Protective polymers

Restrictions have been imposed to prevent the spread of the SARS-CoV-2 virus. Wearing a mouth and nose mask is part of this, as is avoiding and reducing social contact and maintaining safe distances up to more far-reaching quarantine measures. Where it is difficult to keep a distance, plastics fulfil a key barrier and protective function.

The daily news in the media is worrying: the number of people who have tested positive for the coronavirus SARS-CoV-2 is high despite the "lockdown". Hundreds are said to die every day with or as a result of infection with this coronavirus variant in Germany and elsewhere. Science is making progress in understanding the invisible enemy, deciphering more and more its influence on our immune system and the various organs and processes in the human organism. Nevertheless, medicine has so far had few therapeutic options to counter it. Political leaders  are propagating what they see as the only solution: a vaccination to deprive the virus of its proverbial sting. Although the question remains unanswered, as politicians say, whether this will avert the danger and allow humanity to return to a normal everyday life.

Prophylaxis is the key to success. This refers to those measures that prevent or avoid an infection and nip it in the bud. Whether it is possible to completely prevent the chain of spread of a virus transmitted via the respiratory tract is, however, questionable in view of the spreading illness. Nonetheless, the speed and scope of the observed infection process can be slowed down by following the measures described above.

Many processes that make modern life possible and that map our everyday life may be brought to a temporary standstill. Nevertheless, an industrial society cannot simply be put into a fairytale-like hibernation. That would be its ruin. It needs vehicles that help keep the life engine of society running and enable functioning togetherness at all levels, while at the same time adhering to necessary safety measures. Distance, for example. But not everything can be regulated via telephone or internet. In many cases, direct visual contact is needed - that's how people are, that's how many processes are. A conversation between doctor and patient, for example, may be possible by telephone or video link. But it remains questionable whether a medical anamnesis really works just as effectively without the doctor seeing the patient directly. Other things, however, as the view through a window pane makes clear, can be regulated if one is separated from the other by a transparent screen, insofar as a conversation is possible.

Some politicians associate pandemic with the term war. However, viruses are not enemy soldiers or terrorists. Thus, unlike a bank or other security-relevant areas, a spit shield does not need impact-, bullet- or explosion-resistant laminated safety glass to prevent infection with pathogens. This is, incidentally, sandwich-like in structure and contains the plastic polyvinyl butyral (PVB). This polymer prevents the typical shattering effect of glass and is characterised by high tear resistance. Car windscreens are made of safety glass and contain PVB.

Whether at the bread, sausage or cheese counter, at the ticket counter in the ice rink or concert hall, at the supermarket checkout or now also in restaurants or state parliaments – wherever people come face to face, there is always the risk of transmitting respiratory germs. These include the viruses that classically trigger colds and respiratory diseases. They are transmitted with the air we breathe. According to the current state of science, the novel coronavirus is mainly transmitted via droplet infection and less via smear infection. Salivary and nasal discharge are therefore considered to be of particular concern. Accelerated to high velocities by sneezing and coughing, these bodily secretions, which may be highly contaminated with germs in the event of illness, spread spatially. The task of plastic walls made of Plexi or acrylic glass (polymethyl methacrylate, PMMA), which are now installed in shops, restaurants, bakery counters, confectioneries, doctors' registration desks or hotels, is to contain their spread and protect the other person from infection. Being able to see and talk to each other and being protected at the same time is no problem with the right plastics.

The news reports about dramatic situations in intensive care units in hospitals everywhere. It is not so much that beds and technical equipment are lacking. Rather, there is a lack of well-trained nursing staff who are trained in dealing with patients who require intensive medical treatment and are also highly infectious. The risk of infecting oneself at work seems high because of the environment, but with the appropriate protective equipment combined with its correct handling, the risk can be reduced to a minimum. However, if nursing staff are absent due to illness, this has a lasting effect on the processes on the ward, as has been shown. The remaining staff must fill the gaps and perform more. The workload under which nurses are currently performing their duties, especially in affected intensive care units and also in geriatric care facilities and in corona hotspot hospitals, is immense. In order to protect themselves from infection with pathogens, medical staff put on personal protective equipment (PPE). This includes an adequate mask that covers the mouth and nose and is adapted to the environment. Classic hygiene masks consist of a multi-layer fleece and are placed on the face with latex-free rubber straps that are placed behind the ears and by means of a flexibly adjustable nose clip. Higher demands in terms of filtering performance are met by masks equipped with polymer-based particle filters and, if necessary, ventilation valves. Eyes can be protected from flying viruses with shatterproof goggles with lenses also made of polycarbonate.

To prevent widespread contamination of clothing and the spread of germs, PPE includes gloves, which can generally serve to protect against soiling, injury, aggressive substances and also the spread of pathogens. What a glove is able to do depends not least on the material it is made of. Sterile medical protective gloves, for example, are made of various plastics such as nitrile rubber (acrylonitrile butadiene rubber, AB/ABR), polyethylene (PE), latex (colloquially known as rubber) or vinyl (made on the basis of polyvinyl chloride, PVC). In the medical environment, these gloves fulfil the function of protecting doctors and nursing staff from infection with pathogens, for example in contact with blood, secretions or bodily excretions. Finally, the protective shield is completed by protective gowns and suits made of a polypropylene-polyethylene mixture (PP/PE), as well as disposable overshoes made of PP.

In some chemical and biological or medical hazardous situations, the protective equipment described above does not meet the requirements. The manufacture and classification of PPE is based on a directive (89/686/EEC). According to the Robert Koch Institute (RKI), PPE is divided into three categories in this country: Category I comprises simple protective equipment for low risk of health hazards. Category II is protective suits to ward off hazards not covered by categories I and III. Category III applies to protective equipment for use against lethal hazards or in the event of serious consequential health damage such as the case of Ebola.

Ebola is an infection that is often very severe, accompanied by fever and bleeding (haemorrhagic fever). The disease is triggered by the Ebola virus of the same name, which is one of the most dangerous pathogens in the world; so far, there are no effective drugs or vaccinations against the infection, which is fatal in very many cases. Because person-to-person transmission occurs through direct physical contact as well as contact with the blood or other excretions of infected persons, and given the severity of the infection, somewhat different protective gear is required. Liquid-tight protective clothing is needed, which can also be cleaned and reused after use, if necessary, by appropriate means and procedures. If there is also a health risk from inhaling dangerous pathogens or substances, a protective suit is needed that has a filter fan or its own compressed air supply. In extreme cases, firefighters and rescue workers use a protective suit that has a maximum barrier effect against a wide range of different, highly concentrated organic and inorganic chemicals as well as against the most dangerous biological pathogens. Polymer materials stand for safety and comfort here.