Workwear laid bare
February 1st 2008

The relationship between clothing and the human organism is often veiled in ignorance: questions like – what happens to the body when subjected to different workloads – and – how does the wearer benefit from physiologically designed protective clothing – are fundamental to the effective health care of outdoor workers, explains Gore

The human body relies on a stable thermal balance in order to function properly. Of key importance here is body core temperature, which should be maintained at a fairly constant 37 degrees centigrade. If an upward or downward deviation is triggered by physical exercise or a change in ambient temperature, the body’s regulatory processes kick in to restore this balance.

Response to changes in temperature

Mild physical exercise or a minor change in ambient temperature produces only a slight rise in body core temperature. The resultant heat is then transferred to the outside by radiation, respiration and/or convection. However, during sustained strenuous physical exertion or high ambient temperatures surplus heat builds up which the body tries to get rid of through an additional cooling system, the formation of perspiration on the skin. The purpose of perspiration is to cool the skin down by the evaporation of sweat. If over a prolonged period more heat is produced than can be transferred, this can lead to an unhealthy rise in body core temperature, signalled by an incipient feeling of discomfort. Further overheating results in the wearer experiencing nausea, blurred perception and reduced efficiency. Long recovery phases are required.

Conversely, at low temperatures the body tries to protect the internal organs and maintain a constant core body temperature by reducing the blood supply to the cold zones such as feet, hands and face. But this only works in the short term. After that the body core temperature drops, which increases the feeling of discomfort. Severe hypothermia over a prolonged period, triggered by low ambient temperatures, wind or perspiration-soaked clothing, leads to impairment of various subsystems in the body. This often results in increased susceptibility to infection, deterioration of fine motor activity, increased risk of cramp and rheumatic complaints, and above all reduced efficiency.

Physiological properties of modern protective clothing

The main purpose of protective clothing is to protect the wearer from risks posed by external influences. This means that clothing must protect against wet, wind, heat, chemicals, mechanical action and other hazardous influences. It also acquires a “quasi-physiological“ importance as the second skin separating man from the environment.

In addition to providing protection against external influences it has to ensure the thermophysiological equilibrium of the human body if it is to contribute effectively to health protection. This means it must assist the body in transferring to the environment the excess heat and moisture produced under high workload or ambient climatic conditions, or to a large extent take over this transfer. Health-protection garments should therefore be made from materials of adequate water vapour permeability. Such breathable clothing should also insulate against wind and cold (heat insulation) and protect the body from wet (waterproofness). This also ensures that perspiring skin does not cool down more than predicated by the amount of perspiration given off.

EN 343, the pan-European Standard for weather-protective clothing, takes account of protection from wet and moisture as well as the level of water vapour permeability. Taking a minimum standard as its starting point, the Standard differentiates between each of 3 performance ratings for weatherproof clothing, dependent firstly on its degree of resistance to the water penetration (measure of water-proofness), and secondly on its degree of water vapour resistance (measure of breathability). Just recently, for example, the Municipal Street Cleaning Division in Vienna bought high-visibility and weather-protective clothing with the waterproof, windproof and breathable GORE-TEX membrane which achieves the best figures for breathability and waterproofness in each of the highest EN 343 requirement categories.

Protective clothing which can cope with multiple physiological requirements should be considered as an integrated system. Like the skins of an onion, all the individual layers of clothing must function in a coordinated way:

• The base layer, functional underwear as a rule, creates a pleasant microclimate next to the skin. It wicks moisture away from the skin surface and transfers it to the next layer, so perspiration cools the body without soaking underwear and making it clammy
• The second layer usually provides heat insulation, thus acting as cold protection. It generally comprises a fleece component which absorbs moisture from the bottom layer and transfers it to the next layer
• The third and outer layer, also called the shell, is used as weather-proofing. This is mostly clothing incorporating functional material, e.g. the windproof, waterproof and breathable GORE-TEX membrane. Nowadays weatherproof jackets are often combined with a detachable, zipped heat-insulating fleece component for cold protection

This type of integrated clothing system is also becoming increasingly popular in the world of work. One particularly good example is the new workwear concept of the Austrian Police, in which some 20 of the system’s garments were rigorously developed and coordinated to meet physiological criteria – from head to toe. Effective protection with no gaps: from inside to outside and head to foot.

Functional workwear

However the wearability of modern protective clothing is not just determined by its physiological properties. At least equally important is the functional construction of the garment, a cut adapted to the movements typical of a specific occupation, and attractive design. Another key factor in making protective clothing acceptable to the wearer is that development work should incorporate accurate findings on the requirements imposed by workplace and ambient conditions.

The trend here is very much towards the use of ever more specific functional materials and garment designs tailored to a particular use. Moreover everyone concerned, wearers as well as garment manufacturers and buyers, should be involved in developing new types of clothing.

Economic benefits of physiologically coordinated protective clothing

In a difficult economic climate employee health also becomes an increasingly important production factor.

Today more than ever companies rely on an efficient workforce to maintain their long-term competitiveness. Physiologically coordinated protective clothing can reduce the illness risk of employees working outdoors and prevent associated illness-related absences and supplementary costs.

Under these circumstances companies are noticeably accepting responsibility for the health care of their employees and as a precaution kitting them out with physiological, high quality protective clothing. For instance, a medium-sized car wash operator in Remscheid/ Germany bought waterproof, breathable GORE-TEX protective clothing for his workers and cut sickness by 30% in one year. Other positive effects were that staff felt high quality clothing to be a token of appreciation and demonstrated more motivation, commitment and keenness. And even customers were impressed by the company’s new professional image.

More articles from WL Gore & Associates Limited: