Computer use in cold environments

Computer use in cold environments

Applied Ergonomics 31 (2000) 239}245 Computer use in cold environments Anna-Christina Blomkvist!,*,1, Gunvor Gard" !Department of Human Work Science,...

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Applied Ergonomics 31 (2000) 239}245

Computer use in cold environments Anna-Christina Blomkvist!,*,1, Gunvor Gard" !Department of Human Work Science, Division of Industrial Ergonomics, University of Lulea> , Sweden "Department of Muscolosceletal Disorders, Division of Physical Therapy, Lund University, Sweden Received 9 June 1997; accepted 11 October 1999

Abstract This study addresses computer work in cold environments with the two-fold aim to explore conditions for such work, and to add knowledge about the use of "ngers at data entry in the cold. Five workplaces were visited and work contents and use of computers are brie#y described. E!ects of work in the cold were in line with those mentioned in the literature, and manual lifting of heavy goods the most impairing activity. Subjects contended with strenuous working postures * holding the computers in their hands or arms * and with cold "ngers. Individual "ngering for data input was noted. Fore"nger or a pen were used, and a pen is recommendable for input, either as a touch pen or, simply to press the keys. A supportive rack could be recommended for portable workstations. ( 2000 Elsevier Science Ltd. All rights reserved.

1. Introduction Many people work in the cold, either in cold store rooms or in cold weather. Table 1 shows to what extent Swedish workers were exposed to cold from 1989 to 1993, and that workers quit with age; women sooner than men (Andersson, 1997). De"nitions of what is meant by cold work and other standard issues are seen in Vogt (1998). It is strenuous to work in the cold. Cold negatively e!ects manual (Clark, 1961; Enander, 1984) and cognitive performance (Baddley et al., 1975). Skin problems (HalkierS+rensen and Thesterup-Pedersen, 1994), lower back and knee pain (Chen et al., 1991) and psychosomatic problems (Griefahn et al., 1995) occur, and work in cold areas often coincides with other strains, such as lifting heavy things, noise, etc. (HolmeH r, 1996). Cold "ngers and hands limit work in cold areas (HolmeH r, 1995), and cooling of the forearm and the hand is detrimental to manual dexterity performance (Giesbrecht and Bristow, 1992). Some people work in the cold using computers. One aim of the present study was to explore the conditions for the use of computers in the cold, and make them known.

* Correspondence address. TurbingraK nd 12, S-176 75 JaK rfaK lla, Sweden. Tel.: #46-44-20-30-00; fax: #46-44-20-32-03. E-mail address: [email protected] (A.C. Blomkvist) 1 Now at Department of Behavioral Sciences at Kristianstad University, 29188 Kristianstad, Sweden.

Another aim was to learn how workers managed computer interaction, including "ngering, and to obtain comments on use of current equipment. Five workplaces are presented here, where employees used computers to various degrees during or after exposure to cold. Trade unions recommend warmed cubicles for computers and their operators. Some computer jobs have to be performed in the cold, however. Also, when people have access to heated premises, it takes time to get warm after a work period in the cold. Ordinary desktop computers, portable computers and specially designed hand-held computers are in use. Desktop computers in cubicles or o$ce rooms are suitable when workers can postpone data input. Portable computers and hand-held computers are for jobs where data input must be performed directly. The main technical problem is loss of battery power in the cold. Technical bene"ts are the simplicity with which information can be sent to them, or read back and forth to the desktop. In Figs. 1a and b,2 two recent portable computers are shown. Both examples utilise GSM, the Global Positioning System. GSM makes computers more useful in the outdoors. In combination with the general increase in IT, GSM may make computer use in cold environments more common in the future.

2 from Panorama 1996 No2 Courtesy Cap Gemini Group, Stockholm.

0003-6870/00/$ - see front matter ( 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 0 3 - 6 8 7 0 ( 9 9 ) 0 0 0 5 7 - 5

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Table 1 Percent of the Swedish workforce within three age ranges working in the cold for at least one-fourth of their working time! Age

Men

Women

16}29 30}49 50}64

27 23 20

13 8 4

!The de"nition of &cold' varies with the premises. Women drop out earlier than men. Data from Andersson (1997).

Fig. 1. (a) to the left, a small hand-held computer is screwed on to an antenna, which also is a stick. The equipment was tested for mapping by the police authorities in Stockholm in 1995; (b) above, the user carries the computer prototype on his left forearm, and the antenna is attached to his knapsack.

observations covered muscular activities, joint positions, etc., and the judgements were of the kind now recommended by the Swedish National Board of Occupational Safety and Health (AFS, 1998) as a result of a joint Scandinavian development project supported by the Nordic Council of Ministers (see also Kuorinka et al., 1987). The questionnaire was formulated in accordance with routines tested at a wide range of work places, and for which reference data are available (Ydreborg and Kraftling, 1988; Ydreborg and SandstroK m, 1988). Our selection covered physical activities (walking, climbing stairs, bending, reaching, working above shoulder height, etc.), pain in joints and main parts of the body, and clothing. Some items covered cognitive demands (high work pace, even pace, concentration, #exibility, etc.) A few assumed problems were added (slowness, numbness, etc.). The questionnaire ended with items on stress and mood, as recent studies indicate that feeling cold causes a low mood (Orden and Benoit, 1996; Anderson et al., 1996). The response scales used the frequency estimates: often, sometimes and not at all, later coded 2, 1 and 0. Questions about which "ngers were used, and which "ngers ached or felt cold were all illustrated with pictures of the right and left hand showing the palm and the back of the hand * on which the subjects were asked to check and circle to indicate `oftena and `sometimesa, respectively. Details on "ngers were not covered by the traditional questionnaires and we had no experience of how well "ngers were known by their names (fore"nger, ring "nger, etc.). The questionnaire was distributed to those who were present at the work sites at the time of our visits. The workplaces were entered as dummy variables in the data matrix. Items in the questionnaire correlating with the dummies so that p(0.05 are reported as characteristic for the workplace in question (and here account for more than 15% of the variation between the workplaces). Other variables mentioned in the workplace descriptions account for at least 7% of the variation.

2. Method

3. Results

With the assistance of the Swedish trade unions, the workplaces selected and visited were a cold store, a Swedish Telecom department for prospect planning, and a shunting yard of the Swedish State railways * all in Northern Sweden*; a timber yard in Central Sweden; and a cold store in South Sweden. The visits were made in 1996. A schedule for observations and a questionnaire were prepared in advance. The observations were made by a trained physiologist and served as a subject for conversation at the same time as they were written down. The

The workplaces are presented one by one, to give an idea of the work content, together with a selection of local answers to the questionnaire from each place. Then follows a general summary of the results from the questionnaire and an overview of the "ngering used for data entry. 3.1. Example 1: stock room work in Northern Sweden This store served the most northerly 30 000 km2 of Sweden. The temperature was between 4 and 83C in the

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cold store room, and !25 to !303C in the freezer storage. A computer room adjoining the cold store room kept about 163C, and a well-insuolated computer room connected next to the freezer storage about 203C. All employees did piecework. In the storage area they gathered products into containers from print-outs, and then went to the computer room and keyed in data of their completed orders in batches. There were spontaneous complaints about back pain, but not about data input. They experienced clumsiness and a lowered sensitivity to pressure for the "rst "ve minutes, but after 10}15 min in the computer room, body and hand temperatures seemed normal. Five persons answered the questionnaire. Characteristics were: same low temperature all year around, no draft, no dampness, low preferred temperature at work, and possibility of wrist support for data input. With 16 years of average employment time these workers formed the most loyal group presented here. Their work included manual lifting of heavy goods and work at shoulder height, and they perceived their work as being physically demanding. They had shoulder pain, and complained about the length of the number sequences identifying customers and articles.

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cars, in which the planners could work now and then. Calculations and plans were completed at the o$ce. The portables were too heavy; 1.5 kg is heavy after a while, we were told. Standing outdoors caused muscle strains in the shoulders, the elbow #exor, and hand extensors, along with considerable static load. Sometimes an extended little "nger stabilised the distance between the touch screen and the pen. The outdoor light lowered the display contrast and caused viewing di$culties, and the display faded even more after a while in the cold, due to capacity loss in the batteries, and the characters displayed on the screen were small. The slower the data input, the longer the workers had to stay out in the cold, and the higher the risk was that the batteries would be exhausted. Four planners answered the questionnaire. Characteristics were: psychic strain, demands for creativity and management of new tasks, age (mean age "51), and di$culties with reading from the display. They felt that concentration di$culties were their main problem outdoors, but they did actually work with a complex user interface. Other problems were lack of "ngertip sensitivity and slowness. 3.3. Example 3: train checking in Northern Sweden

3.2. Example 2: prospect planning in Northern Sweden The planners were exposed to cold in winter when working outdoors, see Fig. 2. Their outdoor task was to add observations of telecom systems and ground conditions to databases. They used portable computers with the same menu- and window-based software as those used indoors, and parts of the same databases. For taking bearings the portable computers were either adapted to GSM or picked up pulses from the mileometers in the

Every goods wagon has a unique number and a country code. The checkers (wagon inspectors) noted wagon number, order in the train, any damage, outcome of brake test, etc. The computer display showed menu items or presumed wagon number * one at a time * loaded down from a central system. Each outdoor checking spell lasted about half an hour, and was completed indoors on desktops. A hand-held computer where the checker enters data with his thumbs is seen in Fig. 3. It is a thin

Fig. 2. A prospect planner standing in the snow working with a pen on a touch screen over which he is bending in order to get the appropriate viewing distance and to shade the screen.

Fig. 3. Hand-held computer. This train checker holds the computer in both hands, and presses the keys with his thumbs. Using the computer this way distributes the load to both arms, and facilitates reading from the display for comparison with the numbers on the wagon sides.

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computer, not easily balanced on the forearm, but when this was managed, keys were pressed with a pen. We were told that there were gloves where the tips of the "ngers could be turned up. Input was slower when checkers got cold hands, and they thought they made more errors then. The batteries had to be charged more frequently in winter. Two train checkers were available for the questionnaire. They had experienced the lowest temperature of all workers in the study, !363C, and reported characteristics were dampness and draughts causing clumsiness and slow work. In all, they spent much time outdoors, and felt the after-e!ect of carrying the computers.

Scalers used a #at computer with 30 keys (20 function keys) and a 5-row display. They mentioned, as did the train checkers, that the keys could be pressed with a pen or a pointed object. The timber-yard was located at the Gulf of Bothnia, and the onshore wind is damp. The "ve persons answering the questionnaire were the only workers in the present survey who complained about snow on the display. Characteristics included tall and heavy personnel !183 cm and weight 96 kg on average * and large temperature variations, draughts, dampness, and hand pain. They used thin gloves in order to manage gauging and data entry, and reported "ngertip numbness.

3.4. Example 4: Appraisal of arriving timber

3.5. Example 5: stock room work in South Sweden

Most timber arrived at the timber-yard on trucks with two or three trailers. The timber was assessed by stationary personnel immediately on arrival. There was a second check after unloading and "nally random samples were evaluated by other timber scalers to ensure impartiality. The latter scalers were employed by an association of forest owners along with the sawmilling, pulp and paper industry. The "rst assessment included volume, knot, and rot of the timber. It was done from above a bridge at the gate to the timber-yard, where the trailers could be inspected. The timber scalers took notes and then ran down to a hut to enter the data into a joint computer system, common for Swedish forestry, while the truck drivers waited impatiently. The computer screen was placed high up in order to facilitate the drivers' check of the results. The second and third, more elaborate evaluations were completed outdoors, generally by two or three scalers, one of whom handled the computer. The computer was either held on one arm, or carried in a harness, see Fig. 4.

The cold area was kept at a temperature around 83C and the freezer area at around !283C. Forklift trucks were used for vertical and horizontal movement of goods. In the trucks there were computers as small as mobile telephones with a set of 16 keys and a display. Orders were transmitted to the computers, and when all went well, the truck drivers con"rmed the lots picked one at a time by pressing one key. There were no complaints about this technical arrangement. Other tasks were similar to those in the northern storage described above. Job rotation was practised. Eight workers took the time to "ll in the questionnaire. Characteristics were low age, heavy lifting, and large arm movements, as well as a demanding work pace. (Forwarding agents complained about back pain because of heavy goods. Truck driving caused neck and shoulder pains from looking upwards when driving.) They felt that they were required to be alert and creative, but they also claimed to learn nothing new on their jobs. 3.6. General summary of responses to the questionnaire In all, 24 workers answered the questionnaire. The most frequent answers to the general items are presented "rst, followed by answers to questions on data entry, and correlation between answers. The summary should be read with the descriptions of the workplaces in mind. Codes 2 and 1 are counted together when frequency of occurrence is reported. 3.7. General items

Fig. 4. (Above) the empty harness; (Below) the harness supporting the computer and also serving as a wrist rest. The display is o!.

All respondents checked walking and standing under physical activities, and accuracy, watchfulness, and promptness under mental activities. Twenty two subjects checked each of the variables manual lifting, work above elbow height, physically and mentally demanding work, and demand for creativity. The workers were exposed not only to cold but to temperature variations from !30 to #303C. 50 percent of them were exposed to dampness,

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and 75% to draughts. Pain in neck and shoulders and lower back was reported by 70%. Corresponding percentages of neck problems were for woodmen/ packers/truckdrivers 25/40/31 percent, respectively and for lower back problems 21/89/25 percent (Ydreborg and Kraftling, 1988; Ydreborg and SandstroK m, 1988). 80 percent of the respondents stated that they had experienced some problem caused by the cold during the last 12 months. This percentage is close to the percentage among Swedish truck drivers (Ydreborg and Kraftling, 1988). Nearly 50% reported that the cold alone had caused them (painful) inconvenience, and 25% felt discomfort every day after working hours. 20% said they were sensitive to cold, which is probably a normal ratio. Wrist protection was uncommon, but thick or thin gloves were used. 62 percent of the workers removed their protective clothing for indoor work periods at the VDUs. Fitness training was practiced by 50 percent, and 25% were smokers. The "rst number is a bit high for Swedish workers, but the number of smokers is normal. They suggested a temperature of about 153C as being ideal for the work they performed. 3.8. Data entry As can be understood from these examples, data entry was performed under two conditions by some employees: workers using computers in the cold also used computers in o$ce temperatures. At the railway site and the telecom company, indoor desktop VDU workplace layout was good. The employees' postures were relaxed and they could rest their forearms. These companies had a vast knowledge of VDU workstations for o$ces. As a contrast, the storage room workers and the timber scalers worked with their arms unsupported, and the VDUs were placed on tables which were too shallow to provide a comfortable arrangement. The computers for outdoor use were designed for the speci"c tasks, and di!ered from each other. User styles di!ered even more. Complexity of data for input, the need to read more * or less * data on the display, and length of work periods in the outdoors were in#uential factors for choice of equipment and user style. Other factors were probably body size, muscular strength, faculty of vision, and tendency to feel cold. The only recurrent comment on data input in the outdoors was the suggestion of using a pen instead of "ngers. Another observation was that with a rack, the left hand was often &hung' under the rack while the right hand was active. When no rack was used, the left elbow was kept in a locked position as in Fig. 1b. In the questionnaire we asked about e!ects of cold on data input without discriminating between outdoor or indoor work. As seen in Table 2 the respondents thought that cold resulted in slower input. The second most frequent complaint about data entry in the cold was

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Table 2 Mean values of responses to di$culties at data entry on a scale from 0 to 2, and number of responses higher than 0; n"24 Di$culty/Item

Mean

No. of responses '0

Reading Viewing Memorising data for input Memorising input completed Concentration Temper Finger insensitivity Clumsiness Slowness

0.2 0.1 0.1 0.1 0.4 0.4 0.3 0.8 1.1

3 1 3 2 8 8 7 12 17

Has wrist support Has elbow support No. of "ngers used for input Arm position uncomfortable

0.1 0.1 3.2 2.0

3 2 * 20

clumsiness. Then came statements on di$culties with concentration and temperament or mood. Only two persons had use of wrist support. Few other complaints, such as problems with memorising or reading, were reported. The respondents were asked to mark on drawings which "ngers they used for input, and how frequently. Mean number of "ngers used was three as seen in Table 2, but the type value was two "ngers. Only one person used all ten "ngers, and "ve persons used one "nger. Strategies for "nger use are seen in Table 3. Among persons using identical equipment, use of "ngers varied, as did the tendency to feel more cold in one "nger than another. Ten out of 13 managed to use at least one "nger that did not have to be avoided because of sensitivity, and 10 out of 13 persons avoiding any "nger at all (see Table 3) did work using the fore"nger. 3.9. Covariations Many items correlate with other items within the same group; pain in one shoulder goes with pain in the neck and the other shoulder, etc. These covariations are less interesting than correlation coe$cients across groups of items. As stated above, the timber measurers were taller and heavier than the other workers, and the personnel at the distribution centre were younger than the other groups. Such di!erences between workplaces make comparisons biased, and correlation coe$cients across groups of items should be interpreted with caution. However, some relations are mentioned here because they are intelligible, in line with general experiences, and because they, along with other research could generate hypotheses on consequences of cold. Relations mentioned below were at least signi"cant at the 5% level.

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Table 3 Fingers used and avoided at data entry when user is cold; n"23 Subject!

Fingers used for data entry

Fingers avoided in cold

S1 S2 S3 S5

All "ngers on right hand Right fore"nger All "ngers but the thumbs All right hand "ngers but little "nger Fore-, ring-"nger Right fore-, middle "nger All "ngers, thumbs least Right thumb, middle "nger Right fore"nger, thumb sometimes Right fore"nger, then middle "nger, least thumb Middle "ngers Right fore"nger, middle "nger somewhat Right fore-, middle "nger, no thumbs Right fore"nger, then middle "nger Right fore"nger, then thumb, middle "nger Right middle "nger Right fore"nger Right fore"nger Preferably right fore"ngers, but all f.s somewhat Middle "ngers Right thumb, fore-, middle "ngers Right fore"nger Right fore"nger, middle "nger somewhat

Right middle "nger * Fore"ngers All but thumb

Te6 Te7 Te8 Te9 R10 R11 Ti12 Ti13 Ti14 Ti15 Ti16 D17 D18 D19 D20 D21 D22 D23 D24

All but thumbs * All but thumbs All "ngers, hand outside * Ring-, little "nger, thumb Ring-, little "ngers Ring-, little "nger Middle, Ring-"nger Fore-, ring-"nger * Thumbs, little "ngers All "ngertips * *

restricted performance. Mental strain correlated with keeping even pace, concentration demands, feeling cold, and long number sequences for input. Using few "ngers for data entry did not correlate with workplace, but did however correlate with working outdoors, lower back pain, and restricted performance caused by the cold. Thus it is clear that climate and work posture, including how the hand-held computers are carried, restrict the number of "ngers used. 3.10. Workers' written comments As usual the workers praised the spirit of comradeship, but two of them noted that they seldom met their supervisors. This could be compared to similar remarks from the o$ce area: when computerised work#ow is introduced, there is less need for supervisors to intervene (Blomkvist and OG stberg, 1994). One cold worker remarked that the salary seemed sized after the heat. One teleworker feared that a future more complex interface would lead to smaller characters on a more crowded display, increasing the problem with low contrast in outdoor daylight. The scalers emphasised the choice of insulating material for tools to be used in the cold, and one of them suggested a rack which could easily be lifted on and o!, as in Fig. 5. The cars were ill adapted

* * * *

!S"Stock room, Te"tele, R"railway, Ti"timber, D"distribution centre workers. S4 forgot to answer. Most frequently used "ngers are mentioned "rst for each person. Subjects D19 to D24 explicitly said they did not feel cold enough to avoid any "ngers.

Four women were included in the study. They reported signi"cantly more physical injury from cold than the men. However, the women did not feel colder than the men, and did not report more mental strain. Six workers were smokers and four used snu! (with an overlap of two). Three drank beer with lunch. Smoking correlated with viewing and reading di$culties, and snu! also with concentration, memorising, and temper di$culties. Those who drank bear reported being fumbling and slow. Manual lifting was the only factor in the present material which could explain injuries caused at work. Physical strain correlated with lifting and large arm movements in the cold, including work above the shoulders, little sitting, and little variation of the work. With more variability there were fewer injuries resulting in

Fig. 5. A rack, as outlined, was suggested. A headset and a receiver were added here. A hanging rack can easily be lifted o! outdoors. It should leave pockets free. Note that the wrist rest should be at an angel to the body * as should the computer support * in order to o!er correct positioning of the right hand during data entry. The angled support is drawn in a thick black line.

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to computer work, the project planners added. The truck drivers preferred steering-wheels `so small you can steer them with one "ngera, which indicates problems with cold as well as with baggy clothing. One train checker said that she carried the computer in her armpit to warm it up.

4. Summary of results Temperatures varied between the places visited, as did working conditions. Yet, the general impression conveyed to us was that computers were appreciated by the employees. Manual lifting of heavy goods seemed to be the main drawback. Thus, the complaints listed were in line with those in the literature, and computer users in cold environments are in the same situation as other workers in the cold. The main particular problems with computer use in the cold were exhausted batteries, impaired display contrast by ambient daylight, too heavy computers, strenuous working posture } and cold "ngers. Data input was slower in the cold. Other interfering e!ects were clumsiness, concentration di$culties, and bad temper. Hand grip and arm position varied. A wide individual variation was seen in number of "ngers used and which "ngers felt cold. The fore"nger was often used; even when workers felt cold. Some workers recommended that key input be done with a pen. It is reasonable to recommend picking with a pen after having learned how few "ngers workers use for data input.

5. Conclusion Computers can and will be used in cold areas. They o!er access to valuable information and data from observations can be entered alternately with error checking and storage. Working posture can be improved with lighter computers and appropriate support for hands and arms. Demand for su$cient display size and contrast set limits to the size and thus to the wants of lighter computers. A wrist support for the hand used for input stabilises the distance between the hand and the surface to touch. Also the hand not used for input needs relief and support. A summary of comments is seen in Fig. 5. A sling should be easy to take o! and easy to adjust. A di!erent solution could be a light computer resembling a mobile telephone, which would su$ce for registration of wagons and quality judgements. The fact that few "ngers, generally fore"nger or middle "nger, are used for data input should be considered at development. Instead of "ngers, a pen can be used, and pen as a "nger substi-

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tute has a longer reach. Also, demand for concentration because of long series of numerical data should be avoided in the interaction with the computers.

Acknowledgements This work was made possible by a grant from the Swedish Council for Work Life Research (Project 940098) with A.-C. Blomkvist as project leader.

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