## 1 Introduction  
Recently, a growing interest in the issues related to the influence of electromagnetic (EM) waves on the human body has been observed. This subject is especially important for people who feel fear of the effects of EM radiation emitted by wireless communication systems, which applies in particular to fifth generation (5G) systems [1]. This is caused mainly by a visible change in the telecommunication infrastructure that requires placing new base station equipment for this new generation of wireless system. These situations may cause the development of irrational behavior in a certain group of people, which are the subject of research by psychologists [2]. Many of these people consider themselves to be particularly sensitive to radiation and seek a way to minimize their exposure to EM fields. As a result of these fears, they fabricate by themselves and use improvised head covers made of conductive materials such as thin aluminum foil [3]. The purpose of this so-called \"infoil hat\" is to protect the user against electromagnetic fields; however, covers of this type are created spontaneously without taking into account the physical phenomena of electromagnetic wave propagation. Often, they are merely the result of a creative reworking of certain observations linking conductive materials to electromagnetic shielding structures. The research on electromagnetic shields of human body is very challenging because of the problem intricacy. This is due to the complex mechanism of interaction of the electromagnetic wave with the tissues of the human body, which depends on wave parameterssuch as frequency and polarization. Moreover, the structures used to be placed close to the body have a complex shape resulting from the use of flexible materials that conform to the shape of the body. In this case, computer simulations can be used. However, they must enable the modeling of both the complex internal structure of the body as well as the thin layers of the conductor placed nearby. This is a task that requires considerable computational effort because thin layers of shielding materials should be mapped using high-resolution discrete models, whose unit cells are not larger than 1 mm. Such models, taking into account even a small area of the body such as the head, require large computing resources, especially in the field of computer memory, in which more than 41 million unit cells should be modeled. Regardless of these difficulties, the problem is so significant that it motivated me to conduct the research described in this article. The motivation for conducting the research described in this article came from numerous conversations the author had with people who were particularly concerned about 5G base station radiation and wanted to use infoil hats. In the literature, there are no data on improvised head shields effectiveness at the frequencies of 5G systems. With this novel research I wanted to bring the science-based evidence that could be used during such discussions. It shows the effectiveness of metal shields and provides numeric data that illustrate this effect. For this purpose, I used well-established methodology--computer simulation with the FDTD method and a numerical model of the human body. In the literature, the shielding structures applied for the human body are studied for the case when the cell phone is the source of electromagnetic radiation [4; 5; 6], while the development of multipurpose shielding materials assumes a plane wave [7; 8]. The research carried out with respect to interactions of electromagnetic waves with the human body shows that both construction and the materials used for the human body shield design influence its performance. In [4], the effects of an electromagnetic field over a virtual model of a human head have been simulated in the frequency range from 900 to 1800 MHz.