Macroergonomic Methods
3.1 Background and Applications
3.2 Procedure ... 3-4 3.3 Advantages ... 3-5 3.4 Disadvantages ... 3-5 3.5 Example... 3-5 3.6 Related Methods... 3-5 3.7 Standards and Regulations ... 3-6 3.8 Approximate Training and Application Time... 3-6 3.9 Reliability and Validity... 3-6 3.10 Tools Needed ... 3-7 References ... 3-7
3.1 Background and Applications
The Swedish Work Environment Act stipulates that the employer shall investigate occupational injuries, draw up action plans, and organize and evaluate job modifications. Hence it is also of interest for the government’s Labour Inspectorate to study conditions and improvements in the workplace.
The “method for the identification of musculoskeletal stress factors which may have injurious effects”
(PLIBEL) was designed to meet such needs (Figure 3.1). PLIBEL has been used in several studies, in practical on-site ergonomic work, and as an educational tool. It has been presented in various parts of the world and translated into several languages (Kemmlert, 1995, 1996a, 1996b, 1997).
PLIBEL is a simple checklist screening tool intended to highlight musculoskeletal risks in connection with workplace investigations. Time aspects as well as environmental and organizational considerations also have to be considered as modifying factors.
The checklist was designed so that items ordinarily checked in a workplace assessment of ergonomic hazards would be listed and linked to five body regions (Figure 3.1). Only specific work characteristics, defined and documented as ergonomic hazards in scientific papers or textbooks, are listed (Figure 3.2 and Figure 3.3). Whenever a question is irrelevant to a certain body region, and/or if documentation has not been found in the literature, it is represented by a gray field in the checklist and need not be answered.
The list was made in 1986, and new references have since then been read continuously and the list updated. Mostly, these only add knowledge to the primary list, which accordingly has not been changed.
Kristina Kemmlert
National Institute for Working Life
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3-2 Handbook of Human Factors and Ergonomics Methods
FIGURE 3.1The PLIBEL form.
Method of application. * Find the injured body region. * Follow white fields to the right. * Do the work tasks contain any of the factors described? * If so, tick where appropriate. Also take these factors into consideration: a) the possibility to take breaks and pauses b) the possibility to choose order and type of work tasks or pace of work c) if the job is performed under time demands or psychological stress d) if the work can have unusual or unexpected situations e) presence of cold, heat, draught, noice, or troublesome visual conditions f) presence of jerks, shakes, or vibrations Kemmlert, K. and Kilbom, A. (1986) National Board of Occupational Safety and Health, Research Department, Work Physiology Unit, 17184 Solna, Sweden 7. Is fatiguing foot-pedal work performed? 8. Is fatiguing leg work performed, e.g,: a) repeated stepping up on stool, step, etc.? b) repeated jumps, prolonged squatting, or kneeling? c) one leg being used more often in supporting the body?
1. Is the walking surface uneven, sloping, slippery, or nonresilient? 6. (If the work is performed while standing) Is there no possibility to sit and rest?5. Is the working chair poorly designed or incorrectly adjusted?4. Is the working height incorrectly adjusted?3. Are tools and equipment unsuitably designed for the worker or the task?2. Is the space too limited for work movements or work materials? 9. Is repeated or sustained work performed when the back is: a) mildly flexed forward? b) severely flexed forward? c) bent sideways or mildly twisted? d) severely twisted? 10. Is repeated or sustained work performed when the neck is: a) flexed forward? b) bent sideways or mildly twisted? c) severely twisted? d) extended backward? 11. Are loads lifted manually? Notice factors of importance as: a) periods of repetitive lifting e) handling beyond forearm length b) weight of load f) handling below knee height c) awkward grasping of load g) handling above shoulder height d) awkward location of load at onset or end of lifting 12. Is repeated, sustained, or uncomfortable carrying, pushing, or pulling of loads performed? 13. Is sustained work performed when one arm reaches forward or to the side without support? 14. Is there repetition of: a) similar work movements? b) similar work movements beyond comfortable reaching distance? 15. Is repeated or sustained manual work performed? Notice factors of importance as: a) weight of working materials or tools b) awkward grasping of working materials or tools 16. Are there high demands on visual capacity? 17. Is repeated work, with forearm and hand, performed with: a) twisting movements? c) uncomfortable hand positions? b) forceful movements? d) switches or keyboards?
2. 3.
2. 3.
2.
1. 3.
2.
1. 3. 6. 7. 8. a b c
6.
2.
1. 3. 4. 5. 6. 12.
7. 8. a b c
8. a b c 9. a b c d
4. 5. 9. a b c d 10. a b c d 11. a e b f c g d
11. a e b f c g d 17. a c b d
12.12. 13. 16.14. a b 15. a b
14. a b 15. a b
neck/shoulders, upper part of back elbows, forearms handsfeetknees and hipslow back
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PLIBEL — The Method Assigned for Identification of Ergonomic Hazards 3-3
FIGURE 3.2 Documented background for PLIBEL. References, as numbered in the footnote, are given for each risk factor in relation to body regions, as in the PLIBEL form. Note, however, that in this presentation the distribution is by four body regions. Hips, knees, and feet are combined in the table.
Item 1 2
1 1
3 3
36 36 36 36 10
7 44
11 12 14 12 36 55 62 12 36 29 62 23
53 21
43 55 62
36 57
47 55 58 21
21 57
23 34 43 57
34 17 54
41 47 57 1 4 11 14 29
61
47 62
62 4 11 14 16 21 34 1 4 14 21 29 62 1 21
1 7
34 41 1 11 22 33
57 62 37
7 9 7 9 18 60
48
23
23 31 52 58 61 16
4 14 21 55 62 1
18 31 52 55 58 1
23 31 52 58 60 18
31 52 58 60 61 23
23 31 52 60 61 16
23 31 52 60 61 16
55 11
48 53 15 15 15 48
48 48
58 54 56 56
56 56 56
56 26 38 26 2
30
15 28
19 38
38
38 49 38
38 8 8
49 40
44 28 39
39 56 56 56 56 48 48 48 39 39 39 15 26
26 26 26 15 15 15 3 3 3 28 2 49 63
15 15 15 30 30
30 9 9 9 63
11 11
12
12 11 12
21
3 9
9 11 11
12 12
21 21 3
4 5 6 7 8a 8b 8c 9a 9b 9c 9d 10a 10b 10c 10d 11a 11b 11c 11d 11e
14a 14b 15a 15b 17a 17b 17c 17d 16 11f 11g 12 13
Neck/shoulders, upper part of back
Original papers Review papers and text books
1 Aaras 1987 21 Kvarnström 1983 42 Bongers et al. 1993 2 Anderson 1984 22 Laville 1968 43 Chaffin 1973
3 Bhatnager et al. 1985 23 Luopajärvi et al. 1979 44 Chaffin and Andersson 1984 4 Bjelle et al. 1981 24 Magnusson 1991 45 Enander 1984
5 Bovenzi 1991 25 Mathiassen 1993 46 Gerune et al. 1993 6 Chen 1991 26 Punnett et al. 1991 47 Hagberg and Wegman 1987 7 Drury 1985 27 Riihimaki 1990 48 Jørgensen and
Biering-Sørensen 198 8 Felson 1988 28 Ryan 1989 49 Jørgensen et al. 1993 9 Grandjean et al. 1983 29 Sakakibara et al. 1987 50 Karasek and Theorell 1990 10 Harms-Ringdahl 1986 30 Shute and Starr 1984 51 Lloyd 1986
11 Hünting et al. 1980 31 Silverstein et al. 1986 52 Mital and Kilbom 1992 12 Hünting et al. 1981 32 Sköldström 1987 53 Mital et al. 1993 13 Johansson and Aronsson
1980 33 Starr et al. 1985 54 Pedersen et al. 1992 14 Jonsson et al. 1988 34 Stenlund et al. 1993 55 Rempel et al. 1992 15 Keyserling et al. 1988 35 Sundelin 1992 56 Riihimaki 1991 16 Kilbom 1994a 36 Tola et al. 1988 57 Sommerich et al. 1993 17 Kilbom et al. 1984 37 Vanden Bossche
and Lahaye 1984 58 Stock 1991 18 Kilbom et al. 1991 38 Vingard et al. 1991 59 Sundström-Frisk 1990 19 Kivimaki et al. 1992 39 Vink et al. 1992 60 Tichamer 1978 20 Kjellberg et al. 1992 40 Winkel and Ekblom 1982 61 Wallace and Buckle 1987
41 Örtengren et al. 1982 62 Winkel and Westgaard 1992 63 Hansen, Winkel and
Jörgensen 1998 Elbows, fore-
arms, hands
Hips, knees,
feet Low back
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3-4 Handbook of Human Factors and Ergonomics Methods
Only one — concerning hips, knees, feet, and the lower spinal region — has the kind of new information searched for and has therefore been added to the documented background (Figure 3.2).