Gum On Skin
Large fires, terror alerts, outbreaks of epidemics: where such catastrophes happen, emergency services often appear in protective clothing. Hardly anyone asks them if they feel comfortable in their gear.
People in protective suits are part of the image of modern society. You can usually see him from afar, behind red and white barriers. Bright white, bright orange or bright yellow, he flickers on TV screens, picks rotten birds from the beach, searches offices for terrorist poisons or puts chickens in plastic bags.
People in protective suits radiate fascination. That was the case ten years ago when the movie "Outbreak" hit the cinemas. The actors Dustin Hoffman and Rene Russo, dressed in a colorful body shell, tackle a killer virus. The film posters showed this motif in particular: the faces of the actors behind the glass of the protective helmet. A strong image, the strip did fantastic.
But how does a person in a protective suit feel? Not always good. "Perspiration is a big problem," says Volkmar Bartels from the Hohenstein Clothing Physiology Institute in Bönnigheim. "A big problem is sweat"
(Volkmar Bartels) Many protective combinations have water-repellent properties, they don't let the wet element in - but they don't let it out either. The result: Body moisture collects and the suit gets soaked from the inside. "This," says Bartels, "is perceived as very uncomfortable by the wearer."
Only as much security as necessary
Bartels has carried out a large research study together with his institute colleagues. They investigated how the wearing comfort of chemical protective suits can be improved. They scrutinized NBC protective clothing, chemical worker suits, disposable protective suits and items of clothing made from high-strength chemical fibers that are used, for example, for bulletproof vests.
The most important finding of the researchers: the better the protective effect, the less comfortable the wearer feels. "Anyone who buys a protective suit should think very carefully about what they need it for," says Bartels. Only as much protection should be available as is really needed.
The example of the US fire department shows this particularly drastically. "Of the American firefighters who die in action, half die from overexertion-heatstroke, circulatory collapse, and heart failure," Bartels said. "If you buy a protective suit, you should think very carefully about what you need it for"
(Volkmar Bartels) The protective suits are often to blame because they do not adequately dissipate sweat and body heat. Increasing the level of protection in the suits wouldn't make sense for firefighters: Over-exertion is their number one cause of death, far ahead of any other risk.
The problem of water and heat build-up is present in almost all protective clothing, even in everyday chemical worker suits – a kind of overalls to keep out chemical splashes, like those worn by industrial workers. So-called laminates, which are composite materials made of different substances, can help here. "A laminate typically consists of three layers: a skin-friendly base material made of natural material, a Teflon film and an outer material made of chemical fibers," says Jan Beringer, textile chemist at the Bönnigheim Institute. The same principle would be found in Gore-Tex clothing. The tests had shown that laminates are able to dissipate body heat and sweat better than conventional materials.
Annoying side effects
Another problem is that protective clothing is often very slippery on the inside where it lies against the skin – especially with synthetic fibers. It can stick to sweaty skin, which causes great discomfort. "This can be avoided by roughening the inside of the clothing so that there is a gap to the skin's surface," says Bartels. One way to do this is to use a layer of fabric made from staple fibers for the inside of the set.
Because of the synthetic fibers, some protective suits also become electrostatically charged. If the wearer then touches a doorknob or a water tap, a spark can fly. "This is not only uncomfortable for people, but can also be really dangerous - if the suit wearer is in potentially explosive rooms, for example," explains Bartels. It is therefore stipulated that many protective suits do not become appreciably charged when they are worn.
ABC protective clothing provides the most effective protection. It contains layers of activated carbon – extremely finely atomized carbon that, among other things, binds penetrating war gases. The tests carried out by the Bönnigheim researchers have shown that the activated carbon absorbs the wearer's sweat. On the one hand, according to Bartels, this is not bad because body moisture does not collect on the skin. On the other hand, this would make the suit thicker, heavier and stiffer. This can cause skin irritation and cause the body's vapors to be dissipated more and more poorly. The scientists' recommendation: ABC clothing should only contain as much activated carbon as is absolutely necessary.
With artificial skin and copper dolls
The researchers from Bönnigheim have been investigating protective clothing for many years. They have developed sophisticated methods for their experiments. For example, they have an apparatus for mimicking human skin: a special stainless steel plate with many small openings. The researchers bring this plate to 35 degrees Celsius – the typical surface temperature of a human being – and add water from below. About as much water vapor escapes from the openings as from the skin pores of a human being.
"Over the course of a night," explains Bartels, "each of us secretes about a quarter of a liter of water over the surface of our bodies – it all ends up in the bed linen." If the scientists place a piece of protective clothing on the steel plate, they can find out how well the textile lets water vapor through. In addition, the researchers still have "Charlie". This is a life-size copper dummy that can be used to adjust the temperature of individual parts of the body. If you dress Charlie in a protective suit, you can see whether the clothing causes heat to build up or not. This also allows conclusions to be drawn as to where the sweat will collect.
"Of course, we also let real people assess the comfort of protective clothing," says Bartels. However, such attempts are very time-consuming. Because people differ greatly in their feelings, both among themselves and from day to day. "Until we get reasonably meaningful measurement results," says Bartels, "we have to carry out many fittings with many participants - that takes time and costs."
Bönnigheim researchers keep hearing complaints about uncomfortable protective suits - especially from industry and in summer. Many of these problems, says Bartels, are avoidable. "Over the course of a night, each of us excretes about a quarter of a liter of water over the surface of our bodies"
(Volkmar Bartels) They stemmed from employers buying cheap, low-quality protective suits - often imported - to keep their operating expenses down. The workers who have to use the suits bear the brunt of the damage."Unfortunately," summarizes Bartels, "many buyers are of the opinion: the cheaper, the better. That's bad."