Millions of man-hours are lost to industry through employees suffering backache or strain caused by operating poorly designed machines and vehicles or moving awkward and heavy loads．Production is also interrupted by injury from other causes，such as vibration and excessive noise．
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But help is coming from a perhaps unexpected quarter for companies prepared to plan their workshops and manufacturing lines to take account of these hazards．
The necessary information is emerging from a recently formed team of Ministry of Defense scientists at the Army Personnel Research Establishment at Farnborough．They are measuring factors which limit a soldier’s ability to cope with advanced technical equipment and new types of vehicles，or to carry out routine jobs under difficult working conditions．
The problems of the factory and office manager may at first sight seem distant from those of the Army．
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A task force of 120 physiologists，biologists，computer scientists，technologists and soldiers is therefore looking for the point at which human factors set the limit to the use of technology．
It is the stage at which no matter how advanced the engineering，it is the man who caused the complicated equipment to fail．
Dr．John Nelms，director of the establishment，says：“In an era when there is almost nothing the engineer can not build，man is the limiting factor．The research program marks a new stage in the evolution of the army in looking at how best to make the soldier and technology compatible．If we do not get the relationship fight，the next battiefield could be a shambles．”
To meet the vast range of occupational hazards faced by the armed forces，the research group is measuring the limits imposed by physical stress arising from heat and cold，noise and vibration，psychological pressure，and the operational stress of putting high technology system into battleground conditions．The army also has an obligation during peacetime and training exercises to ensure that its men are exposed to greater risks to，say，hearing than those encountered in a well-run industry．
Trials to discover how stress cuts the efficiency of a man with a guided missile or a new tank electronic control and firing system，perhaps by reducing his“hit rate”from 100 percent to only 50，may appear to be a special requirement．But it is also relevant to the introduction in industry and commerce of new technologies with keyboard controls and visual displays．
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Different patterns of noise are measured at Farnborough because damage to hearing is produced in various ways．Impulse noise from gunfire produces high pressures on the ear of a short duration，making the effects on the ear difficult to measure．
For instance，a rifle shot produces a maximum pressure of l60 decibels，lasting less than a hundredth of a second，at the ear of the marksman，whereas a typical industrial noise might reach an average level of 90 decibels over most of the working day．Some idea of those noise levels is given by what a person hears about 20 feet from a roadway—from motorcycles it is 89 decibels，cars 87 decibels，light commercial vehicles 88 and heavy lorries 92．
The effect on the body of lifting，loading and carrying objects is perhaps the work that has the widest common application to industry and the Army．
But the methods used today by the research team and the trials section—a group of regular soldiers seconded for two years for this work—to measure physiological limitations imposed by physical stress and strain are far from usual．
The measurements involve monitoring muscle fatigue by analyzing the bioelectric signals produced during movement and examination of the energy being expended and the muscle strength．
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Particular tasks scrutinized at Farnborough include such things as the physiological strain in loading 120 mm ammunition within the turret workplace intended for a new tank design．The importance of this type of study was underlined by an analysis of the prototype of an advanced new armored vehicle，which the specialists in human engineering showed could only be operated by about 5 percent of the men in the Army．
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It will provide further valuable material for the scientific discipline known as ergonomics—fitting the job to the workers—to which several university and polytechnic research groups have also made important contributions．

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