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Work under extreme conditions H. LUCZAK



Institut für Arbeitswissenschaft , Strasse des 17 Juni 135, Berlin, D1000, Germany Published online: 06 Jul 2010.

To cite this article: H. LUCZAK (1991) Work under extreme conditions, Ergonomics, 34:6, 687-720, DOI: 10.1080/00140139108967346 To link to this article:

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199 1, VOL. 34, NO. 6,687-720

Work under extreme conditions Institut fur Arbeitswissenschaft, Strasse des 17 Juni 135, Dl000 Berlin, Germany

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Keywords: Workload; Climate; Acceleration; Pressure Operator-behaviour; Air traffic control; Examinations; Shiphandling.

Extreme conditions are defined in tenns of deviation from the norm, and the mismatch between capacity and demand. Analysis of ergonomic job description data revealed the predominance, through their frequent occurrence, of extreme conditions. Extreme work environment conditions, such as climate, acceleration, and air pressure, are discussed. Task and error-concepts for workers operating under extreme workload are investigated, with reference to Chernobyl, stressstrain concepts for ATC, college examinations and shiphandling.

1. Introduction Any survey of 'work under extreme conditions' is an 'extreme' task in itself;

'extremely' wide, because nobody can delineate all extremes, 'extremely' specific because any extreme has to be considered in ergonomic terms with respect to its cause and effect. Thus any evaluation requires 'extreme' expertise. This relationship between breadth and depth creates a dilemma for the author. He or she either has to give up expert status in order to cover all extremes, or has to restrict the report to themes which lie within the span of his or her scientific area of expertise. In order to decide which problem areas can be taken into account, it is necessary to define what 'work under extreme conditions' means. The most simple definition would be not 'normal' stressor conditions! In terms of statistical probability or frequency distribution, 'extremes' can be defined as deviations from a mean value, let us say 1, 2, 3 a, or percentiles, or relative ranges. Such a definition of extreme load requires meaningful variables in ergonomic terms, in order to facilitate a quantitative or qualitative approach to the scale over which the probability or frequency distribution can be formulated. Empirical data on possible ranges of extremes of individual strain can be found in fuzzy sets of weight perception (Luczak and Ge 1989) where a relatively homogeneous collective of male students classified their .perception of weight in a lifting task according to possibility values, which were then processed into possibility functions (see figure 1). The extremes 'very light' and 'very heavy' obviously have considerable ranges,. e.g. 0-22 kg for the lower extreme, 12-62 kg for the upper; and an overlap of possibility functions between the upper and lower extremes is found. Thus an absolute identification of extremes seems to be doubtful, because 'normal' and 'extreme' cannot be distinguished 'clearly. Approaches with relative identification procedures have to be adopted. The basic purpose of ergonomic design is to adapt and match: to adapt work demands to human capabilities; to adapt human performance to work demands.

This simple and well known philosophy, first formulated in Protagoras' dictum that 0014-0139/91

$3-00$) 1991 Taylor & Francis Ltd.

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Figure 1 . Ciassification of weights Iihed into rncmbership values of individual strain perception (Luczak and Ge 1 989).

Figure 2. Classification of 'extreme' working conditions.

'man is the measure of things', can be used to derive a second model for extremes: an extreme can be defined as a substantial deviation from an optimal situation of adaptation or match of capability and demand. This definition leads to a model of underload and overload (figure 2). Given the progressive automation of human functions in work systems, problems of underload undoubtedly have received increased attention in ergonomics. Nevertheless, problems of overIoad have a longer history, and therefore a better scientific background in the subject; I shaIl therefore restrict the further discussion to overload aspects. Another approach for the identification of what work under extreme conditions may mean, consists of introducing task-specific and environmental scales of load. Taking the theme of work under extreme conditions seriously on a semantic level, the term should be understood as indicating a normal workload with extreme environmental factors. Another semantically tolerable interpretation might be a human under extreme work stressors; in other words, normal environmental factors with an extreme task workload. To combine both arguments, the super-imposition of

Work under extreme conditions


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environmental and task-specific loads with respect to a human reaction under this load has to be considered. A further simple concept for defining work under extreme conditions can be introduced by describing a sphere concerned with an objective (or object-oriented) analysis of work on one hand, and a second sphere, concerned with a subjective (or subject-oriented) analysis of work. In the first case, extreme conditions are diagnosed by means of task or job analysis techniques through seldomly occumng scorings in scales, which represent an expert's view of technological and organizational extremes, or-in workload models-objectively describe a situation near the limits of human capabilities, e.g., in biomechanical or informational terms. Subjective analysis, on the other hand, enquires about individual reactions of a single working person or the social reactions of a worker's group: these reactions can be quantified in different scales, for instance in physiological terms as reactions of organic systems, in behavioural terms as performance or failure measurement, or in psychophysical terms as reception, classification, and evaluation of work-related stimuli (figure 3). objective




analysis of work

analysis of work

technologicel and

reaction of a working

organizatlanai facts

person in an actual

of w M n g condlths

working situation

Figure 3. Differentiation of approaches to identify 'work under extreme conditions'.


In the relation between objective and subjective identification of extremes, a problem interferes, which can be made clear by the following example. In an oriental bazaar I saw craftsmen sitting on their heels from dawn to dusk punching holes in pieces of leather, a situation which a European ergonomist would classify as intolerable, because of the posture and the corresponding one-sided muscular workload. Asked whether they had any complaints about their working conditions, the craftsmen laughed and answered that there is nothing to complain about, and that their families had been doing the same work in the same way for generations. A young man once turned the question back on me, the European, and asked whether all this thinking about work-related problems didn't cause headaches, and whether the unsolved problems would not cause melancholia or depression. The conclusion to be drawn from these anecdotes is quite simple: what is 'extreme' for me is 'normal' for you. What is what, depends on the sociocultural context, the biography, the qualification, the bodily and mental circumstances, and so on (figure 4).

2. Frequency/importance of selected extremes An object-oriented (objective) first approach to the question of the importance and localization of extreme conditions, is to ask experts with which tasks and jobs they

H. Luczak

constant within a life cycle

variable, but not changeable

P= -

changeable fw the short term by interventions





Physical Type




Ethnical Type

Health Status





Hereditary Factors

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changeable by long-lasting



v Characteristics of Disposition


of Qualification


of Adaptation

Figure 4. Individual characteristics of matching 'conditions' and 'persons'.

classify work as taking place under extreme conditions. In 1975 an ergonomic job analysis technique was developed (Landau et al. 1 97 5), which even tua1ly became the AET-Arbeitswissenschaftliches Erhebungsverfahren zur Tatigkeitsanalyse (Rohmert and Landau 1979). To date, this method has been applied to 3683 work systems by a group of experts with a high inter-rater-reliability. Each work system is entered into a data bank by means of 2 16 items in (mostly five-step) ordinal scales of frequency, importance, workload, and time. It therefore seems worthwhile to look into this data set in order to determine what kinds of jobs are evaluated by the experts as being connected with obvious extremes like toxic materials, confinement, physical and chemical environments with high levels of stress, high risks, and heavy responsibilities for lives and materials. (The author gratefuIly acknowledges the help of Prof. Landau in the statistical processing of this data, and the generous consent to use the content of the data bank held by Profs Landau and Rohmert.) The data bank is not a perfect representative sample of work systems in Germany. Its content may be biased with respect to specific design deficits and ergonomic problems. .Nevertheless, it covers jobs from all sectors of industry and administration in Germany, and the data bank forms a valuable and broad documentation of working conditions (Landau 1984). 5.65% of the data bank entries are reIated to extremely dangerous materials, like explosive, flammable, poisonous, caustic, or radioactive substances. These include work systems of washing, drying, and cleaning with chemicals, production of these substances and with these substances, laboratory work, soldering, melting, polishing, and surface finishing. This is the classic domain of occupational toxicology and medicine. Extreme confinement is a characteristic of 7.2% positions, mostly cockpit work in different vehicles, administrative and civil service jobs in constricted offices, control room work, kitchen work and, last but not least, mining and assembly in their respective environments. Workplace design in anthropometric terms betrays extreme deficiencies in this area. The physical environment, namely illumination, climate, mechanical vibration, noise, and atmospheric conditions, which even partially require protective

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Work under extreme conditions


measurements, are classified as extreme in almost 40% of all jobs registered in the data bank (1450 out of 3683). The presence of noise in any production and transportation job contributes considerably to this astonishing result. Most jobs stem from branches of the manufacturing and building industries: only very few administrative jobs can be found in this sample. 'Extreme' physical environments seem to be quite frequent in the industrial sector. Another extreme might occur where the probability of occupational disease is high, andlor where the risk of injury is high. This sort of extreme is found in almost 20% of the jobs (723 out of 3683). Accordingly, occupational safety and health measures demand more comprehensive implementation, especially in basic and process industries, and in the production of manufactured goods. Many jobs contain responsibilities for people. and goods: the consequences of the working person's actions rated as probabilities and estimated extent of loss and damage can be constructed as creating 'work under extreme conditions' too: 1 3.68% of all jobs in the data bank show this characteristic, in control, steering and supervisory tasks, in transportation and vehicle handling, and in process industries. At first sight it seems astonishing that so many jobs and work systems which appear quite normal to the unprejudiced spectator, are rated 'extreme* in specific terms. With hindsight, the solution to this problem is quite simple. The division of labour in our industrialized society has led to such a diversity of jobs and workplaces that a sophisticated job analysis with several hundred separate items will classify most jobs as extreme in one or other respect. Were this not so, we would not have a national economy whose efficiency is based on the division of labour; differences in task, in environmental conditions, in responsibilities and risks etc., are the necessary ergonomic consequences. Thus, under this ergonomic perspective, we conclude: the 'extreme' is normal! Please note the singular in this sentence; the conclusion has to be then have a case of the revised if several extremes are diagnosed-we superimposition of stressors! Moving on from this introduction to the AET data bank, it is possible to pursue at least three approaches for the identification of extremes in workload and working conditions, where 'extreme' has to be separated from 'normal' via inductive analysis in empirical investigations:

2.1. Occupational physiology and occupational medicine The type, outward manifestation, and frequency of physiological symptoms, and consequently occupational disease, provide clues as to working conditions which can be classified as extreme. Physical and chemical (mostly environmental) stressors, and their compensation by physiological function and/or corresponding metabolism in the biological material with synergistic and anatomical effects, have to be considered: certain 'extreme' examples restricted to work under extreme physical conditions, like temperature, acceleration, and pressure can be identified (see section 3). 2.2. Work psychology and occupationaI cognitive science The number and severity of accidents and malfunctions in human-machine systems give an indication of human error, and from this a bridge is stretched to tasks, their generation, distribution, and interference in such a way that they are connected to an 'extreme' consequence, like an accident or catastrophic event (see section 4.1).

2.3. Stress and strain research in ergonomics

This tries to identify relative maxima and minima in the stress-strain relationship by


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time series analysis of working conditions on the one hand, and strain reaction analysis of working persons on the other (Rohmert 1987). For an ergonomic evaluation of design deficiency and necessity, not only the absolute maxima of a stressor configuration and stressor height are of interest, but relative maxima may be more appropriate in identifying 'overstrain' and 'understrain', and their respective workload causes (see section 4.2). 3. Work under extreme environmental conditions 'Superimposition' means that an environmental factor combines with a task in a way that a cumulative effect of the two load types on human behaviour, physiology, or perception, can be diagnosed. This accumulation is not limited to two influences; rather, it may occur with three, four, or more factors. However, systematic studies of these phenomena in ergonomics are mostly limited to two factors, because difficulties in the planning of respective experiments in re. factorial design tend to be manifest with more than two parameters. The literature on superimposition of stressors is quite rich with respect to two-factorial design, but seems rather poor with respect to combinations of more than two factors (Luczak 1982). Taking into account the richness of results in this line of research, documentation has to be limited here to factors which clearly demonstrate the effect of 'extremes*. Therefore I have (arbitrarily) chosen three physical environments with two extremes respectively on both sides of a bipolar distribution proceeding from 'normal' conditions. These are:

climatic influences, which range from 'extreme cold' through 'comfortable' conditions to 'extreme heat'; influences of gravity and acceleration, which range from one extreme (0 g) in space, through 1 g on Earth, to multiple g tasks in moving vehicles; influences of atmospheric pressure, which range from low pressure in high altitudes, 'normal' pressure at sea level through to high pressure in for example, diving tasks.

In all these 'extremes', a strong interference between 'performance' in respective tasks and environmental factors can be diagnosed. 3.1. Extreme climate and workload

The population of the world is not equally distributed; nor is the productivity of nations. It is obvious that population density is highest in the moderate zones, and that the prosperity of national economies seems to have something to do with natural climatic circumstance. Extremely hot and extremely cold zones are, to a certain extent, avoided by humans because of the extreme physiological 'costs* with arise there for a homothemic organism. Artificial extremes in climatical working conditions are a problem in the mining industry (due to geothermic heat and humid processes), and of process industries, which use heat for the modification of materials, like iron and steel, ceramics, and glass. Mining seems to provide an illustrative example for the superimposition of different stressors in the sense mentioned above, because extreme climate combines with extreme confinement, a considerable workload for miners, and a comparatively high degree of acute danger and probability of occupational disease (figure 5).

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Work under extreme conditions


air temperature Figure 5. Comparison between geographical (natural) and' workplace-related (artificial) climate (modified from Piekarski 1985 and Amegbey 1987). kc01 / h


500 400.


nBLRd..... .:...-..

..... ..... ..... ..... ..... .....




.... 200.

..... ..... ..... ..... .......... warm ..... ..... ..... ..:::. ..... ..... ...

2 hours

.::a ::


. , a .

basic effective temperature BET Figure 6. Limits of tolerability for naked men (from Wenzel and Piekarski 1980, using data by Wenzel from laboratory studies, and by Wyndham from field studies in gold mines).

A comparison of climatic zones in different geographical locations and different mines shows that gold mining in Ghana (Amegbey 1987) and coal mining in Europe (Piekarski 1985) is extreme when a high physical workload is introduced under these climatic conditions. Models of thermoregulation and balances of heat production and heat transfer in the human organism indicate (Luczak 1979, 1984) that limits of tolerability are violated. It is no wonder, then, that productivity in Ghanaian gold mines under these extreme climatical conditions is very low (Amegbey 1987), because the energy expenditure for sitting (300 KJIh), standing, and walking, in combination with this climate, leads to excessive sweat rates which (in spite of drinking) reduce body weight between 3.1% up to 4.4% per shift (n= 193 workers). Mining work with approximately 1200 KJ/h is almost impossible under these extreme conditions, because the respective limits of tolerability lie far beyond comparative values from

H. Luczak










L O -

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rectal temperature

Figure 7. Death rate with 3 14 heat stroke victims, dependent on rectal body temperature (from Wenzel & Piekarski 1980, with data after Momison and Wyndham).

South African gold mines, and near absolute tolerance limits in short-term laboratory experiments under medical supervision (figure 6). With respect to the very extensive data from investigations all over the world on climate and work, and some recent literature surveys (Luczak 1979, Wenzel and





33 ' C 35

basic effective temperature BET

Figure 8. Frequency of heat stroke in South African gold miners (energy expenditure= 1-000 kllh in different climatical conditions) (from Wenzel and Piekarski 1980, after Wyndham).

Work under extreme conditionr temperature 150

rnin 130 a

e 5 C




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7 0 b 2 0a a 4 c0 3 610 a


80 *


100% i

rel. humidity

Figure 9. Heart rate of a (treadmill) walking man wearing shorts at different climates (from Wenzel and Piekarski 1980).

Piekarski 1980, Piekarski 1985, Eissing 1988, Peters et al. 1988), conc1usions for another hierarchical model of extreme conditions can be drawn which has a certain validity for the superimposition of stressors in general. The first criterion for an 'extreme' is that the conditions might be lethal. One scale with a certain predictive value which summarizes the effects of hot climate and physical workload, is the rectal temperature of the human body after heat stroke. It is obvious that with respect to a dose-effect relationship, body temperatures above 39-40°C are concomitant with a considerable and increasing death rate (figure 7). The second criterion for an 'extreme' is that the conditions might lead to an acute disease, or that the probability of an acute occupational disease of workers might lie above a limit that is socially acceptable. The discussion of social acceptance of such limits has ethical and economical dimensions which cannot be addressed here. If, for example, the limit were reduced to one nonlethal heat stroke per 1000 people per year, the BET combined with a workload of 1000 KJ/h would have to be limited to 32"C, and a lot of mines would have to be closed down (see figure 8). The third criterion for an 'extreme' is that measurements in functions of organic systems, which form a possible 'bottleneck' for body reaction to the superimposed stressors, might exceed certain limits, or destabilize during the duration of the shift. In the therrnoregulatory system, this might consist in loss of body weight, or in sweat rate, heat rate, or body temperature. Figure 9 shows the heart rate depending on a specific workload (walking in a treadmill) combined with different climatic conditions. The areas of compensation of the stressors in the sense of a stabilized physiological reaction can be clearly distinguished from those of a destabilized reaction. Thus physiological parameters indicate to what extent the stability reserves of organic systems are 'consumed' by working conditions.

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The fourth criterion for an 'extreme' is the maintenance of predetermined or self-set levels of performance under certain conditions. In design this criterion indicates the need to avoid performance degradation or decrement. It has become clear that physical workload interferes with climate in a trade-off function; either energy expenhture has to be reduced, or the climate has to be improved to a level at which heat produced by physical work with low energy efficiency can escape into the environment. Additionally there is interference with mental and information functions (see figure 10). To avoid drastic reactions in perception, reaction, combination, control, co-ordination, etc., an effective temperature (BET) of 27-29°C be maintained. A fifth criterion for an extreme could be a deviation from optimal conditions: In the case of climates this could be comfort areas, which are quite near to the mental performance decrement conditions. With respect to design it seems obvious that a cfimatization may be of advantage in order to get rid of heat perception and its effects on performance. In summary, work under extremely hot conditions has been investigated thoroughly. Useful standards on the basis of research results exist. In comparison, investigations on work under extremely cold conditions are rare. From military research some results, e.g., on the effects of immersion in cold water, or for a person at rest with scanty clothing, are available, but systematic studies on workload, clothing, and simultaneous reactions to cold climate are few and far between. This may be due to the fact that workplaces with a superimposition of stressors of this type were seldom found in the past. In the last decade the storing of food in cold depots has increased rapidly, and thus estimates of the number of workers in extremely cold environments have reached the level of several thousand in Germany. Most of them are transport workers who switch rapidly between inside and outside cold storage depots; the group with the most severe stressor composition are the so-called commission workers, who load different types of goods from store on to transport pallets

reaction perception calculation

control coordination

I 7




















1 35 * C

basic effective temperature BET Figure 10, Information processing performance over several hours, for naked men at difirent temperature (summarized by Wenzel & Piekarski ( 1 980) from different authors).

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Work under extreme conditions


eZd work In cold-storage depot ( t ~ -28 %)

0 warm up break

( t ~ +22 %)

Figure 11. Physiological reactions of a store worker over shift (after Forsthoff 1982).

according to customer requirement (Forst ho ff 1982). In the cold storage depot, the air-temperature is - 28°C with a very low absolute humidity. The air flow is beneath 0.1 rnh. In order to be protected against this climate the workers wear special threelayer clothing with an isolation of 2.75 d o and a mass of 9 kg. They work a 6-7 h shift in the cold on a schedule of 50 min work and 10 min warm-uplrest in a room at +22"C. To investigate work and cold stress, Forsthoff (1 982) measured energy consumption, heart rate, rectal temperature, skin temperatures at the trunk and at extremities, and blood pressure (figure 1 1). During working hours (from 6 to 13 on the abscissa), heart rate and rectaI temperature do not show significant reactions to the cold climate that deviate from reactions in a normal climate. Specific reactions to cold can be diagnosed in a decrease of skin temperatures at the trunk, and especially at the feet-up to 20°C-at the toes, skin temperatures decreases to 15°C. These decreases are combined with a strong perception of cold. Similar reactions appear with a person who remains naked at a room temperature of 16°C for 2.5 hours. As another typical reaction to cold, blood pressures increased up to 20 mm Hg due to contraction of the peripheral vasal system. Energy consumption was up to 5 kJ/min higher, because of shivering/trembling, than in normal temperatures with the same physical workload. The increased blood pressure values may indicate a pathogenical process. Epidemiological studies of this phenomenon are scarce.


Dangers linked to extreme cold are associated with accidents in winter time, or with ships in cold waters (Low and Goethe 1981). In industrial tasks, levels of performance are reduced if, for instance, manual assembly of small pans in cold environments is necessary: between a skin temperature on the uncovered hand of 1 So-10°C a dramatic decrease of performance is found, which signals 'extreme conditions' (figure 12).

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mean value from 6 subjects

big nuts A

small screws

skin temperature at the hand

Figure 12. Decrease of motor performance of the hand, dependent on skin temperature (from Piekarski 1985).

rectal temperature Figure 1 3. Likelihood of survival with different rectal temperatures (from Piekarski 1 985, based on data by Molnar, Morrison, Hayward, and Golden). A

Toleration of hot and cold conditions is quite different. Whereas in the case of hypothermia the chance for survival decreases from 100% to 25% within a range of 8°C rectal temperature, in the case of heat strokes, the same decrease occurs within a range of 5°C: the stability reserve of the human thennoregulatory system is strong with respect to heat production in the cold, whereas the 'physiological costs' of extreme heat and heat transfer from the body are comparatively high within a narrow range of adaptation (figure f 3).

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Work under extreme conditions


3.2. Extreme acceleration and work .Extreme acceleration from + multiple g to 0 g are a problem inherent in technological development: the mechanical forces encountered by humans special environments are created mostly by modem machines, such as traffic systems and spacecraft. Multiple g environments (excluding mechanical vibration) occur mainly in high speed aircraft in specific flight or emergency situations, with rather short durations of fractions of a second, or perhaps a few seconds. The g-limits with respect to lethal consequences, tissue damage, physiological effects like liquid displacements and blood-pressure regulation, as well as voluntarily perceived intensities are well known, and available in summarized form for some time (for instance Damon and Stoudt 1963). The effects depend mainly onbody support, body orientation with respect to the force direction, the rate and duration of the force application, and the force magnitude. Within a multiple g environment, active working processes are almost impossible, but physiological and behavioural strategies are made to avoid possible black- or greyout, so as to maintain the ability of reacting directly after the exposure; whereas accelerations in fractions of 1 g above normal, on the other hand, do not severely affect worhng processes during the short durations in which they usually occur (see figure 14). 'New' insights with respect to acceleration on the other side of deviation from norm are available with respect to microgravity or 0 g effects in space operations. Weightlessness is a special case of prolonged acceleration at 0 g. This 0 g condition is superimposed to extreme confinement and isolation, because space capsules tend to be small, austere survival systems distant from human society. Under these extreme conditions, experts are required to perform extremely complex tasks, such as piloting, experimentation, and operation of research apparatus. The risk of not returning from space missions is higher than that for 'normal' travel, and radiation intensities are far higher than on earth. So we find a superimposition of different 'extremes' with respect to this 'work'. What kind of work is done under such extreme conditions? Beyond the piloting phase at take-off and landing, operations centre on the scientifically unique feature of the microgravity environment found near the center of mass of the space station. From experiments conducted with aircraft in parabolic flight, with rockets, Skylabs, Salyuts, Mir, and some space shuttle missions, it is known that there are many biological and physical phenomena that are strongly influenced by acceleration due to gravity. So a new vista of scientific investigation and technological development is opened up (Banks and Black 1987). Space operations comprise a variety of activities (Koelle 1990):

-collection -conversion -refinement -handling, -assembly, -sustenance

and distribution of information; and distribution of energy, and movement of rnalerials; observation, and measurement of biosystems; control, maintenance, and repair of facilities, and movement of people.

To facilitate these operations, many different tasks arise, with various degrees of automation. These include in-orbit repair and maintenance of expensive unmanned satellite observatories, as well as caring for smaller experimental systems and research instruments attached to and contained within the space stations. The




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1rain -

Average acceleration in "fast servi~c'~ Comfort limit for acceteration Emergency deceleration

Normal acceleration and decaleration Emergency stop (braking

from 7 0 mph) Automobits


5 2.5

Normal stop Quick stop Emergency stop Crash (potentially rutviva ble)

Normal takeoff Catapult fokeoff



Crash landing (potentially survivable) Seat eiection Parachute opening at

40,000 ft

5-8 3-5 3 10 1.5

0.25 0.2-0.5

Parachute opening a t

6,000 ft Parachute landing

0.5 0.1-0.2

Figure 14. Approximate duration and magnitude of some accelerations (after Goldman and von Gierke from Damon and Stoudt 1963).

human role in space is centred around highly skilfed work in operating and maintaining highly complex scientific equipment,(McDonell 1984). From a psychological perspective, the sensorimotor performance is influenced by difficulties in perception and orientation in oculomotory, proprioreceptive, and haptic terms, as well as in the control and steering of movements and posture without mass gravity (NASA 1986), so that manual assembly and manipulation of parts may be seriously compromised. Physiological effects have been studied from short-term exposures in parabolic flight, from immersion in water (so-called neutral buoyancy conditions), and from real space flights of up to one year. Most of them are life sciences experiments, not

Work under extreme conditiom

70 1

directly related to work (Oser et al, 1990). The effects of weightlessness can be summarized as follows (ESA 1990):

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-blood volume is shifted from body extremities to the centre; -the body is dehydrated and body mass is reduced; -bone mass and density decreases as does muscle mass due to decalcification if there is a lack of physical exercise; -cardiovascular capabilities decrease, and orthostatic tolerance is diminished; -physical fitness (on the whole) decreases; -body length increases because of the extension of the unloaded spine; -the volume regulation of hormones, fluid, and electrolyte concentration is modified. All these effects are of minor importance for performance in 0 g, and need not be problematic, if after a space flight medical personnel are available to take care of the space crew. If however, missions to other planets with a gravity comparable to earth are undertaken, these physiological effects might cause restrictions for work on the other planet. Due to the selection and training of astronauts, dramatic physiological reactions, (about 80% maximum aerobic capacity, the metabolic cost for such activities) are found during EVA (extra-vehicular activities). In this type of work the astronaut has to move and work in a space suit in free space outside the capsule. Doubtlessly this situation causes extreme workloads in the sense that physical stressors during assembly, maintenance, or repair of elements of the spacecraft or spacelab ate superimposed on to mental and emotional stressors, caused by the importance and risk of the work (ESA 1990). Normally the astronaut accepts the inherent risk; reasoning that a human presence, vulnerable in comparison to robots, can only be justified by the extreme flexibility and high performance achieved by humans. . Crew dynamics contributes to successful space operations. However, with the advent of very long space missions, success will be reliant on the ability of astronauts to interact together synergistically, both in the spacecraft and on the Earth. In isolated and confined environments, individual performance is strongly related to the dynamic of the group's composition, organization, training, skill base, and common experience. From past studies of the Antarctic, nuclear submarines, etc., as well as reports of the W e t long duration space flights, it has been found that there is a qualitative difference between short (up to one month) and long duration missions. Success is contingent on human factors, including decision-making systems, the compatibility of crew-members, the degree of inter- and intra-group autonomy and control, skill mix, opportunity for creative activities, physical layout as it affects privacy, personal communication, group activities, relationship to family and friends not present in the group, role variety, clarity of mission goals and limits, and the possession of conflict management skills (IAA 1988, Finney 198 7, AERXTALIA 1990, ESA 1990). Consequently, problems of work in space in fact tend to be tackled by a proactive approach, via the selection and training of astronauts. Long duration space missions that require a lot of 'intelligent' work also require 'extreme' personnel selection. The conventiond philosophy of space flight programmes leads to selection processes which favour the human astronaut who is a male, handsome, tall, young, and fit, with academic degrees and flight qualifications-a man with the Right Stuff. Ergonomically, this is not as rational as it might appear. A 'cunning dwarf' might be a much better selection.

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He might be as intelligent and qualified as any other astronaut. He will not have the same problems of adaptation to different g-conditions, because his longitudinal extension, and consequently the orthostatic pressure differences in his circulation, are lower. The adaptation gradient is smaller. Long extremities, especially legs and feet, are not needed; big hands and finely co-ordinated arm movements are sufficient. Problems of food storage and excrement recycling are minor, if energy expenditure is reduced. Because energy expenditure is related to the body surface, all circulatory and respiratory functions should be concentrated in a trunk in the form of a ball with small surface area. The space for worlung, leisure, and sleeping can be reduced substantially in relation to the anthropometrical measures of a dwarf. Thus a considerable amount of transport weight can be saved or used for other purposes. '.

It seems apparent, then, that 'work under extreme conditions' here may require the 'extreme' working person in quite another sense than that understood today. The author gratefully acknowledges the contribution of the European Space Agency (ESA) to this discussion, gained from his experience as ergonomics expert in the HAMOS-group (Habilitation Module Systems) for the LTPO (Long Term Programme Specification). 3.3. Extreme air pressure (hyperbaric and hypobaric conditions) Work under conditions which are characterized by deviations from normal atmospheric air pressure at the workplace is performed by few working people. A lot of research results are well known from military applications, especially in flight and diving systems, by aerospace and underwater medicine researchers (Stegemann 1984; Szadkowski 198 3). Work under hypobaric air pressure conditions is mostly connected to a given altitude above sea level, because air pressure decreases according to the barometric altitude formula. This leads to an acute or chronical shortage of Ol(oxygen), and corresponding physiological symptoms with performance degradation. Excluding peracute 02-shortageswith possibly lethal consequences, we can discuss the effects of altitude on human work according to the figure 15, which shows schematically the share of respiratory gases as partial pressure in the lungs dependent on altitude. At sea level the partial pressure of H20is 6.3 KPa, of C025.33 KPa, of 0,13.3 KPa, with the rest determined by the pressure of N2.Though ventilation increases with a decrease of O2pressure, at an altitude of 6000 rn the relative O2pressure reaches the limit of 4 KPa; this value corresponds to serious deficits in cerebral function. Altitudes above 6000 m are not tolerable for unadapted humans. With the help of respiration masks and pure O2respiration, altitudes of up to 1 3 km can be reached. Above this limit, pressurized cabins are necessary to survive. Modem airplanes usually fly at an altitude of up to 11 km. Cabins are pressurized in this situation at values approximately equivalent to a height of 2000 m. If decompression occurred, nobody would survive, so that in case of such decompression, masks are made available, from which pure 0, can be breathed. Acute hypoxia leads to an increase in respiration and heart rate connected with a serious deterioration of performance, and with psychological change. The symptoms have a certain degree of similarity with those of drunkenness. The danger of an acute shortage of O2 for work lies in the fact that the working person is unable to assess

Work under extreme conditions height (in 1000 m) 0








W loss of consciousness 80 h



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peak of Mt Everest (8848 rn)

f g"

V) (0



0 respiration of air

100 %


life impossible without pressurized atmosphere

Figure 15. Composition of alveolar air with respiration of air (0-6000 m) and pure O1 (6000-13 500 m) under hypobaric height conditions (from Stegeman 1984).


Hlnes Smlth

U, S. A. Evans U. S.A.

R:ER"" hubell


Blmrtt Cammoudi

Temu Walde

Figure 16. Deviations in athletic records at the Olympic Games held in Mexico City in 1968 from m r d s at Games held at sea level (from Stegeman 1984).

hidher own capabilities and the risk, and eventually the resulting mistakes may lead to a fatal situation. Acute hypoxia is an extreme, which occurs very rarely, whereas chronic hypoxia has an-effect arr dl persons who workand live in the high kountain regions. To a -




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certain degree, humans are able to adapt to this 'extreme' situation by physiological mechanisms: increase in ventilation rate, chemical and numerical changes in erothrocytes, increase in blood volume and content of haemoglobin all lead to an increase of O2 transport capacity, and thus to a partial compensation for altitudinal efffets on performance. Interesting results were found during the 1968 Olympic Games in Mexico City, which took place at 2500 m above sea level (figure 16). At the Mexico Olympics, the maximal performances of highly trained athletes were documented. Performance in short competitions (2 min) showed a substantial decrease in maximal performance in relation to earlier world records. The diagnosis of a shortage in O2 is backed by physiological measurements: production of lactate during long competitions was higher compared to sea level, and blood ,glucose decreased with a steeper slope due to anaerobic energy production. It is interesting to note that work makes it possible to remain at high altitudes. The highest settlements in the Andes are found up to 5300 m. The workplaces of people living there-mines-lie some hundred meters higher. Attempts to settle people directly near the mines failed. Sleep deprivation, and loss of appetite and body weight resulted. Intense physical work seems to be a necessary incentive for the control loop of ventilation, to keep PO, in alveoli above critical limits. A special job-related extreme is connected to hyperbaric conditions in pressurized construction sites, like underwater caissons, tunnel buildings, diving activity at drilling platforms or in shipping. To keep a caisson free of water it has to be pressurized at a level at which air pressure exceeds the pressure of the water column above and around it. During diving the pressure of respiration air has to be increased in function of the depth to compensate the water pressure on the thorax. In both cases the human body is 'pressurized' in the same way as the environment and mechanical influences by pressure differences are compensated. The increased partial pressures of the different respiratory gases may lead to dangerous physical and physiological effects. Gases can be dissolved in liquids, including body liquids. With constant temperature, and depending on the gas, the effect is connected to the partial pressure of the gas (Henry's law). The partial pressure of the gas corresponds to its relative volume in a gas mixture (Dalton's law). With a relative volume 2 1% oxygen in the air and an atmospheric pressure of 1 bar, the partial pressure of oxygen is 0.21 bar. With increasing diving depth, increasing quantities of air gases are dissolved in blood and tissue (Henry-Dalton Law). O2does not follow this law because of its chemical reaction with haemoglobin; only very low quantities of it will be dissolved physically. The other components of air, especially N, (79%), however, follow the Henry-Dalton Law precisely. An increase in pressure by 1 bar entails an increase of dissolved N2in blood by 98 mM. N2 is soluble in lipide tissue to a greater extent than water (3-5 times). In the body fat, in the central nervous system, and in the bone-marrow, more N, will be dissolved. If divers rise too quickly, causing rapid decompression, N2quantities cannot be excreted by respiration and form bubbles in body liquids and tissues. This eflect leads to decompression disease in bones and joints, in the nervous system, and in other organs-the bends. Decompression disease can be avoided by correctly considering the deadlines for coming up from deep diving. In addition, compression diseases (barotrauma) may occur in the ear and lung. In the isopression phase during deep diving (>40 m), nitrogen narcosis is possible, with

Work under extreme co,nditions


direct feedback to behaviour and work. Mixtures of oxygen and helium respiratory gases are used to avoid this effect. There can be no doubt that humans are very sensitive to air pressure deviations. Respective working conditions have to be monitored and controlled. Consequently, in most industrialized countries, legal regulations for work in extreme air pressures exist.

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4. IP operatives under extreme workload


4.1. Tuk and error analysis The development of new technical systems in engineering disciplines, and the analysis of risk and mental resource in ergonomics converge toward similar questions. When does the complexity of technical demands reach or exceed the limits of human information processing capability? Under what conditions can operators of multiply-detennined technical systems no longer maintain system control, and so lose control over the link between action and the consequences of that action (Wisner 1989)? A vast amount of literature (Brown and Greger 1990) suggests that the human ability to correlate dynamic processes is rather low, especially if the variables in these processes change their states rapidly, and if the anticipation of change is impossible because of the stochastic signal characteristics of unforeseen action to reaction cycles. Accident and injury statistics demonstrate this. Another illustrative example may be seen at work in energy plant or process industries control rooms. Whenever monitoring on the interaction of different highly interconnected system elements fails, and whenever a considerable time lag in the action-reaction sequence hinders the operator's ability to obtain precise and immediate feedback on the consequences, the 'mental model' of the situation may degenerate to an 'irrelevant action' style (Zimofong 1990, Rasmussen 1985; 1990). The technicians' answer to these human limitations is Automation. Bainbridge (1983) clearIy outlined that this has its pitfalls too: the problem of control under conditions of 'underload' arises. The reliability of human-machine systems is not only critical under conditions of 'overload'; similar consequences with logical links to disaster can be diagnosed in a situation in which supervision, steering, and control of large-scale systems are left to operators who have lost their competence in system-handling due to the fact that they have been excluded from the information and decision flow by automated devices for too long. Consequently they are no longer able to master problems-neither in emergencies nor in normal situations. Any situation may become 'extreme' with respect to erroneous activities. If the notions of 'extreme' and of 'error' have something in common, it is 'deviation' that should be focused on. FoUowing Leplat (1989, 1990), the notion of error implies the notion of a standard, and of deviations from this standard. Prescribed tasks redefined tasks, activities for the expert analyst, and 'normal' activity procedures may serve as standards for the detection of errors (figure 17). In consequence this scheme also argues that 'work in modem hi-tech societies calls for a reconsideration of the notions of human error' (Rasmussen 1990). A general understanding, in cognitive terms, of human behaviour and social interaction in complex, dynamic environments leads to a better understanding of the phenomenon called 'error'. . An illustrative, and sobering, example in the history of automation seems to be the breakdown of the Chernobyl nuclear power plant in the USSR,where not only operator behaviour, but also the whole 'complex, dynamic environment' led to the



Em* t a W t x p m

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Type1d aron

Figure 17. Definition of errors as 'deviations' from intended task execution (Leplat 1990).

catastrophic event of a nuclear reactor explosion (Munipov 1990). In the Three Mile Island reactor catastrophe in Harrisburg, USA (Kemeny 1979), many of the causes of the event could be assigned to direct identification and manipulation errors of the reactor operatives, the Chernobyl event is more or less a direct consequence of management failure. At Three Mile Island, deficits in skill-based and rule-based information processing systems (Rasmussen 1990) can be detailed as follows: displays and controls were arranged so as to 'camouflage' their function; information overload was created by hundreds of partially irrelevant alarms, and the misinterpretation of signals; information documentation was handled by a process computer system, which was far behind real emergency development (with a time lag of up to 2 h); crew members and junior management had an irrational confidence in the safety of technology; operators were insufficiently trained to comprehend and handle emergencies; manuals and operational procedures were unclear, and did not build on experience in previous accidents. At Chemobyl, deficits in knowledge-based and social-interactive behaviour .

(Rasmussen 1990) seem to have played a dominant role in the accident generation. If something like a 'violation of nrfes-motive-effect' analysis is applied to the activities of the Chernobyl operatives, we find a sum of errors which are mostly due to the fact that by following imperative orders with respect to an intended test programme-which, by the way, was not authorized-the operatives brought the reactor into an unstable condition, with all automatic safety devices switched off (see table 1). Munipov (1 990) speaks of 'intelligent idiots', intelligent enough to act as reactor operatives, but not intelligent enough to be aware of the consequences of their actions. So the explosion was a consequence of at least three factors, namely the simultaneous switch-off of emergency cooling of the reactor, combined with a reduced coolant circulation through pumps (by steam bubbles in the coolant) and a

Reducing the reactivity reserve far below permitted value. Reducing power below the value previewed in the test-programme. Shutting off all main pumps for the transport coolant; energy throughput above limits. Blocking emergency signal 'two turbo-generators switchedoff. Blocking safety devices controls for water level and steam pressure in the separator. Shutting off protective safety system for an emergency (i.e., breakdown of substantial elements of the system); shutting-off the emergency cooling system. Avoiding starting-up the emergency cooling system during the test phase.

Performing the test, even though the reactor did not work properly.

Repeating test (if necessary) with turbo-generators shu t-off.

The reactor could no longer be controlled.

Operator error when shutting off the local automatic control. Fulfilling test programme objectives.

The safety controls of the reactor for the supervision of the thermal parameters were totally shut off. It became impossible to minimize the consequences of the accident.

The temperature of the coolant in the inner reactor circulation increased until near saturation point. Automatic shut off of reactor became impossible.

The emergency shut-off system became ineffective.


Overcoming the xenon-effect.


Rules-motive-effect violation analysis of Chernobyl operator activities (Memmert 1986, Munipov 1990).

Rule violation

Table 1.

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subsequent increase of temperature over boiling point in the reactive zone, combined with a momentary increase of reactivity in the reactor due to the construction of absorber rods after their introduction into the reactive zone. In his analysis, Munipov (1990) concludes, that the behaviour of operatives in this catastrophic event was not due to an actual feeling of extreme overload, anxiety, and fear linked to doubt in critical decision situations (Wisner 1989), but to built-in deficits in the whole system of the USSR's nuclear power plant operation, viz., I . Plant engineering management -the test was performed under time pressure; -imperative orders to operators were not questioned; -the violation of rules, modification of prescribed test programme, and deficits in reactor manipulation demonstrate the crew leaders' lack of comprehension for specifics of the technical process and their inadequacy regarding the evaluation of a dangerous situation. 2. Crew education and training -most crew members had no idea of the nuclear process and of reactor physics; -they displayed unquestioning confidence in the reliability of the reactor, -training in emergency situations was restricted to primitive algorithms of manipulation.

3. System and plant planning system was not resistant to operator errors; -project engineers did not foresee a coincidence in the switch-off of different safety systems; -the crew was not briefed on construction details concerning the absorber rods and their physical effect.


4. Communication and decision-making -secrecy in all nuclear power operations led to communications between state supervisors and plant management being hindered, and information blocked; -the increasing demands of energy consumption and an increasing nuclear power programme in the USSR created a shortage of qualified personnel, whose posts were filled by incompetents.

So work under extreme conditions with respect to task and error analysis is not restricted to experiences of acute, extreme workload by individual operators. The cocoon of management systems, of education and training systems, of planning and projecting technical devices, and of societal constraints, determines behaviour, and possibly 'extreme work conditions' (Moray and Huey 1988). 4.2. Stress and strain analysis

Some psychophysio~ogicalfindings, case studies, and respective conclusions may illustrate how the extremes, or the hypothetical scales and areas of extreme workload, can be identified by decomposition of strain reaction. In these situations the human as a worker plays a dominant role in the working process. He/she is not a passive sufferer, more or less a victim of an emergency or accident. Only people who are able to influence the 'extreme' situation they find themselves in are considered here (Luczak 1987).

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Work under ext teme conditions


4.2.1. Inductive interptetation of the 'stability reserve' in cardiovascular control: For an experienced ergonomist, there is no doubt that extreme reactions of the cardiovascular system, measured as increases of heart rate, have links with 'extreme conditions'. These reactions are mainly connected to components of physical workload, such as the type of work (static or dynamic muscular work), the amount of working muscle mass,.the speed and resistance (exerted force) of movement, and the climatic circumstances. If climate and physical workload are set at a constant (low) level, heart rate reactions can be assigned to mental and emotional workload. To identify what proportion of a physiological reaction can be attributed to any given stressor component, a sophisticated analytical measurement concept and a statistical data treatment model are necessary. An investigation of air traffic control (ATC) tasks (Rohmert et al. 1973) attempted to combine different stressor measurements in a time series analysis approach with the reactions of the heart rates of air traffic control officers. Air t d 5 c control seems to be an extreme task in terms of mental load: complaints and strikes are numerous and frequent. Physiological stress indicators also suggest such extremes; e.g., levels of heart rate reached in a sitting position in front of a radar screen (see figure 18). In the upper part of the figure the heart rate of an air traffic control officer (approach controllpick-up position at Frankfurt Airport) during the peak shift (rush-hour) is shown. Mean values are more than 1 10 beatdmin over a considerable time, and ranges go up to nearly 140 beatdmin. A comparison to results in the literature shows that with respect to face validity and similar reactions of heart rate, ATC-tasks are to be classified as extreme tasks. Comparable mean values of heart rate and deviations from conditions of rest are found only in .working conditions that combine a high density of information flow with a high degree of 'danger* or 'responsibility', as is the case, for instance, with test pilots, in various flight situations including parachute jumping, special (extreme) situations in other vehicles (sudden breaking of a train and automobile racing sports), production systems, and, last but not least in musical performances, stage-plays, and examinations (table 2). What makes this physiological reaction to this mental workload so extreme? An analysis of three different, simultaneously-registered workload variables (viz., difficulty coded by an experienced ATC-officer; number of planes expected; and number of planes under actual control) shows that reactions in the level of heart rate are determined with the highest correlation by the number of planes under control, that difficulty and number of planes under control are highly intercorrelated, that increases of heart rate mostly occur when the number of planes expected increases (i,e., event-related physiological response, anticipation of future stressor in strain reaction), and that even with constant (high) values of planes under control, heart rate increases depending on time (i.e., destabilization of physiological response due to overload). From t h s analysis a simplified prediction mode1 for the reaction of heart rate could be derived, viz., '

H R cf (planes controlled and shift time), which permits the deduction of an (extreme) physiological response from external stressor components. Summarizing the results of analyses performed on 66 ATC officers at Frankfurt Airpon (figure 19), 'extreme conditions' can be predicted. At the ordinate the relative change of heart rate from a basic level is shown, at the abscissa

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Work under extreme conditions

71 1

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the number of airplanes under control, the parameter in this diagram is shift time. According to this diagram, ATC becomes an extreme task between 4 and 6 airplanes controlled, because beyond this area shift time has an increasing influence on the relative variation , of heart rate. In occupational physiology, as well as in psychophysiology, such a destabilization in dependence of a level of workload is a clear symptom of an 'extreme' overload. So from only one physiological variable, a diagnosis of extremes can be made. This approach, however, neglects all physiological systems other than that chosen for registration. It thus seems appropriate to follow the effects of 'extreme' mental and emotional workload through different physiological systems.

number al planes

6 . controDed 4 , 2




shift time

Figure 18. Strain, measured by heart rate, in dependence of stressor variables with an ATC task.

4.2.2. Inductive strain component analysis: The inductive strain component analysis was facilitated by a polygraphic measurement concept, in an attempt to folIow the psychophysiological interdependencies in the measurement of different frequency bands in the electroencephalogram, of catecholamine secretion, and of cardiorespiratory parameters. This strain component analysis focused on an extreme workload-university examinations. It tried to relate the dynamics of various physiological systems to each other within a concept of tonic and phasic, mentally-

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H. Luczak


and emotiondly-induced arousal (Luczak ei al. 1980). Teachers in universities have no doubt that among the pedagogically relevant tasks for students' examinations is 'work under extreme conditions'. The examinations were held in oral form (see time line analysis in figure 20). he) began with a report on the thesis (lecture), which was followed by a discussion between the candidate and the audience about the results presented. This part was followed by an oral examination by the professor, which ended with the examinee being advised of the mark achieved. The whole process was called a 'colloquium'. As a control for the individual dynamics of physiological reactions, a phase with a standardized stressor situation before and after the experimental phase was introduced. For this purpose, a 10 min mental arithmetic test was chosen. Five male subjects with an average age of 26 years were involved in the experiments. From a telemetric recording of ECG,heart rate (HR) and heart rate variability (ARQ) were calculated. From EEG,the beta and theta bands were filtered out and integrated over time (EA- EEGIB or T respectively). In addition, urine samples were taken to determine catecholamine secretion, and respiration rate (RR) was registered with the help of a nasal thermistor. 1n figure 20 the time behaviour of the different indicators for one of the experiments is shown. The plotted values Y,(t) are means of 1 min Y,(t), which were normalized with respect to the mean value of the control period Y after the end of the colloquium. rel. variation of strain %

time on task min

number of airplanes controlled

Figure 19. Relative variation of strain, measured by hean rate, in dependence of stresson in an ATC task.

The neurophysiological indicators' timedependent behaviour shows a reaction to stressor activity with respect to the task content. At the beginning of the lecture thetaactivity increases rapidly, followed by a steady state on a lower level until the end. Subsequently, theta-activity decreases to a level which is maintained approximately

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Work under extreme condir ions



7 13


a 0)






E t




Tmrt control


Figure 20. Variations of synchronously-recorded physiological indicators of strain during university examinations. RR =respiration rate; ARQ = scored heart rate variability; HR heart rate; EA-EEG/T = EEG theta activity; EA-EEGIB EEG beta activity.



until the end of the task. This shape of the curve, with its typical reactions for emotional strain and tonic arousal at the beginning of the task, corresponds to the heart rate behaviour. Beta activity shows the same rapid increase at the beginning of the lecture. Further behaviour is influenced, to a greater extent, by the task demand for continuous information-processing, i.e., mental strain and phasic arousal. This can be seen clearly in, a higher level and lower variability during the mental arithmetic test in comparison to the adjacent rest phases. The behaviour of the ARQ, however, is less uniform. Whereas the decrease of the ARQ in'the study shown in figure 20 corresponds to a remarkable increase of heart rate, in the other experiments (n-4), with a comparibly smaller increase of heart rate, the ARQ shows a decrease, too, but only down to the level of the control period. In table 3 the results of the analysis of catecholamines for adrenalin secretion are presented. Adrenalin values are already increased in the period preceding the colloquium, in comparison with the control values. This is caused by the emotional stressor component with respect to the expected stress condition (i-e., anticipative effect). A further increase can be diagnosed during the period of the colloquium, whereas the values recorded immediately following the colloquium again decrease to the level of the control values (i.e., relief effect). All values during the colloquium show a uniform significant increase in comparison to control values. An intercomelation analysis of the different variables shows (see Luczak et of. 1980) that 'extreme' emotional strain and tonic arousal can be derived from adrenalin secretion, and consequently from humoral increases of heart rate, as well as from EEG theta activity. 'Extreme' mental strain and phasic arousal seem to be -

H. Luczak

7 14

Table 3. Urinary excretion of adrenalin during university examinations in comparison to control periods (see Luczak et al. 1980). Urinary excretion of adrenalin (ng ml-I)

Control.measurements -

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Mean values



Measurements under stress' -

2 h before




2 h after

Taking the colloquium.

* Significant at p-0-05.

Mean values and standard deviation (SD) calculated over n days during the control period.

indicated by EEG beta activity and ARQ, if the ARQ-reaction is not depressed/camouflaged by 'extreme' heart rate increases.

4.3.3. Inductive stressor component analysis: With respect to arousal theory, a distinct analysis of the psychophysiological reactions to extreme situations by time line analysis of events-in the sense of a broad classification of types of tasks-and an event-related decomposition of physiological responses, does not guarantee that assigned to design variables, which the ergonomist could then the 'extremes' can bem work on. External stressor variables have to be connected to internal strain reactions of work so as to identify the cause-and-effect relationship in 'extremes'. Field studies on ships (Rohmert et al. 1975) suggest that together with characteristic situations, event-related physiological responses up to extreme heights occurred in ship-handling (figure 2 1). Ships are massive technological systems, and their handling is difficult, and influenced by many unforeseeable events, such as crosswinds, currents, and the changing traffic situation. A manoeuvre which appears correct at one given moment may become dangerous at the next. Hence time delays in the reaction of this huge system (think of a supertanker or a containership) to signal inputs may lead to disastrous consequences. With the help of 20 merchant marine officers, we studied shiphandling in narrow waters on an authentic shiphandling simulator (Luczak et al. 1986, Schiitte et a1. 1985). The empirical data for external stressors were connected to internal strain variables by a canonical correlation. This multivariate statistical procedure calculates the coefficients a, and b, of a stress-strain-function g(b, y,)-Aa, xJ in a way, that the two functions g and f are connected with maximal correlation (i.e., canonical correlation). Because tasks in nautical shiphandling are determined by the situation of the ship, changes in the situation lead to variations in task structure (e-g., control of position, observation of weather and sea conditions, track control, etc.). Hence the stressors during shiphandling are generated by the situational conditions, with their

Work under extreme conditions heart rate


--.-.--.. 23.n 23.30

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heart rate

.f, : 60


01.07 01.10




,, ; , ,,,A


01.30 hour

, , , , ;, , , , , ,

L-.'-;*..B..l 24.00



Figure 2 1. Event-related physiological response in ship-handling: A: exit from channel into windy and rolling river; B: exit backwards from harbour to narrow lock with crosswinds.

specific demands on information perception, information handling, and transfer to action. Proceeding from the hypothesis that task structure is reflected by the frequency of interaction with instruments, displays, and controls on the bridge (radar, etc.), a registration of these activities may document stressor structure. The psychophysical strain variables which result from information processing on the bridge were operationalized by physiological measurement of hean rate, rn.fronralis, EMG and eyelid blinking frequency. In the canonical correlation, the stressor variables (frequencies of observation and operation of important information sources for shiphandling) were combined with the strain variables for five different traffic situations, viz., -situation -situation -situation -situation -situation

I 'oncoming traffic'; I1 'radar defect'; I11 'open sea'; IV 'change of course'; V 'fishing boats and roadsteads'.

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H. Luczak

Figure 22. Canonical correlation of stress and strain variables in five shiphandling situations.

These situations have different influences on stress-strain relationships. In spite of a similarly high canonical correlation between the variables (0.92-0-97), the structure of stress-strain relationships is differentiated according to coefficients a and b. With the help of these coefficients, distinct conclusions about extreme situations can be drawn. In situation 1 measurements to avoid collision with the oncoming ship are predominant. In situation 11 the radar defect leads to working processes concerned with failure compensation using other nautical devices (e.g., map) for positionfinding. In situation 111 manoeuvre planning for the future course is predominant. In situation IV, supervision and control of the changed course predominant. Finally, in

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Work under extreme conditions


situation V, course and speed adaptation to conditions of narrow waters predominates (see figure 22). If the shape of the curve of heart rate reflects emotional strain, if that of electrical activity of m. frontalis indcates common attention, and if that of eyelid blinking frequency indicates voluntary activation, a similarly differentiated picture of psychophysical strain in connection. with the stressor situation is suggested. In all traffic situations, the reactions of the m. frontalis EMG is quite similar, demonstrating-a_high and constant level of attention. Emotionally extreme reactions occur in the situations I1 and 111, where heart rate indicates the effects of the radar defect and of the machine failure. In the situations I and V, where an evaluation of collision courses and critical distances for passing is .necessary, eyelid blinking frequency reacts dramatically. Thus the relative extremes of physiological responses can be assigned to observations, related to task execution, that is, information-handling devices and their relative importance. These provide clues to the marine ergonomist for the design of bridges and ship-handling procedures.

5. Conclusions Work under extreme conditions is determined to a considerable extent by notions of 'deviation' and 'adaptation'. There must be a certain distance from what is classified as 'normal', 'prescribed', or 'acceptable', and there must be something like a mismatch between the objective situation, e.g., external demands, etc., on one side, and subjective capability, e.g., reactions, behaviour; etc., on the other. However, what may be classified as 'extreme' depends on the classifier's viewpoint. In scientific terms this may be outlined as the phenomenological aspect. In physiological terms, a necessary condition for an 'extreme' may be that organic systems of control of physiological functions are deviated/destabilized until near their stability reserve. The dynamics of responses to a stressor are completely or approximately exhausted. Life functions reach the limits of their possible ranges, or exceed preset tolerability standards. In psychological terms we would speak of 'work under extreme conditions',


when high information processing rates under time pressure .with a high probability of error and negative consequences of erroneous action can be identified; when sensory deprivation and isolation or an overflow of stimuli with the character of control, hostility, or threat to a person can be diagnosed; when internal and external conflicts of the individual about goals and consequences of actions occur, when the abstractness and size of a mental model or a situation is so large, that predictions about the behaviour of partners, enemies, technical systems, etc., in this model become uncertain; when the risk of failure, or of not reaching the intended performance standard, increases, especially when the individual level of motivation to perform in an accepted manner is high.

In technological terms system characteristics may be classified as 'extreme' when a high frequency of action-reaction cycles occurs; when interventions in systems dynamics are risky; when it is difficult to foresee the consequences of action; when it is



H. Luczak

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impossible to correct errors; when catastrophic events may occur; and when responsibility for t h e functioning, and the destruction, of the system is assigned. In economic terms, 'work under extreme conditions' takes place when high values are disposed over in risky transactions; when the consequences of decisions are unclear; when responsibilities for material and people's welfare are high; and when losses of jobs are possible or probable. In sociological terms, working conditions may become extreme, when rules are violated; when a societal attention is concentrated on the activity; when social sanctions or even a criminalization of activities are possible; and when negative feedbacks from the surrounding society are imposed. References AERITALIA (SPACESYSTEMS GROUP)1990, Habilitation module definition for EMSI-Habemsi, report, Turin, October. AMEGBEY,N. A. 1987, Investigation into human factors with special reference to health and environment conditions in the Ghanaian underground gold mines, Doctoral dissertation D 83, TU-Berlin. L. 1983, Ironies of automation, Automatics, 19, 775-779. BAINBRIDGE, BANKS,P. M. and BUCK, D. C. 1987, The future of science in space, Science, 236, 244-245. BROWN, 1. and GROEGER, J. (eds) 1990, Errors in the operation of transport systems, Ergonomics, 33(lO/ll), special issue. DAMON, A. and Sromr, W. 1963, The mechanical environment, in C. Morgan, J. Cook,A. Chapanis and M. Lund (eds), Human Engineering Guide lo Equipment Design (McGraw-Hill, New York). EISSING, G. 1988, Klirna am Arbeitsplarz-Messun und Bewertung (Beuth-Verlag, Berlin). EUROPEANSPACE AGENCY1!Boa, Proceedings olzhe SN W-Space Habitability Workrhop March 1990, ESANPP-015, Paris. EUROPEAN SPACEAGENCY1990b, Human requirements for extended space flight, Report from Avignon Working Days, LTPO-SR-90-02, Paris. FINNEY, B. R. 1987, Anthropology and the humanization of space, Acra Asrronautica, IS, 183-1 94. FORSTHOFF, A. 1 982, Arbeitsphysiologische Untersuchungen bei Arbeit in - 28"C,Zeitschrifr f i r A rbeifs wissenschafr, 36(3), 1 85- 1 8 8. INTERNATIONAL ACADEMYOF ~ ~ R O N A ~ 1I988, C S The case for an international lunar base, Acta Asrronaurica, 17 (S), 463-489. &MEW REPORT1979, Der StZirfaN von Harrisburg, mit Stellungnahmen von R. Jungk und W. Miiller (Erb Verlag, Diisseldorf). KO=, H. H. 1990, Orbital operations in perspective, Space Technology, 9(1/2), 5-1 0. LANDAU, K. 1984, Belastungsanalyse mit dern arbeitswissenschaft1ichen Erhebungsverfahren zur Tiitigkeitsanalyse (Vortrag anlaolich eines Symposiums des REFA-Verbandes 14-1 5.6.84, Bad Nauheim). LANDAU,K.,LUW, H. and ROHMERT, W. 1975, Arb~itswi~~ens~haftlicher ~rhebungsbo~en zur Tatigkeitsanalyse, in W. Rohmert and J. Rutenfranz (eds), Arbeitswissenschof!liche Beurteilung der Belastung und Beanspruchung an unterschiedlichen industriellen Arbeitspldtzen (Der Bundesminister fur Arbeit und Sorialordnung, Bonn). LEPUT, 1. 1989, Error analysis, instrument, and object of task analysis, Ergonomics, 32(7), 8 1 3-822. LEPUT,J. 1990, Relations between task and activity: elements for elaborating a framework for error analysis, Ergonomics, 33(10/1 I), 1 389- 1402. Low, A. and G o ~ E H. , 198 1, Hypothermiebehandlung eines Besatzungsmitglieds nach Untergang eines Kiistenmotorschiffs, Med. Welt, 32, 828-835. LUCZAK,H. 1979, ArbeitswissenschaftIicheUntersuchungen von maximaler Arbeitsdauer und Erholungszeiten bei informatorisch-mentaler Arbeit nach dem Kanal- sowie ReglerMensch-Model1 sowie superponierten Belastungen am Beispiel Hitzearbeit, Fonschritt-

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LUCZAK,H. 1982, Gxundlagen ergonomischer Belastungssuperposition,in W. Rohmert (ed.), Ergonomie der kombinierten Belastungen (Schmid t-Verlag, Koln). LUCZAK,H. 1987, Psychophysiologische Methoden zur Erfassung psychophysischer Beanspruchungszustande, in U. Kleinbeck and J. Ruten franz (eds), Arbeitspsychologie (Hogrefe, Gottingen). Lucwc, H. and GE, S. 1989, Fuzzy modelling of relations between physical weight and perceived heaviness: the effect of size-weight illusion in industrial lifting tasks, Ergonomics, 32,(7), 823-8 37. L u c u ~H., , NIES,R., ROHMERT, W. and ZIPP,P. 1 984, Beurteilung und Gcstaltung van Hitzearbeit besonders in GieJereien (GieBerei-Verlag, Diisseldorf). L u c u ~H., , PHILIPP, U. and ROHMERT, W. 1 980, Decomposition of heart-rate variability under the ergonomic aspects of stressor analysis, in R. I. Kitney and 0. Rompelman (eds), The Study oj'Heart Rate Variability (Clarendon Press, Oxford). LUCZAK, H. el al. 1 986, Belastungs- und Beanspruchungsuntersuchungen rum Schi'der Zukunfr (Wirtschaftsverlag, Brernerhaven). MCDONNELL DOUGLAS A ~ O N A T ICO. C S 1 984, The human role in space, Report MDC H 1 295, Huntington Beach, CA. MEMMERY, G.1986, Der Reaktorunfall in Tschemobyl, Forschung akruell, 3, 3-6. MORAY,N. P. and HUN, B. M. (eds) 1988, Human Factors Research and Nuclear Safety (National Academy Press, Washington, DC). MOW, R. 1982, Arbeit in der G l t e , insbesondere beirn Lijschen von Frost- und Frischfisch. (Forschungsbericht 298, Bundesanstalt fur Arbeitsschutz und Unfallforschung, Dortmund 1982). Mmrmv, V. M. 1990, Der menschliche Faktor bei Havarien in den Kernkraftwerken Tschernobyl und Three Mile Island, in Gottlieb Daimler- und Karl Benz Stiftung (ed.), 2. Internationales Kolloquiurn Leitwarten, (Verlag TUV Rheinland, Koln). NASA, 1986 Psychological effects of space flight, PB 86-86 68 52IXAD. OSER, H. et al. (eds) 1990, Life sciences research in space, 4. European Symposium in Trieste, Italy, ESA-Special Publication 307 (ESA Publication Division, Paris). PITERS,H., MU-, B. and H ~ G E T. R 1, 988, Beurteilung der Klimabelastung (Beut h Verlag, BerlinlKoln). PIEKARSKY, C. 19 85, Zur arbeifsmedizinischen Bewerrung der Beanspruchung des arbeirenden Menschen unier Hitzebelmtung (Bellmann-Verlag, Dort mund). ~ S M U S S E N ,1. 1985, Trends in human reliability analysis, Ergonomics, 28, 1 1 85-1 195. ROHMERT, W. et al. 1973, Psychophysische Belastung und Beanspruchung von Fluglotsen (Beut hVerlag, Berlin). ROHMERT, W. and LANDAU,K. 1 979, Dar ArbeitswissenschajXchr ErhebungsverJahren zur Tutig-keitsanalyse (AET) (Verlag Hans Huber, BernlSt uttganlwien). ROHMERT, W., RUTENFRANZ,J. and LUCZAK,H. 1975, ArbeitswissenschaftlicheBeurteilung der Belastung und Beanspruchung an unterschiedlichen industriellen Arbeitsplatzen, Forschungsbericht, der Bundesminister fur Arbeit und Sozialordnung, Bonn. S C H ~ ~ T M., E , SCHWIER, W. and LUCZAK,H. 1985, Informatorische Belastungen und Beanspruchungen bei einer simulierten Schiffsfuhrungsaufgabe, ZeilschriJt fur A rbeitswissenschaJ, 39( I), 39-48. STEGEMANN, J. 1984, Leistungsphysiologie (Thierne Verlag, StuttganlNew York). SUDKOWSKI, D. 1983, Ungewohnliche Luftdriicke, in W. Rohmert and J. Rutenfranz (eds), Praktische Arbeitsphysiologie (Thieme Verlag, StuttgartINew York). WENZEL,G. and PIEKARSKI, C. 1980, Klima und Arbeit (Bayerisches Staatsministerium fur Arbeit und Sozialordnung, Miinchen). W I S N ~A., 1989, Fatigue and human reliability revisited in the light of ergonomics and work psychopathology, Ergonomics, 32(7), 89 1-898. ZIMOMNG,B. 1990, Fehler und Zuverlassigkeit, in C. Graf Hoyos and B. Zimolong (eds), Ingenieurpsychologie, Enzyklopadie der Psychologie, D I11 2, (Verlag fii r Psych 01 ogie Dr. C. J. Hogrefe, Gottingen/Toronto/Ziirich), 3 13- 345. Extreme Bedingungen werden als Abweichungen von Normalitatsbereichen und Anpassungsmf ngel zwischen Anforderungen und Personeneigenschaften definiert. Durch eine Hiufigkei tsanalyse von ausgewahlten Extreme-in der AET-Datenbank wird die Bedeutung


Work under extreme conditions

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solcher Bedingungen erlautert. Ais Beispiele fur Arbeit unter extremen Urngebungsbedingungen wurden HitzearbeitlUltearbeit, Arbeit unter x-g, sowie Abeit in verschiedenen Luftdriicken nach Einwirkungen und Auswirkungen diskutiert. Als Beispiel fiir Operateure unter extremen Arbeitslastbedingungen werden KK W-Operateure (Chernobyl), Fluglotsen, Priiflinge und Nautiker in Fallstudien nach Belastungs- und Beanspruchungsgesichtspunkten hinsichtlich ihrer Reaktionen analysiert.

Work under extreme conditions.

Extreme conditions are defined in terms of deviation from the norm, and the mismatch between capacity and demand. Analysis of ergonomic job descriptio...
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