury rates, facilities with low staff injury rates had significantly more favorable staffing levels and supportive work environments. Perceived quality of care was strongly correlated with burnout, health, and satisfaction. Conclusions:Safer work environments are promoted by favorable staffing levels, convenient access to mechanical lifts, workers’ perceptions of employer fairness, and management practices that support the caregiving role.

How Long Is Long Enough? Evaluating Sampling Durations for Low Back EMG Assessment

Few ergonomic measurement tools explicitly state when and how to sample exposures. Traditional ergonomic sampling has used short, task-based or worst-case measurements, but these may misrepresent exposures, since they neglect the temporal variations throughout the workday. Understanding the representativeness of data from shorter measurement durations compared with full-shift measurements allows for optimization of measurements resources. This study compared a variety of low back electromyography (EMG) exposure metrics measured over a full-shift with the same metrics sampled over shorter durations to identify whether shorter durations provide representative measures of exposure. Portable EMG devices were used to measure low back EMG for 138 full work shifts in a range of jobs in heavy industry. Using a random start time, each full shift of data was resampled for 4 hr, 2 hr, 1 hr, 10 min, and 2 min. Exposure metrics from each duration were compared with the full shift using absolute and percent error, bias, and limits of agreement. Comparisons between one full shift and two full shifts were made for the subset of 35 workers with two measured workdays. Compared with full-shift data, bias is very low at all sampling durations. However, as sampling durations decreased from a full-shift to a few min, the absolute error, percentage error, and limits of agreement for exposure estimates show more deviation from full-day estimates. Estimates of mean and 90th percentile exposure averaged 8% error for 4-hr durations and 14% error for 2-hr durations. The errors for 4-and 2-hr measurement durations may be acceptable for many applications, particularly if the trade-off is measuring more subjects. Sampling durations of 1 hr or less seem likely to produce very large errors over all exposure metrics, particularly for the range and peak exposures. Depending on the purpose of measurement and the detail required, 4 hr or even 2 hr appears to be long enough to reasonably estimate full-shift exposure.

Biomechanical comparison of carpet-stretching devices

Peak impact forces, measured from seven male carpetlayers using a knee-kicker over 39 trials were 2933 N (SD 397), taking 9.5 ms (SD +/- 1.1) to reach peak. The knee-kicking cycle involved high knee decelerations of 880 m.s-2 (SD +/- 271). Angles at peak force for the knee (63 degrees SD +/- 10 degrees) and hip (80 degrees SD +/- 35 degrees) showed considerable variation between individuals. Kneeling forces on the non-kicking leg during the kick cycle were 894 N: comparative forces were 368 N and 476 N measured during use of the power stretcher and crab re-stretcher, respectively. Under dynamic conditions the effective mechanical advantage of the knee-kicker was less than 1.0. In comparison, the mechanical advantage of the power stretcher was approximately 14 times greater over the stretch action. When tested with a crab re-stretcher, the breaking strength of the smooth-edge to which the carpet attaches averaged 2384 N (SD +/- 245). Design guidelines for an improved carpet stretching device are provided.

Design-for-human factors (DfHF): a grounded theory for integrating human factors into production design processes

The ‘design for human factors’ grounded theory explains ‘how’ human factors (HF) went from a reactive, after-injury programme in safety, to being proactively integrated into each step of the production design process. In this longitudinal case study collaboration with engineers and HF Specialists in a large electronics manufacturer, qualitative data (e.g. meetings, interviews, observations and reflections) were analysed using a grounded theory methodology. The central tenet in the theory is that when HF Specialists acclimated to the engineering process, language and tools, and strategically aligned HF to the design and business goals of the organisation, HF became a means to improve business performance. This led to engineers ‘pulling’ HF Specialists onto their team. HF targets were adopted into engineering tools to communicate HF concerns quantitatively, drive continuous improvement, visibly demonstrate change and lead to benchmarking. Senior management held engineers accountable for HF as a key performance indicator, thus integrating HF into the production design process. Practitioner Summary: Research and practice lack explanations about how HF can be integrated early in design of production systems. This three-year case study and the theory derived demonstrate how ergonomists changed their focus to align with design and business goals to integrate HF into the design process.

Using observation and self-report to predict mean, 90th percentile, and cumulative low back muscle activity in heavy industry workers

Occupational injury research depends on the ability to accurately assess workplace exposures for large numbers of workers. This study used mixed modeling to identify observed and self-reported predictors of mean, 90th percentile, and cumulative low back muscle activity to help researchers efficiently assess physical exposures in epidemiological studies. Full-shift low back electromyography (EMG) was measured for 133 worker-days in heavy industry. Additionally, full-shift, 1-min interval work-sampling observations and post-shift interviews assessed exposure to work tasks, trunk postures, and manual materials handling. Data were also collected on demographic and job variables. Regression models using observed variables predicted 31-47% of the variability in the EMG activity measures, while self-reported variables predicted 21-36%. Observation-based models performed better than self-report-based models and may provide an alternative to direct measurement of back injury risk factors.