Ergonomics
ISSN: 0014-0139 (Print) 1366-5847 (Online) Journal homepage: http://www.tandfonline.com/loi/terg20
Ergonomics and Occupational and Public Health Surveys STANISLAW KOZLOWSKI & PIOTR KRASUCKI To cite this article: STANISLAW KOZLOWSKI & PIOTR KRASUCKI (1979) Ergonomics and Occupational and Public Health Surveys, Ergonomics, 22:6, 651-659, DOI: 10.1080/00140137908924650 To link to this article: http://dx.doi.org/10.1080/00140137908924650
Published online: 27 Mar 2007.
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Date: 07 November 2015, At: 00:42
ERGONOMICS, 1979, VOL. 22, No.6, 651-659
Ergonomics and Occupational and Public Health Surveys By STANISLAW KOZLOWSKI and PIOTR KRASUCKI Warsaw. Poland Hygiene standards used in occupational medicine were created for health protection. How-
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ever. there is apparently no agreement as to what is health and how it can be measured. This
paper reviews the various criteria for health, used in the past 15-20 years; it evaluates approaches which attempt classifications of exposure to risk via levels of reversible and irreversible disease; it criticizes methods used for work-description; and supports procedures for establishing dose-effect and dose-response relationships in specific work situations. The general conclusion is that public health surveys should be based on exact knowledge of the social anthropology of the investigated population, which determines acceptable . comfort zones' for all life conditions. Ergonomie Appliquee aux Enquires de Medecine du Travail el de Sante Publique. Ergonomie fUr Berufliche und OjJentliche Gesundheitsiiberwachungen
1. Introduction The aim of occupational and public health surveys is first and foremost to find the factors which are responsible for changes in the health status and well-being of the population. Generally, in these surveys, we can use methods developed for epidemiological studies. We have to select a population which will be examined and divide it into groups' exposed' and' not exposed' to a risk, according to the relationship between the factors which are the object of our research-and the real situation of persons in the investigated population. This is a very simple process if we are studying factors such as sex, age, marital status, or profession, because in these cases we have unmistakable criteria: someone is a man or a woman; he is above or below a predetermined age criterion; he may have one child or two children; and so on. But problems arise if we want to subdivide the population using, for example, criteria connected with physiological or hygiene standards.
2. Criteria of Health Hygiene standards used in occupational medicine were created for health protection. But we have no agreement as to what is 'health' and how it can be measured. The variety of health indices proposed from the time of Stouman and Falk (1936) until the present day is a sure sign that wehave no 'ideal' index of health. The definition recommended by the World Health Organization and based on a former proposition ofSigerist (1941) takes into account not only the absence of disease but, also the individual's physical, mental and social well-being. The suggestion of Sigerist was that health' is something positive, ajoyful attitude toward life and cheerful acceptance of the responsibility that life puts on the individual'. In a review of methods of health measurement published by Sanders (1964), it is proposed that they should take into account the' functional adequacy of an individual to fulfil the role which a healthy member of his age and sex is expected to fulfil in his society'. 0014-0139/79/220f> 0651 $02.00
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We can extend this definition to include Frankl's (1975) theory, which stresses that an indispensable condition of health is to have a 'will to meaning', or 'purpose in life', because the lack of it leads to psychosocial disturbances. However, in practice we have to apply a simpler criterion of health. Thus, health indicators described by Leowski (1978) are divided into: indicators connected with life expectancy and mortality rate; indicators of morbidity and disability; and socalled indicators of positive health. This last group of indicators is used for the evaluation of health status of the newborn and children; because its' standards' with regard to adults are uncertain. The choice of health indices depends upon the kind of epidemiological methods used. In retrospective studies we can use mortality statistics as shown by Selikoff (1972) in his study of asbestos dust and cancer. In prospective studies we must use indirect indices, such as the analysis of sickness absenteeism and the number of visits to the doctor. Although Taylor (1968) described cases which he termed' resistant', where sickness absenteeism occurred regardless of health status, these are only isolated incidences. For commonly used methods of analysis, these indirect indices are usually sufficiently accurate. In many publications we can find results of investigations based on such indices: for example Thiis-Evesen (1957) has studied the relation between morbidity and shift-work; Shephard and Walker (1957) looked at absenteeism and work-load; and Forssman (1955), Fortuin (1955), Indulski (1965), Krasucki (1976), and Lokander (1962) have analysed many other social and environmental factors in relation to sickness absence level. In the past few years (WHO 1975and 1977)two new terms have been introduced: (I) the dose (uptake)-effecl relationship; indicating the relation between the uptake of a chemical and the magnitude of a qualitatively specified affect on an individual, (2) the dose (uptake)-response relationship; indicating the relation between the uptake of a chemical and the proportion of individuals with a quantitatively specified magnitude of a qualitatively specified effect in a group of subjects. We can now estimate the degree of toxicity of chemically harmful agents. We have an idea of the standardization of methods used in establishing permissible levels in occupational exposure to harmful agents. Based upon data such as qualitative biological effects (e.g. decreased blood haemoglobin concentrations, or impaired psychomotor performance) and the intensity of some of these effects, or the proportion of subjects affected, we can describe various levels of the dose-effect relationship and also of the dose-response relationship. The measurement of the impairment of physical health in relation to the uptake or dose is relatively easy with regard to chemically harmful agents and industrial dusts. We can record continuously the concentration of these agents in the air, and we can estimate their absorption. We must remember, however, that the uptake of chemicals or dusts depends not only on their concentration, but also on factors such as: body size, the respiratory minute volume expenditure required by the workload and by the barometric pressure, the duration of work in given conditions, etc. Also significant may be the compound physico-chemical characteristics which determine its pharmaco-kinetic fate, the proportion of the respirable fraction andlast but not least-individual or group differences in reaction, due to such factors as genetic traits, nutritional status and others. Because of these differences, Truhaut (1970) suggested that 'maximum tolerable concentrations represent average concentration to which workers may be exposed during the eight hours of their working
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day-excluding cases of hypersensitivity'. In addition, Stockinger (1970) suggests that hypersusceptible workers ought to be excluded from analyses of the uptake: effect relation. Sanotzky (1970) defined maximum allowable concentrations as 'concentrations that, by their action on exposure of the human body, periodically or throughout life, directly or indirectly, will not cause the development of physical or mental disease including latent or temporarily compensated conditions or changes in the state of health that go beyond the limits of adaptive responses detectable by modern methods of investigation, either immediately or in the long term in this or in subsequent generations' . In spite of these demands, Krichagin (1977), dealing with protection categories on eight levels writes: 'The ideal goal of health authorities is to obtain protection standards corresponding to level 8 (" Condition of natural resources as a whole, including human health ") ... Levels 1-4 are often considered in particular cases of occupational health, but level 5 is the most suitable category for that purpose. ' The following levels are defined: (I) The health of one man or ofa limited number of men from a simple exposure; (2) the health of one or of several men from limited but repeated exposure; (3) the health of a given proportion of the working population exposed occupationally to certain hazards; (4) the health of random groups of the working population exposed occupationally to health hazards; (5) the health of random groups of working populations not occupationally exposed to health hazards. Forssman (1966)first presented a classification of the biological effects of occupational exposure, distinguishing four categories.
3. Levels of Exposure (A) Safe exposure zone (' no effect' level), (B) Exposure that may induce rapidly reversible effects on health or fitness but that do not cause a definite state of disease; (C) Exposure that may induce reversible disease; (D) Exposure that may induce irreversible disease or death. We could of course agree to set hygiene standards at level(B); however, ergonomic standards concerning air pollution at work must be more strict and cannot exceed , no effect' level (A). In Poland. we have tried for practical purposes to define as a 'contact' cases when the concentration of the chemicals is lower than the maximum allowable concentration (MAC) used in the U.S.S.R.; as 'exposure' when this concentration is higher than the U.S.S.R. MAC but lower than Threshold Limit Values (TLV) approved by the American Conference of Governmental Industrial Hygienists; and as 'danger' when they exceed the American TLV. According to these criteria we have observed changes in some health indices depending upon the situation of the work place. We can say that work in 'contact' with a noxious chemical agent, or even in 'exposure' cases, does not produce any deterioration in health status. We observe quite a different situation if we examine other than chemical noxious agents. Work in conditions fulfilling the' safety standards' of noise, vibration, light, microclimate, and nearly all physical agents (excluding ionizing radiation) can cause
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not only discomfort but also disease. Extra-auditory effects of noise such as neurovegetative reaction, psychological effects and interference with communication have been neglected, to say nothing of the indirect effects of noise, such as annoyance, disturbance, or decrement in performance. In fact, we often observe impairment of hearing at exposure to noise below the accepted level of 85 dB or 90 dB. The proposed ergonomic standard for noise is 65-70 dB. We should adopt a similar approach to standards for occupational exposure to heat. Permissible climatic conditions corresponding to hygiene standards which do not cause health impairment may still involve thermal discomfort and subsequent changes in work performance. Krasucki (1976) described an increased frequency of heart disease among workers in a steel-foundry, resulting from the heat strain over a period of more than twenty years. Optimal climatic conditions which can be recognized as ergonomic standards must provide thermal comfort without overload of the adaptive and thermoregulative functions. Hygiene standards of lighting give an indication of the conditions under which work is possible, but say nothing about visual comfort. Ergonomic investigations of work spaces for small-part assembly have shown that the frequency of impairment of vision and visual defects have decreased proportionally to the improvement of lighting. These considerations lead to the following conclusions: in occupational health surveys we must take into account at least three levels of health risks: (I) work-load (or work-stressors) when environmental factors do not meet hygiene standards; (2) work-load (or work-stressors) when environmental factors meet hygiene standards but fall outside the' comfort zone'; (3) 'No-effect level' when environmental factors are well within the' comfort zone '. 4. The Work-load It should be stressed that work demanding moderate or even high energy expenditure still exists even in modern factories and mechanization, or partial automatization, of operations which change the character of the work does not necessary eliminate the physical load imposed on workers (perhaps because of an increase in auxiliary activities, etc.). Conditions of modern life favour a decrease in physiological adaptability of contemporary men, extending over the entire population. Physical fitness is decreasing, tolerance for changes in the thermal environment is diminishing, and so on. There is an increase in the percentage of older and handicapped workers, having low adaptability. The general term 'heavy work' has doubtful physiological meaning. The same work may be heavy or light-depending on the working capacity of the individual. In every case the relation of work-demand to the subject'S working capacity should be evaluated, both with regard to the work load of healthy young men, and to the work load of elderly or handicapped workers. The criteria of work-load tolerance may differ for each of the above-mentioned groups. Electrocardiographic examination (exercise ECG test and ECG monitoring at the workplace) can be used for individuals with coronary heart disease; repeated measurements of blood glucose for diabetics, etc. (see Taton and Nazar 1977), but the general physiological principles of work tolerance are basically the same in all cases. They require the analysis of work demands and individual workers' capacities.
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It has been established empirically that, in any situation, oxygen consumption (energy expenditure) during work ought not to exceed 50~60 % of the predicted maximal values for workers with a high aerobic capacity, 40-50 % for workers with a moderate capacity, and 30-40% for those with a low capacity. Although physical and physiological demands connected with work and social activities in developed countries are now generally very low, not infrequently they exceed the recommended 30-40 % of maximal capacities. This factor can contribute to the development of excessivefatigue. It is thus not surprising that physical overload resulting not from demands fora high energy expenditure, but from a low physical working capacity, is one cause of the frequently observed chronic fatigue with subsequent health impairment. We must remember that determination of the actual work-load presents some difficulties. The use of alternative methods of workload determination, for example: the evaluation of energy expenditure, shows clearly that different methods may produce completely different results. Methods used for work-description are different and can also give conflicting results. Attempts to produce quantitative estimates of work may, according to Walker-Morris (1976), produce' apparently objective results' but they remain, in fact, subjective opinions. Because of this, the measurement of work-load and workcapacity must be made by the most exact and comparable objective methods. Differences in the physiological strain produced by the same tasks when performed by different workers have been described by Kozlowski (1964) and also by Motyka and Kozlowski (1975). The importance for health of physiologically optimal relationships between physical work requirements and physical capabilities of the worker are even more striking with regard to elderly persons. Working capacity decreases with age (Astrand 1967, 1971). The rate of this decrease is probably independent of the way of life (habitual physical activity level). The slopes of the functions relating physical working capacity to age are very similar for athletes, manual workers, white-collar workers and other active or sedentary people. However, at any age physical working capacity may differ widely, depending upon a person's actual habitual physical activity, or physical activity during his working hours. In any case, the worker pays an increasing physiological cost for performing the same task as he gets older. This is generally true in spite of increasing skill. Although acquired skill and experience are factors facilitating learned performance, they cannot altogether prevent the effects of physiological deterioration with progressing age. A similar problem is found with regard to persons who are chronically disabled, including the increasing number with coronary heart disease, after cardiac surgery, with arterial hypertension, diabetes melitus, chronic pulmonary diseases, etc. The general solution to this problem seems always to be the same: placing physiologically fit men in the appropriate work-place (from the point of view of physiological demands). This is valid for all kinds of occupational activities. In modern industry the demands are changing, but the biology of modern man is also changing. The rate of decrease in physiological work capacities is, in general, probably faster than the real decrease in work demands. Changes in the nature of work demands obviously have to be taken into consideration (changes in information load, in emotional tension etc.). Particular difficulties appear when considering evaluation of static loads, other than health, overstrain and fatigue. This problem, very important in modern industry,
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is still awaiting a solution. Often small ergonomic improvements in the construction of machines or organization of work (changing posture, 'active' breaks etc.) may ameliorate static overstrain of the locomotor system and prevent the development of troubles such as back pains, articular dysfunctions etc. The relationship between physical working capacity and tolerance of heat stress has been described by Kozlowski (1964). The development of thermophysiology and computerized methods for the prediction of thermal stress tolerance can help in preventing health damage among individual workers exposed to extreme conditions of heat and cold in their occupational activities. Finally, there is the extremely difficult problem of quantification and evaluation of emotional stress among professional groups, from the point of view of health hazards. Recent achievements by Levi, Frankenhauser, and others (see Frankenhauser 1977) provide new insights into bodily changes under conditions of both 'information underload' and 'information overload', as well as into the effects of other influences of work itself and its milieu, primarily exerted at the level of the central nervous system. Summarizing: automatization of physiological measurements and computerized processing of the data so obtained, permit repeated and precise evaluation of physical status-including parameters of working capacity-of people employed at different workplaces. The results have to be compared with the physiological demands of working activities. This should be the basis for the answer to the crucial question: are. capabilities related to demands or not? From the point of view of workers' general health problems, physiological and psychophysiological overstrain still retain their crucial position. The pattern and, possibly, mechanisms of overstrain are changing, but the basic concept is still valid. . Ergonomics has to contribute to the prevention of this physiological and psychophysiological overstrain.
5. Well-being and Job Satisfaction We have so far described ergonomic criteria related to physical health. Problems connected with mental and social health and with well-being raise many more difficulties. As Guillot (1977) quite rightly emphasized, if work is only a harsh necessity we have many reasons for absence from work, but for presence only two: someone may like his job-and this is an important reason for many occupations; however, and this is the second case, men are generally working under economic pressure. During the last thirty years we have observed an evolution in the man-work relation. Many specialists have presented data showing that certain kinds of work are unsatisfactory in spite of wages or salaries. Let me cite one example: Franzen (1974) presented a situation in the Granges Steel Plant where work was evaluated by the workers as 'too heavy'. Sickness absence rates reached 10% and turnover rates 14%. After implementing many expensive programmes including several changes in work organization, work-methods and social policy, absenteeism dropped to 6%; turnover to 7 %; thus, all these measures were evidently worth while. As Aberg (1977) has noted: •The general tendency is now not only to improve the working environment in order to reduce work hazards, but to achieve comfort conditions at work. How do we define good working conditions? It is obvious that we are talking about a multidimensionality including physical, physiological, as well as
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psychological reprievements '. All these conditions should be established at a comfort level. Carpentier (1977) includes in social factors, inter alia, the need for participation in management decisions and the possibilities which result from a development of the social infrastructure in its broadest sense. He emphasizes that implementing ergonomic principles can contribute on important part of the improvement of 'work-life' with regard to its social or psychological aspects. This opinion is confirmed by results of a study undertaken in a Polish Steelworks. In answer to the question: 'Do you want-in the future-to see your son at your work-place? '-nearly 90% of the workers said: 'No, I don't! '. In such cases we certainly cannot speak of' job satisfaction' among the investigated population. This lack of job satisfaction was connected with high indices of labour turnover and sickness absenteeism (Krasucki, 1977). According to suggestions resulting from the above-mentioned study, from" the ergonomic point of view we ought to use the following indices when evaluating work places: (a) the environmental stress (noise, vibration, temperature, air constraints) may exceed the maximal allowable levels, taking into account the above-mentioned comfort zone; (b) the work organization and/or the work methods can be the cause of physical or mental stress; (c) the workers' health as a whole, or from certain specificpoints of view, may be worse than that found for similar sex and age groups working elsewhere; (d) the working methods and conditions may be unacceptable to the workers and consequently there is a high labour turnover. Looking into questions concerning the use of ergonomic criteria in public health surveys, we should remember that the crux of the matter is that all imaginable criteria are less well-defined than in occupational medicine. An Expert Committee of the World Health Organization has suggested the following twelve' health conditions' : l. Health status (including demographic data). 2. Food and nutrition. 3. Educational level. 4. Working conditions. 5. Employment. 6. Collective consumption and saving. 7. Transport and communication. 8. Housing. 9. Clothing. 10. Leisure and recreation. II. Social security system. 12. Civil rights and liberties. These factors influence the health status of every society and also particular groups and individuals. Leowski (1978) has indicated that although we can obtain a kind of feed-back between these factors and health, we cannot use them as healthindices. For example, a study made in a Warsaw factory in 1967has shown that working women were more tired at the beginning of the work than when they had finished the first shift. The irregularity of various public transport services, connected with strictly ERG.
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enforced disciplinary measures for being late at work, produced symptoms of strain. Of course, an improvement in the transport system should eliminate these indirect influences on the health-status of the workers. Brown (1954) has stated that: 'We must concern ourselves with the following questions: '(I) What is the nature of man as an individual and what, if any, are his basic needs? . (2) What is the nature of man as a social animal and how does he relate himself to society?' These questions are still very real. Many proposals concerning the hierarchy of human needs, for example the one proposed by Maslow (1954), are only arbitrary approximations. . Data published by the U.S. Department of Health, Education and Welfare regarding the health-status of American society refer, among other factors, to 'restricted activity'. This may equally probably be caused by low physical fitness or by mental or social discomfort. It seems possible to eliminate or reduce some causes of all kinds of discomfort. In such an undertaking, methods used in ergonomics may be helpful. Perhaps for this reason, in recent years the extension of the notion of ergonomics and the connection between ergonomics and life conditions have become two of the more frequently discussed problems. Chapanis (1977), Parmeggiani (1977), Rosner (1978), and other specialists, have asked for the inclusion in ergonomic surveys of aspects belonging traditionally to sociology. These concern not only job satisfaction, but also life satisfaction. Because these factors are elements of mental and social well-being, improvement of health-status has to include the evaluation of the social status of each individual. The main problem is: how to measure health conditions? In spite of all the difficulties, an answer to this question is necessary if we want to use ergonomics in public health surveys. There is no doubt that we cannot use one single scheme in surveys concerning various people, or various groups. It is clear that the desirable conditions are different, depending on a variety of factors. For general cultural reasons, the notion of' comfort' must be fixed differently and independently for each investigated group. Obviously this does not refer to such factors as nutrition or working conditions, in relation to which we have more or less agreed' standards'. But, apart from these cases, we should try to find for every single factor the dose-effect relation measured, for example, by some specified psychological technique. This procedure should enable us to establish the dose-response relation in the investigated populations. Knowing the participation of each factor in our own evaluation of the life conditions, we can begin to think of improving the existing situation. Although it seems at present unrealistic to establish general principles for such factors as leisure and recreation, collective consumption, or civil rights; and although, according to Pascal, something may look good on this side of the river and bad on the other; we must search for solutions. Mere generalization will lead to errors and mistakes. The general conclusion is that public health surveys should be based on an exact knowledge of the social anthropology of the investigated population. This is particu-
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larly important in developing countries. If we want to use ergonomics for occupational and public health surveys, the first step is to determine the zones of comfort for all analysed factors and all investigated groups. This implies the creation of teams able to prepare a programme for such researches. We can expect some astonishing results from such an investigation, an adaptation of existing life conditions to the needs, requirements, or dreams of mankind should be our final aim. But it is likely that we shall have to decide to what extent we are allowed to make somebody happy, according to his own conception of happiness. It is easier to make men happy according to our own conceptions. We can produce, using educational systems, mass-media and even official opinion or pressure, an army of' Unknown Citizens'; to use an expression from a poem of W. H. Auden, Nobody knows to what future our' trials and tribulations' will lead us. But that is another story. References ABERG, V., 1977, In: Ergonomics in Industry, Agriculture and Forestry (Geneva). I.. 1967. Ergonomics, 10. ASTRAND. I.. 1971, Amer. J. Clin. Nutr., 24. BROWN. J. A, C.. 1954. Social Psychology in Industry, London.
ASTRAND.
CARPENTIER, A .. 1977. In: Ergonomics in Industrv. Agriculture and Forestry. (Geneva). CHAPANIS, A .. 1977, In: Ergonomics in Industry, Agriculture and Forestry, (Geneva).
DAVIES. C. T. M.. 1973. Brit. J. Ind. Med.• 30. FORSSMAN. S.• 1955. Bull. WHO. 13. FORSSMAN. S.• 1966. Proe. of the XV Intern. Congress ace. Hlth .. (Vienna). FORTUIN, G.1 .• 1955. Bull WHO. 13. FRANKENHAUSER, M .. 1977. In: Society. Stress and Disease, (Oxford). FRANK. V. E., 1975, The Unconscious Goal, (New York). FRANZEN. A. 8., 1974, Paper in Intern. Symp. on Ergonomics, (Bucharest). GADOUREK. I., 1965. Absence and Well-being of Workers. (Assen). GUILLOT, J., 1977, In: Ergonomics in Industry, Agriculture and Forestry, (Geneva). HINKLE, L. E., and PLUMMER. N.• 1965. In: Philosophy and Science of Public Health. (London). INDULSKI.1 .. 1965. Biul. WAM, Suppl. 20. KOZLOWSKI, S.• and SALTIN, B., 1964. Journ, appl. Phys., 19. KRASUCKI. P., 1976, La Sante Publioue, I. KRASUCKI. P., 1977. Ergonomics in Industry, Agriculture and Forestry. (Geneva). KRICHAGIN. V. I.. 1977, Health and Environment, 8. LEOWSKI,1.. 1978. Report on Health and Health-related Indicators. LOKANDER. S.. 1962, Acta Med. Scand., Suppl. 377. MASLOW. A. H .• 1954, Motivation and Personality, (New York). MONOD. H .. and LILLE. F.. 1966. Arch. Molad. Prof Med. Prev, Soc.. 37. MOTVKA. K .• and KOZLOWSKI. S.• 1975. Normal values of pulmonary and circulatory adaptation during graded physical exercise and relation to age and sex. Population study. Special Report. (Warszaw). PARMEGGIANI. L.. 1977, In: Ergonomics in Industry. Agriculture and Forestry, (Geneva). ROSNER, J., 1978. Ergonomia, 1. SANDERS. B. S.. 1964. Amer. J. Publ, Hlth .. 54. SANOTZKY, W. N., 1970. In: Permissible Levels of Toxic Substances, (Geneva). SELIKOFF. I. 1., 1972, In: Safety and Health in Shipbuilding, (Geneva). SHEPHARD, R. D .• and Walker. 1., 1957. Brit. Journ, Ind. Med.. 4. SIGERIST. H. E.. 1941. Medicine and Human Welfare. (Newhaven). STOCKINGER, H.. 1970, In: Permissible Levels of Toxic Substances, (Geneva). SmuMAN. K .. and FALK. 1. S., 1936. Bull-.Hlth Org. League oj Nations,S. WALKER-MoRRIS. 1.• 1973, Principles and Practice oj Job Evaluation. 1973. (London). VROOM. V. H .• 1964, Work and Motivation, (New York). THUS-EvESE"', E., 1957. Proc. of the XII Congr, Occ. Hlth., (Helsinki). TRUHAUT, R .. 1970. In: Permissible Levels of Toxic Substances, (Geneva). TAVLOR, P. J .• 1968, ace. Med.• 18. WHO Technical Report Series No. 574, Geneva 1975. WHO Technical Report Series No. 601. Geneva 1977. TATON, 1., and NAZAR. K .. 1977 Koerperliche LeistungfaehigkeiI und Diabetes Mellitus. (Stuttgart).
ISSN: 0014-0139 (Print) 1366-5847 (Online) Journal homepage: http://www.tandfonline.com/loi/terg20
Ergonomics and Occupational and Public Health Surveys STANISLAW KOZLOWSKI & PIOTR KRASUCKI To cite this article: STANISLAW KOZLOWSKI & PIOTR KRASUCKI (1979) Ergonomics and Occupational and Public Health Surveys, Ergonomics, 22:6, 651-659, DOI: 10.1080/00140137908924650 To link to this article: http://dx.doi.org/10.1080/00140137908924650
Published online: 27 Mar 2007.
Submit your article to this journal
Article views: 16
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=terg20 Download by: [Universite Laval]
Date: 07 November 2015, At: 00:42
ERGONOMICS, 1979, VOL. 22, No.6, 651-659
Ergonomics and Occupational and Public Health Surveys By STANISLAW KOZLOWSKI and PIOTR KRASUCKI Warsaw. Poland Hygiene standards used in occupational medicine were created for health protection. How-
Downloaded by [Universite Laval] at 00:42 07 November 2015
ever. there is apparently no agreement as to what is health and how it can be measured. This
paper reviews the various criteria for health, used in the past 15-20 years; it evaluates approaches which attempt classifications of exposure to risk via levels of reversible and irreversible disease; it criticizes methods used for work-description; and supports procedures for establishing dose-effect and dose-response relationships in specific work situations. The general conclusion is that public health surveys should be based on exact knowledge of the social anthropology of the investigated population, which determines acceptable . comfort zones' for all life conditions. Ergonomie Appliquee aux Enquires de Medecine du Travail el de Sante Publique. Ergonomie fUr Berufliche und OjJentliche Gesundheitsiiberwachungen
1. Introduction The aim of occupational and public health surveys is first and foremost to find the factors which are responsible for changes in the health status and well-being of the population. Generally, in these surveys, we can use methods developed for epidemiological studies. We have to select a population which will be examined and divide it into groups' exposed' and' not exposed' to a risk, according to the relationship between the factors which are the object of our research-and the real situation of persons in the investigated population. This is a very simple process if we are studying factors such as sex, age, marital status, or profession, because in these cases we have unmistakable criteria: someone is a man or a woman; he is above or below a predetermined age criterion; he may have one child or two children; and so on. But problems arise if we want to subdivide the population using, for example, criteria connected with physiological or hygiene standards.
2. Criteria of Health Hygiene standards used in occupational medicine were created for health protection. But we have no agreement as to what is 'health' and how it can be measured. The variety of health indices proposed from the time of Stouman and Falk (1936) until the present day is a sure sign that wehave no 'ideal' index of health. The definition recommended by the World Health Organization and based on a former proposition ofSigerist (1941) takes into account not only the absence of disease but, also the individual's physical, mental and social well-being. The suggestion of Sigerist was that health' is something positive, ajoyful attitude toward life and cheerful acceptance of the responsibility that life puts on the individual'. In a review of methods of health measurement published by Sanders (1964), it is proposed that they should take into account the' functional adequacy of an individual to fulfil the role which a healthy member of his age and sex is expected to fulfil in his society'. 0014-0139/79/220f> 0651 $02.00
© 1979 Taylor and Francis Ltd.
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We can extend this definition to include Frankl's (1975) theory, which stresses that an indispensable condition of health is to have a 'will to meaning', or 'purpose in life', because the lack of it leads to psychosocial disturbances. However, in practice we have to apply a simpler criterion of health. Thus, health indicators described by Leowski (1978) are divided into: indicators connected with life expectancy and mortality rate; indicators of morbidity and disability; and socalled indicators of positive health. This last group of indicators is used for the evaluation of health status of the newborn and children; because its' standards' with regard to adults are uncertain. The choice of health indices depends upon the kind of epidemiological methods used. In retrospective studies we can use mortality statistics as shown by Selikoff (1972) in his study of asbestos dust and cancer. In prospective studies we must use indirect indices, such as the analysis of sickness absenteeism and the number of visits to the doctor. Although Taylor (1968) described cases which he termed' resistant', where sickness absenteeism occurred regardless of health status, these are only isolated incidences. For commonly used methods of analysis, these indirect indices are usually sufficiently accurate. In many publications we can find results of investigations based on such indices: for example Thiis-Evesen (1957) has studied the relation between morbidity and shift-work; Shephard and Walker (1957) looked at absenteeism and work-load; and Forssman (1955), Fortuin (1955), Indulski (1965), Krasucki (1976), and Lokander (1962) have analysed many other social and environmental factors in relation to sickness absence level. In the past few years (WHO 1975and 1977)two new terms have been introduced: (I) the dose (uptake)-effecl relationship; indicating the relation between the uptake of a chemical and the magnitude of a qualitatively specified affect on an individual, (2) the dose (uptake)-response relationship; indicating the relation between the uptake of a chemical and the proportion of individuals with a quantitatively specified magnitude of a qualitatively specified effect in a group of subjects. We can now estimate the degree of toxicity of chemically harmful agents. We have an idea of the standardization of methods used in establishing permissible levels in occupational exposure to harmful agents. Based upon data such as qualitative biological effects (e.g. decreased blood haemoglobin concentrations, or impaired psychomotor performance) and the intensity of some of these effects, or the proportion of subjects affected, we can describe various levels of the dose-effect relationship and also of the dose-response relationship. The measurement of the impairment of physical health in relation to the uptake or dose is relatively easy with regard to chemically harmful agents and industrial dusts. We can record continuously the concentration of these agents in the air, and we can estimate their absorption. We must remember, however, that the uptake of chemicals or dusts depends not only on their concentration, but also on factors such as: body size, the respiratory minute volume expenditure required by the workload and by the barometric pressure, the duration of work in given conditions, etc. Also significant may be the compound physico-chemical characteristics which determine its pharmaco-kinetic fate, the proportion of the respirable fraction andlast but not least-individual or group differences in reaction, due to such factors as genetic traits, nutritional status and others. Because of these differences, Truhaut (1970) suggested that 'maximum tolerable concentrations represent average concentration to which workers may be exposed during the eight hours of their working
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day-excluding cases of hypersensitivity'. In addition, Stockinger (1970) suggests that hypersusceptible workers ought to be excluded from analyses of the uptake: effect relation. Sanotzky (1970) defined maximum allowable concentrations as 'concentrations that, by their action on exposure of the human body, periodically or throughout life, directly or indirectly, will not cause the development of physical or mental disease including latent or temporarily compensated conditions or changes in the state of health that go beyond the limits of adaptive responses detectable by modern methods of investigation, either immediately or in the long term in this or in subsequent generations' . In spite of these demands, Krichagin (1977), dealing with protection categories on eight levels writes: 'The ideal goal of health authorities is to obtain protection standards corresponding to level 8 (" Condition of natural resources as a whole, including human health ") ... Levels 1-4 are often considered in particular cases of occupational health, but level 5 is the most suitable category for that purpose. ' The following levels are defined: (I) The health of one man or ofa limited number of men from a simple exposure; (2) the health of one or of several men from limited but repeated exposure; (3) the health of a given proportion of the working population exposed occupationally to certain hazards; (4) the health of random groups of the working population exposed occupationally to health hazards; (5) the health of random groups of working populations not occupationally exposed to health hazards. Forssman (1966)first presented a classification of the biological effects of occupational exposure, distinguishing four categories.
3. Levels of Exposure (A) Safe exposure zone (' no effect' level), (B) Exposure that may induce rapidly reversible effects on health or fitness but that do not cause a definite state of disease; (C) Exposure that may induce reversible disease; (D) Exposure that may induce irreversible disease or death. We could of course agree to set hygiene standards at level(B); however, ergonomic standards concerning air pollution at work must be more strict and cannot exceed , no effect' level (A). In Poland. we have tried for practical purposes to define as a 'contact' cases when the concentration of the chemicals is lower than the maximum allowable concentration (MAC) used in the U.S.S.R.; as 'exposure' when this concentration is higher than the U.S.S.R. MAC but lower than Threshold Limit Values (TLV) approved by the American Conference of Governmental Industrial Hygienists; and as 'danger' when they exceed the American TLV. According to these criteria we have observed changes in some health indices depending upon the situation of the work place. We can say that work in 'contact' with a noxious chemical agent, or even in 'exposure' cases, does not produce any deterioration in health status. We observe quite a different situation if we examine other than chemical noxious agents. Work in conditions fulfilling the' safety standards' of noise, vibration, light, microclimate, and nearly all physical agents (excluding ionizing radiation) can cause
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not only discomfort but also disease. Extra-auditory effects of noise such as neurovegetative reaction, psychological effects and interference with communication have been neglected, to say nothing of the indirect effects of noise, such as annoyance, disturbance, or decrement in performance. In fact, we often observe impairment of hearing at exposure to noise below the accepted level of 85 dB or 90 dB. The proposed ergonomic standard for noise is 65-70 dB. We should adopt a similar approach to standards for occupational exposure to heat. Permissible climatic conditions corresponding to hygiene standards which do not cause health impairment may still involve thermal discomfort and subsequent changes in work performance. Krasucki (1976) described an increased frequency of heart disease among workers in a steel-foundry, resulting from the heat strain over a period of more than twenty years. Optimal climatic conditions which can be recognized as ergonomic standards must provide thermal comfort without overload of the adaptive and thermoregulative functions. Hygiene standards of lighting give an indication of the conditions under which work is possible, but say nothing about visual comfort. Ergonomic investigations of work spaces for small-part assembly have shown that the frequency of impairment of vision and visual defects have decreased proportionally to the improvement of lighting. These considerations lead to the following conclusions: in occupational health surveys we must take into account at least three levels of health risks: (I) work-load (or work-stressors) when environmental factors do not meet hygiene standards; (2) work-load (or work-stressors) when environmental factors meet hygiene standards but fall outside the' comfort zone'; (3) 'No-effect level' when environmental factors are well within the' comfort zone '. 4. The Work-load It should be stressed that work demanding moderate or even high energy expenditure still exists even in modern factories and mechanization, or partial automatization, of operations which change the character of the work does not necessary eliminate the physical load imposed on workers (perhaps because of an increase in auxiliary activities, etc.). Conditions of modern life favour a decrease in physiological adaptability of contemporary men, extending over the entire population. Physical fitness is decreasing, tolerance for changes in the thermal environment is diminishing, and so on. There is an increase in the percentage of older and handicapped workers, having low adaptability. The general term 'heavy work' has doubtful physiological meaning. The same work may be heavy or light-depending on the working capacity of the individual. In every case the relation of work-demand to the subject'S working capacity should be evaluated, both with regard to the work load of healthy young men, and to the work load of elderly or handicapped workers. The criteria of work-load tolerance may differ for each of the above-mentioned groups. Electrocardiographic examination (exercise ECG test and ECG monitoring at the workplace) can be used for individuals with coronary heart disease; repeated measurements of blood glucose for diabetics, etc. (see Taton and Nazar 1977), but the general physiological principles of work tolerance are basically the same in all cases. They require the analysis of work demands and individual workers' capacities.
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It has been established empirically that, in any situation, oxygen consumption (energy expenditure) during work ought not to exceed 50~60 % of the predicted maximal values for workers with a high aerobic capacity, 40-50 % for workers with a moderate capacity, and 30-40% for those with a low capacity. Although physical and physiological demands connected with work and social activities in developed countries are now generally very low, not infrequently they exceed the recommended 30-40 % of maximal capacities. This factor can contribute to the development of excessivefatigue. It is thus not surprising that physical overload resulting not from demands fora high energy expenditure, but from a low physical working capacity, is one cause of the frequently observed chronic fatigue with subsequent health impairment. We must remember that determination of the actual work-load presents some difficulties. The use of alternative methods of workload determination, for example: the evaluation of energy expenditure, shows clearly that different methods may produce completely different results. Methods used for work-description are different and can also give conflicting results. Attempts to produce quantitative estimates of work may, according to Walker-Morris (1976), produce' apparently objective results' but they remain, in fact, subjective opinions. Because of this, the measurement of work-load and workcapacity must be made by the most exact and comparable objective methods. Differences in the physiological strain produced by the same tasks when performed by different workers have been described by Kozlowski (1964) and also by Motyka and Kozlowski (1975). The importance for health of physiologically optimal relationships between physical work requirements and physical capabilities of the worker are even more striking with regard to elderly persons. Working capacity decreases with age (Astrand 1967, 1971). The rate of this decrease is probably independent of the way of life (habitual physical activity level). The slopes of the functions relating physical working capacity to age are very similar for athletes, manual workers, white-collar workers and other active or sedentary people. However, at any age physical working capacity may differ widely, depending upon a person's actual habitual physical activity, or physical activity during his working hours. In any case, the worker pays an increasing physiological cost for performing the same task as he gets older. This is generally true in spite of increasing skill. Although acquired skill and experience are factors facilitating learned performance, they cannot altogether prevent the effects of physiological deterioration with progressing age. A similar problem is found with regard to persons who are chronically disabled, including the increasing number with coronary heart disease, after cardiac surgery, with arterial hypertension, diabetes melitus, chronic pulmonary diseases, etc. The general solution to this problem seems always to be the same: placing physiologically fit men in the appropriate work-place (from the point of view of physiological demands). This is valid for all kinds of occupational activities. In modern industry the demands are changing, but the biology of modern man is also changing. The rate of decrease in physiological work capacities is, in general, probably faster than the real decrease in work demands. Changes in the nature of work demands obviously have to be taken into consideration (changes in information load, in emotional tension etc.). Particular difficulties appear when considering evaluation of static loads, other than health, overstrain and fatigue. This problem, very important in modern industry,
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is still awaiting a solution. Often small ergonomic improvements in the construction of machines or organization of work (changing posture, 'active' breaks etc.) may ameliorate static overstrain of the locomotor system and prevent the development of troubles such as back pains, articular dysfunctions etc. The relationship between physical working capacity and tolerance of heat stress has been described by Kozlowski (1964). The development of thermophysiology and computerized methods for the prediction of thermal stress tolerance can help in preventing health damage among individual workers exposed to extreme conditions of heat and cold in their occupational activities. Finally, there is the extremely difficult problem of quantification and evaluation of emotional stress among professional groups, from the point of view of health hazards. Recent achievements by Levi, Frankenhauser, and others (see Frankenhauser 1977) provide new insights into bodily changes under conditions of both 'information underload' and 'information overload', as well as into the effects of other influences of work itself and its milieu, primarily exerted at the level of the central nervous system. Summarizing: automatization of physiological measurements and computerized processing of the data so obtained, permit repeated and precise evaluation of physical status-including parameters of working capacity-of people employed at different workplaces. The results have to be compared with the physiological demands of working activities. This should be the basis for the answer to the crucial question: are. capabilities related to demands or not? From the point of view of workers' general health problems, physiological and psychophysiological overstrain still retain their crucial position. The pattern and, possibly, mechanisms of overstrain are changing, but the basic concept is still valid. . Ergonomics has to contribute to the prevention of this physiological and psychophysiological overstrain.
5. Well-being and Job Satisfaction We have so far described ergonomic criteria related to physical health. Problems connected with mental and social health and with well-being raise many more difficulties. As Guillot (1977) quite rightly emphasized, if work is only a harsh necessity we have many reasons for absence from work, but for presence only two: someone may like his job-and this is an important reason for many occupations; however, and this is the second case, men are generally working under economic pressure. During the last thirty years we have observed an evolution in the man-work relation. Many specialists have presented data showing that certain kinds of work are unsatisfactory in spite of wages or salaries. Let me cite one example: Franzen (1974) presented a situation in the Granges Steel Plant where work was evaluated by the workers as 'too heavy'. Sickness absence rates reached 10% and turnover rates 14%. After implementing many expensive programmes including several changes in work organization, work-methods and social policy, absenteeism dropped to 6%; turnover to 7 %; thus, all these measures were evidently worth while. As Aberg (1977) has noted: •The general tendency is now not only to improve the working environment in order to reduce work hazards, but to achieve comfort conditions at work. How do we define good working conditions? It is obvious that we are talking about a multidimensionality including physical, physiological, as well as
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psychological reprievements '. All these conditions should be established at a comfort level. Carpentier (1977) includes in social factors, inter alia, the need for participation in management decisions and the possibilities which result from a development of the social infrastructure in its broadest sense. He emphasizes that implementing ergonomic principles can contribute on important part of the improvement of 'work-life' with regard to its social or psychological aspects. This opinion is confirmed by results of a study undertaken in a Polish Steelworks. In answer to the question: 'Do you want-in the future-to see your son at your work-place? '-nearly 90% of the workers said: 'No, I don't! '. In such cases we certainly cannot speak of' job satisfaction' among the investigated population. This lack of job satisfaction was connected with high indices of labour turnover and sickness absenteeism (Krasucki, 1977). According to suggestions resulting from the above-mentioned study, from" the ergonomic point of view we ought to use the following indices when evaluating work places: (a) the environmental stress (noise, vibration, temperature, air constraints) may exceed the maximal allowable levels, taking into account the above-mentioned comfort zone; (b) the work organization and/or the work methods can be the cause of physical or mental stress; (c) the workers' health as a whole, or from certain specificpoints of view, may be worse than that found for similar sex and age groups working elsewhere; (d) the working methods and conditions may be unacceptable to the workers and consequently there is a high labour turnover. Looking into questions concerning the use of ergonomic criteria in public health surveys, we should remember that the crux of the matter is that all imaginable criteria are less well-defined than in occupational medicine. An Expert Committee of the World Health Organization has suggested the following twelve' health conditions' : l. Health status (including demographic data). 2. Food and nutrition. 3. Educational level. 4. Working conditions. 5. Employment. 6. Collective consumption and saving. 7. Transport and communication. 8. Housing. 9. Clothing. 10. Leisure and recreation. II. Social security system. 12. Civil rights and liberties. These factors influence the health status of every society and also particular groups and individuals. Leowski (1978) has indicated that although we can obtain a kind of feed-back between these factors and health, we cannot use them as healthindices. For example, a study made in a Warsaw factory in 1967has shown that working women were more tired at the beginning of the work than when they had finished the first shift. The irregularity of various public transport services, connected with strictly ERG.
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enforced disciplinary measures for being late at work, produced symptoms of strain. Of course, an improvement in the transport system should eliminate these indirect influences on the health-status of the workers. Brown (1954) has stated that: 'We must concern ourselves with the following questions: '(I) What is the nature of man as an individual and what, if any, are his basic needs? . (2) What is the nature of man as a social animal and how does he relate himself to society?' These questions are still very real. Many proposals concerning the hierarchy of human needs, for example the one proposed by Maslow (1954), are only arbitrary approximations. . Data published by the U.S. Department of Health, Education and Welfare regarding the health-status of American society refer, among other factors, to 'restricted activity'. This may equally probably be caused by low physical fitness or by mental or social discomfort. It seems possible to eliminate or reduce some causes of all kinds of discomfort. In such an undertaking, methods used in ergonomics may be helpful. Perhaps for this reason, in recent years the extension of the notion of ergonomics and the connection between ergonomics and life conditions have become two of the more frequently discussed problems. Chapanis (1977), Parmeggiani (1977), Rosner (1978), and other specialists, have asked for the inclusion in ergonomic surveys of aspects belonging traditionally to sociology. These concern not only job satisfaction, but also life satisfaction. Because these factors are elements of mental and social well-being, improvement of health-status has to include the evaluation of the social status of each individual. The main problem is: how to measure health conditions? In spite of all the difficulties, an answer to this question is necessary if we want to use ergonomics in public health surveys. There is no doubt that we cannot use one single scheme in surveys concerning various people, or various groups. It is clear that the desirable conditions are different, depending on a variety of factors. For general cultural reasons, the notion of' comfort' must be fixed differently and independently for each investigated group. Obviously this does not refer to such factors as nutrition or working conditions, in relation to which we have more or less agreed' standards'. But, apart from these cases, we should try to find for every single factor the dose-effect relation measured, for example, by some specified psychological technique. This procedure should enable us to establish the dose-response relation in the investigated populations. Knowing the participation of each factor in our own evaluation of the life conditions, we can begin to think of improving the existing situation. Although it seems at present unrealistic to establish general principles for such factors as leisure and recreation, collective consumption, or civil rights; and although, according to Pascal, something may look good on this side of the river and bad on the other; we must search for solutions. Mere generalization will lead to errors and mistakes. The general conclusion is that public health surveys should be based on an exact knowledge of the social anthropology of the investigated population. This is particu-
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larly important in developing countries. If we want to use ergonomics for occupational and public health surveys, the first step is to determine the zones of comfort for all analysed factors and all investigated groups. This implies the creation of teams able to prepare a programme for such researches. We can expect some astonishing results from such an investigation, an adaptation of existing life conditions to the needs, requirements, or dreams of mankind should be our final aim. But it is likely that we shall have to decide to what extent we are allowed to make somebody happy, according to his own conception of happiness. It is easier to make men happy according to our own conceptions. We can produce, using educational systems, mass-media and even official opinion or pressure, an army of' Unknown Citizens'; to use an expression from a poem of W. H. Auden, Nobody knows to what future our' trials and tribulations' will lead us. But that is another story. References ABERG, V., 1977, In: Ergonomics in Industry, Agriculture and Forestry (Geneva). I.. 1967. Ergonomics, 10. ASTRAND. I.. 1971, Amer. J. Clin. Nutr., 24. BROWN. J. A, C.. 1954. Social Psychology in Industry, London.
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CARPENTIER, A .. 1977. In: Ergonomics in Industrv. Agriculture and Forestry. (Geneva). CHAPANIS, A .. 1977, In: Ergonomics in Industry, Agriculture and Forestry, (Geneva).
DAVIES. C. T. M.. 1973. Brit. J. Ind. Med.• 30. FORSSMAN. S.• 1955. Bull. WHO. 13. FORSSMAN. S.• 1966. Proe. of the XV Intern. Congress ace. Hlth .. (Vienna). FORTUIN, G.1 .• 1955. Bull WHO. 13. FRANKENHAUSER, M .. 1977. In: Society. Stress and Disease, (Oxford). FRANK. V. E., 1975, The Unconscious Goal, (New York). FRANZEN. A. 8., 1974, Paper in Intern. Symp. on Ergonomics, (Bucharest). GADOUREK. I., 1965. Absence and Well-being of Workers. (Assen). GUILLOT, J., 1977, In: Ergonomics in Industry, Agriculture and Forestry, (Geneva). HINKLE, L. E., and PLUMMER. N.• 1965. In: Philosophy and Science of Public Health. (London). INDULSKI.1 .. 1965. Biul. WAM, Suppl. 20. KOZLOWSKI, S.• and SALTIN, B., 1964. Journ, appl. Phys., 19. KRASUCKI. P., 1976, La Sante Publioue, I. KRASUCKI. P., 1977. Ergonomics in Industry, Agriculture and Forestry. (Geneva). KRICHAGIN. V. I.. 1977, Health and Environment, 8. LEOWSKI,1.. 1978. Report on Health and Health-related Indicators. LOKANDER. S.. 1962, Acta Med. Scand., Suppl. 377. MASLOW. A. H .• 1954, Motivation and Personality, (New York). MONOD. H .. and LILLE. F.. 1966. Arch. Molad. Prof Med. Prev, Soc.. 37. MOTVKA. K .• and KOZLOWSKI. S.• 1975. Normal values of pulmonary and circulatory adaptation during graded physical exercise and relation to age and sex. Population study. Special Report. (Warszaw). PARMEGGIANI. L.. 1977, In: Ergonomics in Industry. Agriculture and Forestry, (Geneva). ROSNER, J., 1978. Ergonomia, 1. SANDERS. B. S.. 1964. Amer. J. Publ, Hlth .. 54. SANOTZKY, W. N., 1970. In: Permissible Levels of Toxic Substances, (Geneva). SELIKOFF. I. 1., 1972, In: Safety and Health in Shipbuilding, (Geneva). SHEPHARD, R. D .• and Walker. 1., 1957. Brit. Journ, Ind. Med.. 4. SIGERIST. H. E.. 1941. Medicine and Human Welfare. (Newhaven). STOCKINGER, H.. 1970, In: Permissible Levels of Toxic Substances, (Geneva). SmuMAN. K .. and FALK. 1. S., 1936. Bull-.Hlth Org. League oj Nations,S. WALKER-MoRRIS. 1.• 1973, Principles and Practice oj Job Evaluation. 1973. (London). VROOM. V. H .• 1964, Work and Motivation, (New York). THUS-EvESE"', E., 1957. Proc. of the XII Congr, Occ. Hlth., (Helsinki). TRUHAUT, R .. 1970. In: Permissible Levels of Toxic Substances, (Geneva). TAVLOR, P. J .• 1968, ace. Med.• 18. WHO Technical Report Series No. 574, Geneva 1975. WHO Technical Report Series No. 601. Geneva 1977. TATON, 1., and NAZAR. K .. 1977 Koerperliche LeistungfaehigkeiI und Diabetes Mellitus. (Stuttgart).
