###### Abstract  
The recent development of millimeter-wave (mmW) technologies, such as the fifth-generation (5G) network, comes with concerns related to user exposure. A quite large number of dosimetry studies above 6 GHz have been conducted, with the main purpose being to establish the correlation between different dosimetric parameters and the skin surface temperature elevation. However, the dosimetric studies from 28 GHz user equipment using different voxel models have not been comprehensively discussed yet. In this study, we used the finite-difference time-domain (FDTD) method for the estimation of the absorption of radiofrequency (RF) energy from a microstrip patch antenna array (28 GHz) in different human models. Specifically, we analyzed different exposure conditions simulating three real common scenarios (a phone call scenario, message writing scenario, and browsing scenario) regarding the use of smartphones/tablets by four different individuals (adult male and female, child male and female). From the results of Absorbed Power Density (Sab), it is possible to conclude that all the considered exposure scenarios comply with the safety limits, both for adult and children models. However, the high values of the local Specific Absorption Rate (SAR) in the superficial tissues and the slight differences in its distribution between adults and children suggest the need for further and more detailed analysis. 5G; mmW; numerical dosimetry; smartphone exposure +
Footnote †: journal: International Journal of and Public Health  
_Article_  
Numerical Analysis of Electromagnetic Field Exposure from 5G Mobile Communications at 28 GHZ in Adults and Children Users for Real-World Exposure Scenarios  
[PERSON], [PERSON], S. S.  
has become important to evaluate any harmful effects on health caused by electromagnetic fields [6]. There is a dire need to study the absorption of electromagnetic energy in human tissues due to exposure to mmW radiation. To protect human bodies from exposure to mmW radiation, many countries set safety guidelines standards, such as those set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [7] and the Institute of Electrical and Electronics Engineers (IEEE) [8], as well as the Federal Communications Commission (FCC) [4]. Most of the studies about the exposure assessment of the human body to RF radiation in complicated exposure conditions used numerical approaches such as numerical analysis based on the finite-difference time-domain (FDTD) method [9; 10; 11; 12; 13]. A quite large number of dosimetry studies above 6 GHz have been conducted [14; 15; 16; 17; 18; 19; 20; 21; 22], with the main purpose to establish the correlation between different dosimetric parameters such as the specific absorption rate (SAR), absorbed power density, and the skin surface temperature elevation. In 2017 [PERSON] et al. [18] presented a detailed numerical dosimetry study with a 60 GHz antenna module for two representative human body exposure scenarios within 5G small cells. They used the numerical model of an adult human head together with a human hand that held a smart-phone. For the numerical analysis, the finite integration technique was implemented together with a finite element method used to better characterize the antenna. As dosimetric parameters, SAR absorbed power and equivalent incident power density was used. The finding of this study was that the maximum absorption occurs on the surface of the user's ear (for the phone call scenario) and fingertips (for the browsing scenario). In 2018, [PERSON] and colleagues [19] investigated the SAR distributions due to a radiating source antenna using the FDTD method in single and layered human tissues by evaluating the SAR 1g and point SAR (without mass averaging) at frequencies of 28, 40, and 60 GHz. The results concluded that at the radiated power of 20 and 24 dBm, SAR levels (without mass averaging) in the tissues at 28 GHz were less than 40 and 60 GHz.