Leitgeb N, Cech R
Institut für Krankenhaustechnik mit Europaprüfstelle für Medizinprodukte, Technische Universität Graz, Osterreich.
Biomed Tech (Berl). 2005 Sep;50(9):277-81. doi: 10.1515/BMT.2005.041.
It could already be shown that electromagnetic shielding mats do not reduce but even enhance electric field exposure in daily life situations. By measurements and numerical simulations the claims of manufacturers were checked who pretend that radio frequency electromagnetic fields can be shielded to 99% and more, and transferred to earth by earth cables (if attached). It could be shown that in the radio frequency range such products do not fulfil the justified expectations of customers, but in most cases even cause the opposite. The results depend on the electric properties of the material. Good electric conductivity of shielding mats even considerably increases electromagnetic field exposure. To connect the mats with earth potential by an attached cable might increase the beliefs on a protective effect, however, this is not capable to enhance the shielding effect. The investigation demonstrates that in spite of references made to experts opinions manufacturers claims about the shielding efficiency of radio frequency fields are misleading and fool clients about the real situation. Overall, acquisition and use of electrosmog shielding mats must be discouraged. If at all, shielding can be reached by placing a shielding cover between the source and the person. However, even in this case, efficiency is much lower than promised by manufacturers and decreases even more if it is taken into account that the head naturally remains uncovered and hence unshielded.
已经可以证明，在日常生活场景中，电磁屏蔽垫不会减少反而会增强电场暴露。通过测量和数值模拟，对制造商的说法进行了检验，这些制造商声称射频电磁场可以屏蔽99%及以上，并通过接地电缆（如果连接）传导到地面。结果表明，在射频范围内，此类产品无法满足客户的合理期望，而且在大多数情况下甚至会适得其反。结果取决于材料的电学性质。屏蔽垫良好的导电性甚至会大幅增加电磁场暴露。通过连接电缆将垫子与地电位相连可能会增强人们对其保护作用的信心，然而，这并不能提高屏蔽效果。调查表明，尽管制造商提及了专家意见，但他们关于射频场屏蔽效率的说法具有误导性，会让客户对实际情况产生误解。总体而言，必须不鼓励购买和使用电子烟雾屏蔽垫。如果一定要进行屏蔽，可以在源和人之间放置一个屏蔽罩来实现。然而，即便如此，其效率也远低于制造商所承诺的，而且如果考虑到头部通常是暴露在外且未被屏蔽的，屏蔽效率会更低。
