Workstation layout and work postures at call centres in Sweden

ARTICLE IN PRESS
International Journal of Industrial Ergonomics 38 (2008) 1051– 1061
Contents lists available at ScienceDirect
International Journal of Industrial Ergonomics
journal homepage: www.elsevier.com/locate/ergon
Workstation layout and work postures at call centres in Sweden in relation
to national law, EU-directives and ISO-standards, and to operators’ comfort
and symptoms
Allan Toomingas a,,1, Désirée Gavhed b,1
a
b
Division of Occupational and Environmental Medicine, Department of Public Health Sciences, Karolinska Institutet, SE-171 77 Stockholm, Sweden
Division of Childhood Cancer Research, Department of Woman and Child Health, Karolinska Institutet, Sweden
a r t i c l e in fo
abstract
Article history:
Received 22 July 2007
Received in revised form
5 February 2008
Accepted 18 February 2008
Available online 18 April 2008
A survey of workstation layout and work postures among 156 computer operators was performed in 16
call centers (CCs) in Sweden, relating data to operators’ comfort, symptoms and existing ISO-standards,
EU-directives and National Work Environment Law.
The quality of the furniture and equipments was generally good and mainly fulfilled the demands of
the law, directives and standards. The main problem was how these were used—how they were
positioned and adjusted to fit the individual operator and to allow good and flexible work postures.
Awkward postures were, therefore, seen in shoulder joints and wrists. Lack of easy height adjustability
of many desks was noted. This was associated with more seated postures and back pain. Desk and chair
quality were associated with operators’ satisfaction and work postures and thick keyboards with
dissatisfaction and neck or back pain. Optimal adjustments were associated with operators’ satisfaction
and good work postures and in some aspects also with fewer symptoms. The conditions were more
optimal at internal CCs as opposed to freestanding external (outsourced) enterprises.
Keywords:
Office
Computer work
Ergonomics
ISO-standards
EU-directives
Work environment law
Relevance to industry
CCs are one of the fastest expanding business sectors. Besides, investments in more flexible desks,
optimizing basic adjustments would improve conditions substantially in many cases. There is thus a
potential for improvements in the conditions for CC work with possibilities for gain in comfort, health
and productivity.
& 2008 Elsevier B.V. All rights reserved.
1. Introduction
More than 1% of the European working population is estimated
to work in call centres (CCs) (Datamonitor, 1998). Total agent
positions in Europe, Middle-East and Africa were expected to grow
from 1.5 million at the end of 2003 to 2.1 million by 2008
(Datamonitor, 2004). CCs handle telephone calls, both inbound,
e.g. customer support, and outbound, e.g. sales or market survey.
Multimedia communication for this handling (fax, e-mail, SMS
and web chat) is rapidly growing within the business. The
character and content complexity of the services vary from
simple, such as information desk (e.g. phone directory) and
Corresponding author. Tel.: +46 8 737 39 60; fax: +46 8 33 43 33.
E-mail address: [email protected] (A. Toomingas).
At the time of the study both worked at the Department for Work and
Health, National Institute for Working Life, Sweden.
1
0169-8141/$ - see front matter & 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.ergon.2008.02.010
booking services, to complex, such as computer support, economical and medical advice.
The number of reports about adverse working conditions in
CCs has increased rapidly since the middle of the 1990s. Aspects of
both the organization of work, psychosocial issues, ergonomics
and other environmental issues have been focused on (Bain et al.,
2002; Dieckhoff et al., 2001; Ferreira and Saldiva, 2002; Hoekstra
et al., 1995; Norman et al., 2004; Sprigg et al., 2003). Physical
working conditions have recently been reported indicating that
the conditions quite often are out of range of current directives
and recommendations for sound working environment (Gavhed
and Toomingas, 2007).
Awkward work postures and factors in the computer work
environment may cause or aggravate musculoskeletal disorders
(Hildebrandt et al., 2002; Karlqvist et al., 2002; Norman, 2005;
Punnett and Bergqvist, 1997). Office furniture and equipment of
high quality are thus important, but also how they are positioned
and adjusted.
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Few studies on qualities of office furniture and information and
communication technology (ICT) at CCs have been published in
the peer-reviewed scientific literature. Existing studies have been
restricted regarding the selection of CCs. This scarcity of studies in
the international literature also applies to the situation in Sweden.
One complication is that neither does a national register exist nor
any other comprehensive source of information about CC
enterprises or CC employees in Sweden. Thus, there is no
possibility to obtain a statistically representative sample of CCs
or their employees. One way to increase the external validity of
studies of CCs is to make a strategic sample such that companies
are selected to cover a wide range of the potentially important
organizational models and exposure conditions. One important
organizational aspect is whether the CC is an external independent company offering its service to other organizations (EXCC) or
internal within an organization handling its customer service
matters (INCC) (Batt et al., 2005). INCC have been found to have
somewhat better physical working conditions (Gavhed and
Toomingas, 2007).
A study of health and working conditions at customer service
work in strategic sample of Swedish CCs was, therefore, initiated
and performed. The study was part of a cross-sectional project
where many aspects of work and health among 1183 CC workers
were studied (Norman, 2005). The present study adds to earlier
reports about physical and other working conditions and musculoskeletal disorders at these CCs (Gavhed and Toomingas, 2007;
Norman et al., 2008; Toomingas and Hansson Risberg, 2007).
2. Aim
The aim of this study was to describe the workstation layout
and work postures at a strategic sample of Swedish INCCs and
EXCCs, and relate them to existing national law, EU-directives and
ISO-standards, and to operator’s comfort and symptoms.
3.3. Observations and measurements
Following a checklist that had been tested for interrater
reliability, trained ergonomists made observations and measurements of the workstations (Table 2, 3) and the operators’ work
postures (Table 5) during a regular workday when they performed
typical tasks (Norman et al., 2006; Toomingas, 2008b). Observations were made only during customer calls. The checklist
included measurements of the office furniture, properties and
positioning of the ICT-equipment. Postures of the upper body
were observed and categorized according to previous studies
(Lindegård et al., 2005). Postures were measured as shown in
Fig. 1. The viewing angle between a horizontal line and the line
from the eye to the upper and lower edge of the display, were
estimated using a manual goniometer with a laser beam. The
observations took about 15 minutes/workstation.
During the workday (about 8 h) a portable data-logger
(Posimeter, Biolin AB, Mölndal, Sweden) recorded seated standing/walking postures, defined as the thigh angle against vertical.
The aggregated total duration of the positions above (seated) and
below (standing/walking) 451, respectively, was registered
(threshold 3 s; sampling frequency ¼ 3 Hz).
The observed qualities of the workstations were compared
with relevant parts of the Swedish Work Environment Law (SWEA,
1998) and the Directives of the European—90/270/EEC (EU, 1990)
and also to recommendations given in international standards—
EN 527-1:2000 (CEN, 2000), EN 527-1:2000/AC:2002 (CEN, 2002)
and ISO 9241.4 and 5 (ISO, 1998, 1999).
3.4. Medical interview
3. Methods
A physician asked the operators by using standardized
questions, if they had experienced pain or other symptoms at
least once a week during the last month in the following five
regions of the body: (1) head; (2) neck/scapulae; (3) shoulder
joints/upper arms; (4) elbows/forearms, wrists or hands/fingers
and (5) back (thoracic or lumbar).
3.1. Sample of CCs, the study group and workstations
3.5. Data treatment
Sixteen enterprises, six INCC and 10 EXCC, participated in this
study. Among those on duty on the study days, ten operators and
their workstations at each of the 16 companies were randomly
selected and invited to participate in the study whereof 156
participated: 109 women and 47 men (mean age 34.3 yr, sd. 10.8,
range 18–62 yr; median seniority at the CC 1.5 yr, range
0.2–25.8 yr). All workstations except four were located in openplan offices, the largest number in one room being 225. Workstations were frequently shared between operators in different
work shifts. For more details about the CCs, the working tasks and
the selection process—see Gavhed and Toomingas (2007).
The study was approved by the Ethics Committee at the
Karolinska Institutet.
A quality index (0–8) was constructed for chairs by adding
points assigned when: (a) the chair had a swivel function;
(b) backrest supported both lower and upper back; (c) backrest
allowed shoulder extension; (d) backrest inclination and (e) height
could be adjusted; (f) height and (g) width of armrest could be
adjusted; and (h) seat height was adjusted by gas-lift. A similar
index (0–7) was constructed for work desks assigning points when:
(a) height was adjusted by pneumatic or electric control; (b) the
desk surface was even or had a separate surface for the display;
(c) the front edge was concave; (d) the space for the operator’s legs
was adequate and free; (e) the surface for documents was
adequate; (f) there was space to rest at least half of the forearms
on the desk surface at keyboard work and (g) at work with the
pointing device. Seat, armrest or desk height was measured and
those that deviated X75 cm from the optimal, as judged by the
ergonomist, were considered as adjusted too high or low.
A posture index was constructed describing how close to
optimal (neutral) the posture in each observed joint was during
work. The components A–C were summated as 100 (A+B+C)/
maximum, where the maximum was the sum of optimal postures
(Table 1). The index for each joint was used in the analysis of
association with ratings of satisfaction and with symptoms.
Ratings of satisfaction were categorized into: Satisfied ¼ very
or rather satisfied; Neutral ¼ neither dissatisfied nor satisfied,
Dissatisfied ¼ rather or very dissatisfied.
3.2. Questionnaire
A questionnaire was distributed to all operators at the
observed workstations prior to the day of observations (Toomingas, 2008a). Only data relevant to this study are reported here
(question no.38). The operators were asked to rate their opinion
during the past month about their workspace and posture, chair,
desk, VDU, keyboard and pointing devices including their
placement, using a five-point scale with the alternatives: very
satisfied, rather satisfied, neither dissatisfied nor satisfied, rather
dissatisfied and very dissatisfied.
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Differences between INCC and EXCC and differences between
asymptomatic and symptomatic operators were analysed using
chi-square and Fisher’s exact tests for nominal variables
(H2x ; x ¼ df). The Mann–Whitney test (M–W) was used to test
differences in ordinal variables and in unevenly distributed
continuous variables. Finally, Student’s t-test (t) was used to
analyse differences in distance, height and viewing angle.
Tests of associations between ratings of satisfaction, observations or quality index of table/chair were done using the
Spearman’s rho or Goodman–Kruskal gamma statistic (g) if
many ties.
The statistical two tailed significance level, was po0.05.
Results are reported from the whole study group but also
separately from EXCC and INCC. Some measurements of the
placement of equipment on the desk were introduced after
visiting the first CC. Eight observations of the viewing angles
1053
were found to be incorrectly recorded, and were thus excluded
from further calculations.
4. Results
4.1. Observations of the furniture and ict-equipment
Chairs: All chairs had easy (pneumatic) adjustment of seat
height. Many had a swivel function, backrest inclination adjustment (Table 2), and a backrest narrow enough to not interfere
with shoulder extension (77%). Among the 25% of seats that
deviated from the optimal height by X75 cm, all were adjusted
too high (Table 3). Most of the armrests were adjustable for
height, whereof 28% deviated from the optimal height by X75 cm
(23% adjusted too high and 5% too low).
Fig. 1. Measurements of joint angles and observations of body postures among call centre operators. Dotted line ¼ vertical line.
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Fig. 1. (Continued)
Except for adjustability of backrest inclination most chairs
fulfilled the demands of the Swedish Work Environment Law, the
European Directives and ISO standards (Table 2).
The chairs at INCC had a somewhat higher quality index
than at EXCC (median 6.0 vs. 5.0, M–W p ¼ 0.12) (Fig. 2).
More chairs had neck support at INCC (34% vs. 14%) and
more chairs had only support for the lumbar back in EXCC
(20% vs. 4%) (H22 ¼ 12:96, p ¼ 0.002). Further, more chairs
had swivel function at INCC (97% vs. 78%) (H21 ¼ 10:11, p ¼
0.001). No significant differences in deviation between observed
and optimal height of seats or armrests were found between INCC
and EXCC.
Twenty seven percent of the operators were dissatisfied with
their chairs, somewhat more at EXCCs than at INCCs (33% vs.
18%)(H22 ¼ 3:98, p ¼ 0.14).
Desks: About 70–90% of the desks fulfilled the demands of the
Swedish Work Environment Law and the European Directives
(Table 2). About 90% of the desks fulfilled the European standard
for minimum dimensions, 1200 800 cm (CEN, 2002). They were
also judged to be large enough to give adequate space for
documents and equipment and for support of the distal half of
the forearms while at work with the input devices, thus fulfilling
the national and European directives. Somewhat fewer (78%)
fulfilled the demands for adequate free space for legs under the
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Table 1
Scorings of observed working postures in different joints according to Fig. 1
Joint
Score
2
1
0
Neck
Range 0– 6
A
B
C
Extension o51/flexion o151
Rotation o151
No craned neck
ExtensionX51/flexion 15– 301
Rotation 15– 451
–
Flexion 4301
Rotation 4451
Craned neck
Shoulder joint
Range 0– 6
A
B
C
Extension/flexion o151
Abduction o151
Inward rotation p451/outward rotation o151
Extension/flexion 15– 301
Abduction 15– 301
Inward rotation 4451/outward rotation 15– 301
Flexion 4301
Abduction 4301
–
Outward rotation 4301
Wrist
Range 0– 4
A
Extension/flexion o151
Extension 15– 301/flexion X151
Extension 4301
B
Radial deviation o101/ulnar deviation o151
Radial deviation X101/ulnar deviation 15– 301
–
ulnar deviation 4301
A
B
C
Extension/ flexion o151
No lateral flexion
Back not curved
Extension/flexion X151
–
–
–
Lateral flexion
Curved back
Back/spine
Range 0– 6
Score: 2 ¼ optimal posture; 1 ¼ minor deviation from optimal posture; 0 ¼ major deviation from optimal posture. ‘‘Range’’, the minimum and maximum of possible sum of
scores.
desk. As many as 30% of all desks were not easy to adjust for
height, but needed tools or other cumbersome methods.
During the observations 92% of the operators worked in a
seated posture and 8% were standing. The observed desk height
during seated work deviated from the optimal by an average of
4.7 cm (sd. 4.1 range 4 to 17 cm). During standing the average
deviation from optimal was 28.4 cm (sd. 15.4, range: 0.5 to 42.0).
Among the 42% of all desks that deviated from the optimal height
by X5 cm all were adjusted too high.
Generally, the desks at INCC had higher quality index than at
EXCC (median 7.0 vs. 6.0; M–W po0.001) (Fig. 2). EXCC tended to
have less adequate space on and around the desk than did INCC
(Table 2). This was reflected in the ratings as the operators at EXCC
were more dissatisfied than operators at INCC with their workspace (28% vs. 13%, H22 ¼ 5:38, p ¼ 0.07) and desk (28% vs. 7%,
H22 ¼ 9:58, p ¼ 0.008).
No significant difference in deviation between observed and
optimal height of the desks was found between INCC and EXCC.
VDU. CRT displays were more common (71%) than LCD or TFT
displays (29%). No laptop computers were used. Nearly all VDUs
could be tilted (99%) and rotated (97%), following the demands of
the Swedish Work Environment Law and the EU-directives. About
a third of the visual displays were placed outside the recommended range of 50–70 cm given in law, directives and standards
(Table 3). Most of these (92%) were placed too close to the
operator. At 18% of the workstations, the viewing angle to the top
of the display was above 01 (i.e. the horizontal line), opposing the
guidance given in law, directives and standards. The viewing angle
to the lower edge of the display was on average 23.11 (sd. 6.11,
range 40 to 6, n ¼ 130). The average viewing angle to the
middle of the display was 13.21 (sd. 4.71, range ¼ 1 to 241).
Total 11% of the operators were dissatisfied with their visual
display unit and its placement (15% at EXCC; 6% at INCC).
Input devices (keyboard and pointing device): A computer mouse
was used at 92% of the workstations. Mouse was slightly more
frequent at EXCC (96%) than at INCC (86%) (H21 ¼ 4:84, p ¼ 0.03);
12% at INCC had a Mousetrapper (TestLab-System A/S, Roskilde,
Denmark) and 2% used a trackball, compared with 3% and 1%,
respectively, at EXCC.
Every other keyboard and a majority of the pointing devices
were placed outside the shoulders width or forearms’ reach, thus
violating common recommendations (Table 2). Most keyboards
and pointing devices were too close to or too far away from the
front edge of the desk according to the ISO-standard, thus
hampering the possibilities for resting the forearms and wrists
on the desk-top (Table 3). Combining both aspects of recommendations, only 29% of all keyboards and 6% of all pointing devices
were optimally placed on the work desk.
The average keyboards thickness was equal to the maximum
given in the ISO-standard (3.0 cm), and 30% were thicker (Table 3).
Moreover, 59% of the keyboards were tilted forwards by extended
folding legs underneath the back edge, thereby further increasing
the keyboard height and increasing the risk of wrist extension.
Extended keyboard legs were observed more often at EXCC (69%)
than at INCC (33%) (H21 ¼ 14:67, po0.001). The average keyboard
width was 46.1 cm (range: 43.0–52.0 cm). Those at EXCC were
generally wider than at INCC (46.3 cm vs. 45.7 cm) (t ¼ 3.4
df ¼ 154, p ¼ 0.001), thus increasing the risk of awkward shoulder
and wrist postures. No directive or standard exist concerning the
keyboard width.
In contrast to the observations, only a minority of the operators
was dissatisfied with their keyboard (10%) and the pointing device
(18%) and their position on the desk-top (Table 3). No significant
difference in dissatisfaction was found between EXCC and INCC
(keyboard: 12% vs. 7% and pointing device: 17% vs. 20%).
Pointing devices were more often observed to be placed within
shoulders width and forearms reach at INCC compared to EXCCs
(32% vs. 9%; H21 ¼ 12:99, po0.001). A similar tendency was
observed concerning the keyboards (57% vs.44%; H21 ¼ 2:30,
p ¼ 0.09).
4.2. Sitting and standing
The operators were seated during on average 75% of the
measured periods of the work day according to the portable logger
(sd. ¼ 17%; median ¼ 80%; range ¼ 6–95%). The measured periods
were, on average, 351 min (sd. 66 min). About 85% of all operators
were seated more than 60% of the period, and 6% of the operators
were seated 90% of the period or more. The Swedish Work
Environment Authority recommends computer workers to change
between seated and standing work (SWEA, 1998), similar to
International standardization Organization (ISO, 1999). No recommendations for time-limits of seated work exist, however.
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Table 2
Characteristics of office furniture and input devices including their adjustment and their adherence to Swedish law, EU-directives, and ISO-standards
Chair
Height adjustment easya (%)
Backrest inclination adjustableb,c (%)
Backrest supports upper backb (%)
Swivel functiond (%)
Seat pan height (cm)
Mean (sd.)
Median (range)
Armrestsd (%)
Armrests adjustabled for
Height (%)
Width (%)
Armrest height (cm)
Mean (sd.)
Median (range)
Desk
Adequate space for material and equipmentb,c (%)
Separate shelf for displayb,c (%)
Adequate leg spaceb,c (%)
Height adjustment easye (%)
Desk top areaf (m2)
Mean (sd.)
Median (range)
Desk top depthg (cm)
Mean (sd.)
Median (range)
Desk height while seated (cm)
Mean (sd.)
Median (range)
Desk height while standing (cm)
Mean (sd.)
Median (range)
Desk height range, if adjustableh (cm)
Mean (sd.)
Median (min–max)
Input devices
Optimally positionedi:
Keyboard (%)
Pointing device (%)
External (%)
Internal (%)
All (%)
n ¼ 97–98
100
64
80*
78*
n ¼ 58
100
50
93*
97*
n ¼ 155–156
100
59
85
85
52(3)
52(43–58)
64
n ¼ 63
97
41*
n ¼ 60
71(4)
71(63–79)
52(4)
52 (44–61)
78
n ¼ 44–45
91
73*
n ¼ 37
70(4)
70(62–77)
52(4)
52(43–61)
69
n ¼ 107–108
94
54
n ¼ 97
70(4)
71(62–79)
n ¼ 98
83
7*
67*
53*
n ¼ 58
100
31*
95*
100*
n ¼ 156
89
16
78
70
1.6 * (0.45)
1.8 (0.8–2.6)
2.0* (0.41)
2.1 (1.3–2.6)
1.7 (0.47)
1.8 (0.8–2.6)
101.6 ( 15.5)
103 (70–140)
n ¼ 94
74 (3)
73.5 (68–84)
n¼4
105 (6)
104.5 (98–113)
n ¼ 86
36.5(19.1)
46 (9–62)
104.6 (17.3 )
106 (77–130)
n ¼ 49
75 (4)
74.0 (66–92)
n¼9
103 (8)
105.0 (89–115)
n ¼ 51
49.7(5.0)
50 (30–61)
102.7 (16.2)
103 (70–140)
n ¼ 143
75 (4)
73.5 (66–92)
n ¼ 13
103 (7)
105.0 (89–115)
n ¼ 137
41.4(16.7)
49 (9–62)
n ¼ 98
n ¼ 49–56
n ¼ 147–154
44
9
57
32
48
17
Separated for external and internal call centres. Prevalence in % and heights in cm; sd., standard deviation; *, significant difference external–internal call centres, po0.05.
a
Adjustment by pneumatic lift (ISO, 1999).
b
Conceptualization of demands or recommendations in the Swedish Work Environment Law AFS 1998:5 (SWEA, 1998).
c
Conceptualization of demands in the European Council Directives 90/270/EC (EU, 1990).
d
Dynamic seating and adjustable arm rests are recommended, ISO 9241-5 (ISO, 1999).
e
Adjustment by pneumatic lift or electric control (ISO, 1999).
f
Minimum 0.8 1.2 m (0.96 m2); CEN standard 527-1:2000/AC:2002 (CEN, 2002).
g
Recommended min 80 cm; CEN standard 527-1:2000/AC:2002 (CEN, 2002).
h
Recommended min range 20 (60–80) cm; CEN standard 527-1:2000/AC:2002 (CEN, 2002).
i
Placed within shoulder width and forearm’s reach. Prevents shoulder abduction, flexion and outward rotation.
4.3. Postures
During the observation time fewer were standing and varying
between standing/sitting in EXCC than in INCC (6% vs. 19%)
(H21 ¼ 6:19, p ¼ 0.01). Of all of the observed joint postures, the
shoulder joint deviated most frequently (94% of the operators)
from an optimal posture, according to the calculated index values
(Table 4). Non-optimal wrist postures were also common. The
shoulder joint postures were optimal more frequently at INCC
than at EXCC (M–W p ¼ 0.03).
About 70% of the operators were using the pointing device
during the observations of the back, shoulder and extremity
postures, whereas the others used their keyboard. Using either
type of input device awkward postures outside the neutral range
was observed among many operators; shoulder flexion among
45%, abduction 68% and rotation 33% (Table 5). Most operators
using the keyboard were observed to have a mainly neutral
shoulder posture, whereas 46% of the mouse users had an
outward rotation of 4151 and 23% had an 4301 abduction.
During the observation of the neck, nearly all (96%) were
looking at the display. Most of the operators (85%) had optimal
neck postures (Table 4). The 11% of the operators had extended or
flexed neck postures and 10% had a craned neck (Table 5). Only a
few operators (4%) had their neck rotated X15 1 while working, all
at EXCC.
Only 42% had optimal wrist postures (Table 4). Wrist extension
or ulnar deviation X151 were observed in one or both wrists
among about one-third of the operators (Table 5), respectively,
and 10% had both (no difference between keyboard or mouse use).
All together 76% of the operators rested their elbows on the
armrests or the distal half of their forearms on the table surface or
armrest. More operators rested their forearms during mouse use
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Table 3
Ergonomists’ observations of workstations and their adherence to Swedish Work Environment Law, EU-directives, and ISO-standards. Operators ratings of satisfaction with
work postures, furniture and equipment
Measurements
n
Ratings
Mean (sd.)
Median (range)
Proportion outside
recommended range %
Proportion dissatisfied %
(rated aspect)
4.5 (0–42)
3.0 (0–18)
3.0 (0–13)
42a
25b
28a
23 (work posture)
20 (desk)
27 (chair)
–
53.0(24–85)
21.5(0–47)
23.5(2.0–55)
33c
89d
67d
22 (work space)
11 (display)
10 (keyboard)
18 (pointing device)
Difference observed—optimal height (cm)
Desk1
Chair1,2
Armrest
156
153
95
6.7 (8.3)
3.4 (3.1 )
3.5 (2.7)
Distance to desk front edge (cm)
Display1
Keyboard1,2
Mouse/equal1
154
156
147
53.2(9.2)
21.1(9.3)
22.8(11.4)
Keyboard thickness1 (cm)
156
3.0(0.5)
3.0(2.0–4.5)
30e
10 (keyboard)
Display height
Angle eye—upper-edge of display1 (1)
130
3.5 (4.6)
4.0 (15–9)
18f
23 (work posture) 11 (display)
General directives:
1
Conceptualization of demands or recommendations in the Swedish Work Environment Law AFS1998:5 (SWEA, 1998).
2
Conceptualization of demands in the European Council Directives 90/270/EC (EU, 1990).
Specific recommendations/criteria:
a
Desk and armrest height at elbow height; difference observed—elbow heightX75 cm (ISO, 1999).
b
Seat pan height at popliteal height; difference observed—popliteal heightX75 cm (ISO, 1999).
c
Visual display placed 50–70 cm from front desk edge (modified from ISO, 1999).
d
Keyboard and mouse placed 10–20 cm from front desk edge (ISO, 1999).
e
Keyboard height should not exceed 3 cm (ISO, 1998).
f
Angle between the eye and the upper-edge of displayo0 1 (ISO, 1999).
Number of chairs
30
EXCC
25
INCC
20
15
10
5
0
1
2
3
4
5
6
Chair quality index
7
Number of tables
50
8
EXCC
Optimal work
posture (%)
Minor deviations (%)
Major deviations (%)
EXCC
INCC All
EXCC INCC
All
EXCC INCC
82
10
40
65
8
21
38
12
5
25
42
12
Neck
87
Shoulder joint 3
Wrist
43
Back/spine
74
85
6
42
71
0
31
49
11
4
75*
19
13
18
59*
10
25
All
10
69
16
17
Classification is based on calculated index values (see description in Methods
section and Table 1). *denotes significant difference between external (EXCC) and
internal (INCC) call centres (po0.05).
INCC
40
30
20
10
0
Table 4
Prevalence (%) of work postures among call centre operators (n ¼ 156) classified
into ‘‘optimal’’ ( ¼ 100% of maximum index value), ‘‘minor deviations’’ ( ¼ 68–99%
of maximum index value) and ‘‘major deviations’’ ( ¼ 0–67% of maximum index
value)
1
2
3
4
5
Table quality index
6
7
Fig. 2. Distribution of quality index for chairs (values 0–8) and tables (values 0–7)
at the 156 workstations. High values indicate higher quality. EXCC, external; INCC,
internal call centres.
(80%) than during keyboard use (64%) (H21 ¼ 4:18, p ¼ 0.04). 54%
of the operators did not rest their hands and 37% did not rest all
fingers on the input device.
Most operators had an optimal back posture (Table 4 and 5).
Further, most operators (79%) rested their trunk either against the
backrest of the chair or (more seldom) against the front edge of
the desk.
Twenty-three percent of the operators reported that they were
dissatisfied with their work postures (Table 3). More EXCC
operators tended to be dissatisfied with their work posture than
INCC operators (28% vs. 13%,H22 ¼ 4:68, p ¼ 0.10).
4.4. Prevalence of pain
Pain in any of the studied body regions was reported by 77% of
the operators. Symptoms from the neck/scapulae were most
common (Table 6). No significant differences between EXCC and
INCC were found. Of those reporting pain in the shoulder joints/
upper arms or forearms/hands, 88% and 82%, respectively,
experienced pain in the dominant side.
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Table 5
Observed postures during computer work. Prevalence (number and %) of call centre operators with respective body posture at external and internal call centres
External
n ¼ 97–98
Neck extension–flexion (*)
Extension X51
Neutral: o51ext.;o151flex.
Flexion 15–301
Craned neck*
Shoulder joint extension/flexion
Extension X151
Neutral: o151ext.;o151flex.
Flexion 15–301
Flexion 4301
Shoulder joint abduction (*)
Neutral o151
15–301
4301
Shoulder joint rotation*
Inward X451
Neutral: in o451;outo151
Outward 15–301
Outward 4301
Wrist flexion/extension
Flexion X151
Neutral: o151ext.;o151flex.
Extension 15–301
Extension 4301
Wrist radial/ulnar deviation
Neutral: radial o101, ulnar o151
Ulnar deviation 15–301
Ulnar deviation 4301
Back extension/flexion
Extension X151
Neutral: o151ext.;o151flex.
Flexion X151
Back, lateral flexion
To the right
To the left
Internal
n ¼ 56–58
All
n ¼ 154–156
Number
%
Number
%
Number
%
12
84
2
4 (n ¼ 87)
12
86
2
5
2
55
1
10 (n ¼ 55)
3
95
2
18
14
139
3
14 (n ¼ 142)
9
89
2
10
1
50
30
17
1
51
31
17
0
34
17
7
0
59
29
12
1
84
47
24
0
54
30
15
24
56
18
24
57
18
25
24
9
43
41
16
49
80
27
31
51
17
1
62
31
3
1
64
32
3
2
42
13
0
3
74
23
0
3
104
44
3
2
67
29
2
2
64
28
4
2
65
29
4
0
33
21
3
0
58
37
5
2
97
49
7
1
63
32
4
62
34
1
64
35
1
44
13
0
77
23
0
106
47
1
69
30
1
12
79
7
12
81
7
4
50
3
7
88
5
16
129
10
10
83
7
0
12
0
12
1
10
2
18
1
22
0.6
14
Italics ¼ optimal work posture. Observations of neck position during looking at the screen or keyboard, observations of other positions during work with either mouse or
keyboard. *denotes significant difference between external and internal (po0.05; (*) tendency 0.05ppo0.10).
Table 6
Prevalence of pain (%) at least once a week during the last month in different body
regions among operators at external and internal call centres
Head
Neck /scapulae
Shoulder joints/upper arms
Elbows/forearms/wrists/hands/fingers
Back (thoracic/lumbar)
External
n ¼ 97–98
Internal
n ¼ 56–58
All
n ¼ 153–156
Number %
Number %
Number %
29
42
25
22
28
18
26
11
10
14
47
68
36
32
42
29.9
43.3
25.8
22.7
28.9
32.1
46.4
19.3
17.5
24.6
30.7
44.4
23.4
20.8
27.3
4.5. Associations between equipment, posture, satisfaction and pain
A high desk quality index was associated with better neck
posture (rho ¼ 0.20, p ¼ 0.02) and a lower frequency of back pain
(M–W p ¼ 0.05). Back pain was half as frequent among operators
with an easy-adjustable desk as among operators with desks,
which could not be adjusted or required tools for height
adjustment (21% vs. 42%; H21 ¼ 7:16, p ¼ 0.007). The desk quality
index was associated with the operators’ ratings of their desks
(rho ¼ 0.33, po0.001) and work postures (rho ¼ 0.25, p ¼ 0.003);
the higher the more satisfied. Furthermore, pain in the forearms/
hands was associated with the ratings of satisfaction with the
desk (M–W ¼ 0.18, p ¼ 0.035). Operators who had desks that
could not easily be adjusted for standing were seated more during
the workday (80%) than were those with more easily adjustable
desks (73%) (t ¼ 2.58 df ¼ 135, p ¼ 0.01). The proportion of seated
time during the workday was not associated with any musculoskeletal symptom, however.
Operators’ ratings of satisfaction with their chair and work
posture were associated with chair quality index—the higher the
quality index, the more satisfied (g ¼ 0.2, po0.001; g ¼ 0.23,
p ¼ 0.03, respectively). Furthermore, pain in the forearms/hands
was associated with the ratings of satisfaction with the chair
(M–W ¼ 0.19, p ¼ 0.02). Neck/scapular pain was more common
when armrests deviated X5 cm from optimal height (67% vs. 38%,
H21 ¼ 6:28, p ¼ 0.01).
Keyboards thicker than 3.0 cm were significantly associated
with dissatisfaction with the work posture; 37% of those with high
keyboards were dissatisfied compared with 16% with low keyboards (H22 ¼ 7:49, p ¼ 0.024). Neck/scapular pain was more
common among operators using a keyboard thicker than 3.0 cm
(56% vs. 38%, H21 ¼ 5:41, p ¼ 0.016). This association held true also
for back pain (39% vs. 22%, H21 ¼ 4:65, p ¼ 0.03). Pain in the
shoulder/upper arm region was associated with dissatisfaction
with the pointing device and its position on the desk-top
(M–W ¼ 0.18, p ¼ 0.035).
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A lower proportion of the operators were dissatisfied with their
display when the distance from desk front edge to the display was
within 50–70 cm (8.5%) compared with outside this range (17.0%)
(H22 ¼ 7:82, p ¼ 0.02). Neck extension X51 was observed among
22% of those with a positive viewing angle vs. 6% among those with
a horizontal or negative angle (H22 ¼ 5:44, p ¼ 0.07). Neck/scapular
pain was, unexpectedly, less frequent among those with positive
viewing angles (28% vs. 50%, H21 ¼ 3:83, p ¼ 0.05).
The ratings of satisfaction with work postures were not
significantly correlated to the observed postures. Symptoms were
also not significantly associated with the observed posture of the
relevant regional joint.
5. Discussion
In this sample of 16 Swedish CCs the qualities of the furniture
and ICT equipments were generally good and mostly fulfilled the
demands of the national law, European directives and ISO
standards. The main problem was how these furniture and
equipments were used, i.e. how they were positioned and
adjusted to fit the individual operator and to allow good and
flexible working postures. In fact, the majority of input devices
were non-optimally placed violating common recommendations
found, e.g. in international standards. Between 20% and 60% of the
furniture, VDUs and keyboards were non-optimally adjusted for
height. Mal-adjusted furniture and ICT equipment can cause
awkward postures in the neck, back and upper extremities.
Awkward postures were consequently frequently observed,
especially in the shoulder joints. Awkward postures can increase
the risk for health problems, e.g. neck/shoulder pain, if maintained for long periods without variation (Korhonen et al., 2003;
Marcus et al., 2002).
Exceptions from high quality furniture were, however, seen,
e.g. lack of easy height adjustability of many desks. Easy
adjustability of desk height is especially motivated where workstations are shared by different people, as is quite common in CCs.
This is also stressed by SWEA in its guiding instructions to the
provisions Work with display screen equipment (SWEA, 1998). The
results from the present study suggest that high quality of the
desk and keyboard and optimal adjustment of the chair may
contribute to less frequent neck/scapulae and back pain. This
study also showed that high standard of the desk, chair and
keyboard was associated with higher satisfaction among the
operators and that dissatisfaction with furniture and ICT equipments was associated with pain. Lack of comfort may thus be one
cause for symptoms among professional computer workers. An
opposite causal relation is also possible, however.
Sources for dissatisfaction may be that many tables could not
easily be adjusted for height and many chairs lacked, e.g. a tilt or
swivel function. Another contributing factor may be that many
operators lacked knowledge about how to adjust their furniture
and equipment for optimal work postures. This was shown in a
separate study of the state of knowledge among the operators, e.g.
how to adjust the height of their chair (Toomingas and Hansson
Risberg, 2007). The availability of adjustable equipment does not
automatically lead to better work postures if education in
ergonomics and how to handle the equipment is not provided
(Greene and Briggs, 1989).
A dose–response relationship, with odds ratios reaching 6–10,
was seen in the questionnaire-based study between an index of
comfort (Cronbach’s alfa ¼ 0.88) and both neck/scapular and arm/
hand symptoms, even after adjustment for potential confounders
like age, gender, exposure time and psychosocial factors (Norman
et al., 2008). Similar findings have been found in both crosssectional and prospective studies of pain among professional
1059
computer workers (Korhonen et al., 2003; Lassen et al., 2004;
Sillanpää et al., 2003).
Work at a seated position for many hours has been pointed out
as a risk factor for neck pain (Ariens et al., 2001; Juul-Kristensen
and Jensen, 2005). Varying body postures and alteration between
different surfaces to rest the forearms have been suggested as a
strategy to prevent musculoskeletal disorders (Delisle et al.,
2006). A workstation, including its office equipment and furniture,
designed to provide high variability of work postures is, therefore,
beneficial. The significant, although modest, association between
the possibility to adjust the desk and the higher daily standing
fraction in this study (indicating higher variability of position),
and that pain was less common in operators who had an easy
adjustable desk, may serve as an illustration of this. However, it
cannot be excluded that many of those who had back-pain were
equipped with an adjustable desk, as often is the case in Sweden.
This would have attenuated a true association between nonadjustable desks and back pain. The average seated time in this
study (75%) was slightly higher than that reported for office
workers with varying office tasks (70%) (Balogh et al., 2004).
Almost a third of the operators in this study could not easily shift
between seated and standing posture, because their desk lacked a
device for easy adjustment of height. There are obviously
possibilities for further improvements in this respect in CCs, like
in most computerized offices.
Awkward wrist postures during, e.g. mouse use, are associated
with an increased risk of arm/hand symptoms and signs according
to many studies (Marcus et al., 2002; Tittirononda et al., 1999),
even though studies with negative findings exist (Van den Heuvel
et al., 2003). Ulnar deviation 4201 which was common in the
current study may increase the prevalence of pain in the forearm
(Hunting et al., 1981). Our study did not show any association,
however. The deviating results may be due to uncontrolled risk
factors, such as force and repetition of hand/arm movements
(Tittirononda et al., 1999), or the short observation period.
Keyboard thickness 43 cm was associated with pain in the
neck/scapula region and the back. A thick keyboard (43.5 cm) has
been associated with a tendency for an increased risk of arm/hand
symptoms and signs as well (Marcus et al., 2002). A thick
keyboard, especially in combination with a too high desk may
cause shoulder elevation, abduction or flexion, and is associated
with neck/shoulder discomfort (Bergqvist et al., 1995). Shoulder
abduction is a well-known risk factor for neck/shoulder disorders
(Aaras et al., 1998; Cook et al., 2000).
The major deviations from optimal body posture were
observed in the shoulder joints, mainly abduction (68%), but also
flexion and outward rotation of the shoulder. These awkward
postures are characteristic of mouse-operating work (Karlqvist et
al., 1994) and are often caused by incorrect placement of the input
device on the table. A majority of the input device in the present
study were placed outside the optimal work area on the desk. This
dominance will cause a lack of exposure contrast, which may
explain the lack of significant association between the placement
of the input devices and pain. Mouse located outside the optimal
area of the desk has in other studies been shown to increase the
prevalence of symptoms in shoulder joints, elbows and wrists
(Karlqvist et al., 1996).
Productivity loss due to pain and other symptoms among
professional computer operators has recently been reported
(Hagberg et al., 2002; Hagberg et al., 2007). Such loss was
associated with among others non-optimal mouse position. Other
studies have found that performance at work may be negatively
affected by inadequate workstation adjustments and operators
discomfort (Ziefle, 2003).
Minor improvements and adjustments of the furniture and
equipment at the studied workstations would have doubled the
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proportion of operators who had good wrist postures (from 42% to
approx. 84%, Table 4). Improvements would involve adjusting the
keyboard from positive angle to 01 or negative angle, placing the
pointing device within shoulders width and forearms reach and/
or changing to a thinner and narrower keyboard. Such changes in
the placement and design of input devices may have improved the
suboptimal positions of the shoulder joint as well.
Musculoskeletal discomfort at CC work can decrease with
forearm support (Cook and Burgess-Limerick, 2004). However,
even if most workstations had possibilities for forearm and wrist
rest, this was not used by many of the operators. Again, this
supports our observations of inadequate knowledge in good
computer working techniques among the operators. Measures to
obtain such support are usually quite simple. The keyboard should
not be positioned too close to the front edge of the table, as that
has been associated with risk of neck/shoulder symptoms and
signs (Korhonen et al., 2003; Marcus et al., 2002). Armrests on the
chair or supporting the forearms on the table top can reduce the
risk of neck/shoulder (but not arm/hand) disorders (Aaras et al.,
1998; Aaras et al., 2001; Jensen, 2003; Kryger et al., 2003; Lassen
et al., 2004; Marcus et al.,2002). Further, variability in forearm
support is suggested to decrease musculoskeletal disorders
(Delisle et al., 2006). A good working posture can only be enabled
if all parts of the office equipment (furniture, input devices and
display) are well designed and fit together to form an integrated,
functional and comfortable workstation unit.
The ergonomics/design of the workstations and the qualities of
the equipment generally had higher standards and the adjustments were more optimal at INCC than at EXCC, reflected in
higher ratings of satisfaction. The work postures were slightly, but
not significantly, better at INCC compared to EXCC. The frequency
of symptoms was the same, however. Freestanding EXCCs provide
customer services to other client companies who have decided to
outsource their customer service contacts. EXCCs make business
of this phenomenon but have to compete for clients with other
EXCCs on an open market. Costs are quite often the most
important issue in this hard competition. This may have reduced
the resources in time and money for a focus on work-environment
issues. INCCs provide services to the customers of the mother
company adding value to its products or services. One of the
reasons for not outsourcing the customer service to an EXCC
might be that the company is keen on the quality of the customer
services and wants to keep a closer control over it, making sure
that all involved share the same identity, values and norms. This
might lead to an emphasis on the quality aspects, not only on the
customer contacts, but also on the working conditions, both
physical and psychosocial. These differences between EXCC and
INCC may lead to differences in investments in high quality
furniture and office equipment and in training of the staff in
adjustments and proper work techniques.
To our knowledge there are only few reports available on the
influence of company organization on equipment and design of
workstations. The physical working conditions at the INCCs in this
study were also found to be somewhat better than at the EXCCs,
e.g. more space, better cleaning routines, better vision ergonomics
and lower noise levels (Gavhed and Toomingas, 2007). Other
differences between the EXCCs and INCCs have been reported
mainly regarding the contents and quantity of work, time spent on
further training, call-logging and monitoring (Norman et al., 2008).
have declined to participate in the study. This unwanted selection
of study objects may have caused an underestimation of existing
work environmental problems at Swedish CCs and subsequently
have reduced the power to discover possible true associations
between exposure and outcome.
Since this study was part of a larger study, which was designed
to survey many working conditions at the CCs (organization,
psychosocial and physical conditions, workstation design, educational level in ergonomics, work postures and medical problems,
etc.), most variables were given a short attention. Possible nonrepresentativeness would have attenuated true associations
between exposures and outcomes.
Some factors may have concealed possible associations
between symptoms and work posture and placement of equipment in this study. Firstly, the operators may have worked at
different workstations during different workdays or periods.
However, the equipment within a CC is often uniform and may
not have diverged very much. Secondly, a good individual work
technique may compensate for some of the negative effects of
maladjusted furniture and equipments. Finally, other risk factors
may have confounded, like the psychosocial conditions.
It is well known that a cross-sectional study like this cannot
secure causal relationships between symptoms and exposure why
a prospective study would be needed. There are many practical
problems related to such studies in the CC business however, e.g.
high company and employee turnover rates.
6. Conclusions
Modern computer workstations at CCs are in many respects of
a high quality, but do not always follow the National Work
Environment Law, the EU-directives or the recommendations
given in international standards. This is even in a country like
Sweden with a traditionally high awareness of safe work and
health issues. The main problem is, besides some deficiencies in
the design, how furniture and ICT-equipments are used, i.e. how
they are positioned and adjusted to fit the individual operator to
allow good and flexible work postures. This may be explained by
lack of knowledge and abilities how to do and/or a lack of
understanding of its relevance. Optimizing basic adjustments
would improve conditions substantially in many cases. There is
thus a potential for cost-effective improvements in the conditions
for CC work with possibilities for a gain in comfort, health and
productivity.
Acknowledgements
We thank Eva Hansson Risberg, Anita Isaksson and Kerstin
Norman for their extensive work with data collection at the call
centres, Ewa Wigaeus Tornqvist and Anders Kjellberg for advice
during the planning stages of the study, and Maud Hagman and
Björn Sköldström for data management, statistics and other
valuable assistance. We also thank the participating call centre
companies and their employees who agreed to take part in this
study. The study was financed by the Swedish Council for Working
Life and Social Research.
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