PEO (portable ergonomic observation method)

Transcription

1 PEO 1(5) PEO (portable ergonomic observation method) General description and development of the method The method is based on continuous observation of workers at workplace. Every time the worker adopts a new predefined posture (or action) or moves from one posture to another, the observer hits the predefined keys and the software records the start time of the event. When the posture changes, or when the activity terminates, the observer again hits the same keys. This triggers the software to calculate and store the duration for this particular event. From this information, anchored in real time, the software calculates frequency and duration of each observed item for the observation period. If the frequency and/or total time of the observed task is known, the software calculates the cumulative frequency and duration of postures or actions for a longer periods (day/ week). The information on daily frequency of tasks needed for the calculation of cumulative eposures is received by interviews or production output. The aim was to develop an observational computerized method based on the following requirements: observations made in real time directly at the workplace; data accessible for immediate analysis and presentation; method applicable independently of the subject s profession and work tasks; moderate human resources required for data collection and analysis; a compiled description of physical eposure obtained by combining several work tasks according to their prevalence. Developed in the Swedish National Institute of Occupational Health in the beginning of 1990s for the Stockholm Music population study (Fransson-Hall 1995, Karlqvist 1994) A furhter application for the observation of hand actions Hand PEO (Fransson-Hall 1996) Eposure descriptors posture Eposure Description of eposure magnitude/ amplitude catgories based on angles from neutral posture. Two to three categories for hands, neck, trunk and knees duration frequen cy... movements Change from one position to the other... (eternal) force 5 categories by weights handled... vibration No (possible to include as a new item)... contact forces No (possible to include as a new item)... The original PEO software computes the frequency (number of events during the recording period) for all events and duration (total time of the event) for all events ecept Lift or Etra event. The internal clock is used to record observations in real time, to the nearest tenth of the second

2 PEO 2(5) Resource demands and usability Equipment needed Computer with PEO software. Force gauge and/or scale to measure weights and forces handled. The original software was developed in the former Swedish National Insitute of Working Life and it is not any more available Process of coding and analysis Data collected directly to the computer by pressing the keys when the items change. The software calculates several distributions. Output type/level (risk assessment) Daily or weekly duration of and frequency of tasks are used as weights to give distribution and frequency of them for periods longer than observed. Output of the software can be used as input for additional data handling Criteria to help the evaluator to make decision Predefined postures and weights handled serve as criteria for observational categories. No rules for interpretation of results because the mehtod was developed for research purposes. Fields of the working life where the method has been used Furniture movers, medical secretaries, general population (Fransson-Hall 1995); (Karlqvist 1994) Automobile assembly (Hand PEO, PEO-fle) (Fransson-Hall 1996, Fredriksson 2001) Forest industry (Viikari-Juntura 1996) Schoolchildren (Murphy 2002, Murphy 2004) Dentist (Rolander 2005) Neck movements in occupational use of all-terrain vehicles (Rehn 2005) Validity Face validity / Contents validity Does the method seem to be valid for the aimed purpose? yes 1. The contents of the method is such that a relevant assessment can be epected Comments: The wrist positions are not assessed, and the movements are only categorised as repetitive or not. 2. Items to be observed have a sound basis 3. Sound operationalization of the items to be observed Comments: The definition of neck fleion is vague. It is not obvious if it is related to the fleion of the head relative to the line of gravity, or to the fleion of the neck, regarded as the (distributed) joint between the upper back and the head. The reference position for defining zero

3 PEO 3(5) degrees of fleion/etension is not defined. 4. Sound process to collect data Comments: It is questionable if an observer can manage to consider all aspects of eposure for tasks with rapidly changing postures. 5. Sound process to get the output of the collected data Comments: Duration and frequency, as well as the sequence of the postures are reported. 6. Output can help in decision making Comments: Raw data to be further processed. No advice to guide decision making. The effect of movements as a risk factor may be overlooked. Concurrent validity How well does the method correspond with more valid method/s? 1. Observations vs reference values from video (Fransson-Hall 1995) (Results p , tables 4-5) Observations of duration had higher agreement than observations of frequency 2) PEO vs. technical measures (Leskinen 1997) (results p.80-81) Optoelectronic measurements in a laboratory simulation The difference between observations and measurements were largest for neck fleion 3) PEO vs. technical measures (Karlqvist 1994) (results p.324 and Fig. 2) Prevalence of trunk fleion during work in general population compared to continuous measures with inclinometer "Predictive validity" How well has the risk-estimation of the method been shown to be associated with or predicting musculoskeletal disorders (MSDs)? Association between postures and low-back pain among schoolchildren. (Murphy 2004) (crosssectional study) Postures of neck associated with discomfort among dentists. For the other body parts only weak association (Rolander 2005) (cross-sectional study) Intra-observer repeatability (within observers) 1) Comparison of observations made in two occassions from video (Fransson-Hall 1995) (results p. 97) 2) Intra-obser repeatability for neck movements (Rehn 2005) (results p. 273)

4 PEO 4(5) Inter-observer repeatability (between observers) 1) Comparison of observations made in two occassions from video (Fransson-Hall 1995) (results p. 97, Tab. 6) Conclusions Strengths of the method The method enables the registration of posture duration. The data allows further analysis for different purposes The posture assessments are in generic form, and principally possible to validate by technical measurements Limitations in the use of the method Software not available Time-consuming if detailed data is needed. If the workpace is rapid, the assessment of several eposure categories is not possible. It is impossible to register the right and left hands separately unless the work task is slow and sedentary. Hand postures are not included. The estimates of movements are limited to the occurrences of repetitive movements of the forearm/wrist/fingers performed several times/min. Whole-day observations are not practical. To whom can this method be recommended? For research References Fransson-Hall C &al. Characteristics of forearm-hand eposure in relation to symptoms among automobile assembly line workers. Am J Ind Med. 1996;29(1): Fransson-Hall C &al. A portable ergonomic observation method (PEO) for computerized on-line recording of postures and manual handling. Appl Ergon. 1995;26(2): Fredriksson K &al. The impact on musculoskeletal disorders of changing physical and psychosocial work environment conditions in the automobile industry. International Journal of Industrial Ergonomics. 2001;28(1): Karlqvist L &al. Direct measurements and systematic observations of physical workload among medical secretaries, furniture removers and male and female reference populations. Applied Ergonomics. 1994;25(5): Leskinen T &al. Validation of Portable Ergonomic Observation (PEO) method using optoelectronic and video recordings. Appl Ergon. 1997;28(2): Murphy S &al. The use of the portable ergonomic observation method (PEO) to monitor the sitting posture of schoolchildren in the classroom. Appl Ergon. 2002;33(4): Murphy S &al. Classroom posture and self-reported back and neck pain in schoolchildren. Appl Ergon. 2004;35(2):

5 PEO 5(5) Rehn B &al. Whole-body vibration eposure and non-neutral neck postures during occupational use of all-terrain vehicles. Ann Occup Hyg. 2005;49(3): Rolander B &al. Perceived contra observed physical work load in Swedish dentists. Work. 2005;25(3): Viikari-Juntura E &al. Validity of self-reported physical work load in epidemiologic studies on musculoskeletal disorders. Scand J Work Environ Health. 1996;22(4):251-9.