Fernanda E. S. Galdino

Non-ionizing radiation is the subject of several applications, such as the microwave oven, which is very popular. Its use is characterized by direct user operation and reduced distances between users and the NIR source. Therefore, the level of human exposure in this scenario deserves attention as it is a potential cause of biological effects. In this sense, this paper presents the measurement of a microwave oven with a high level of NIR (above the limit defined by the standard) before and after two types of suggested repairs: the use of epoxy putty (Repair 1) and the replacement of the external surface of the oven (Repair 2). The definitions of measurement methodology, based on FDA and INMETRO standards, are presented and discussed. Finally, we describe an analysis of the efficiency of these repair methods aiming at the safety operation.

Due to the low cost of broadband systems, there is a substantial growth in the indoor deployment of networks based on IEEE 802.11 standards, and their expressive insertion in domestic and labor environments. The proximity of those systems to the general population has been raising questions about the risks of exposure to the so-called non-ionizing radiation (NIR), since network equipment is radiofrequency electromagnetic field emitter. This work aims to measure and evaluate the levels of Non-Ionizing Radiation (NIR) by verifying the intensity of the NIR generated by the wireless network devices in residential environments. The ISM 2.4 GHz and 5 GHz frequencies used in Wi-Fi systems are the focus of this investigation. The measurements were conducted and analyzed according to Act No. 458 (January 2019) of the National Telecommunications Agency (ANATEL) and Law no 11. 934 (May 2009). Measurements of electric field (EF, in V/m) are compared to the exposure limits for the general public, as established by Brazilian legislation. Thus, the highest measurement for EF peak value was 7.16 V/m, corresponding to a percentage of 11.74 % of ANATEL limit.

It is crucial to monitor the levels of Non-Ionizing Radiation (NIR) to which the general population may be exposed and compare them to the limits defined in the current standards, in view of the rapid rise of communication services and the prospects of a connected society. A high number of people visits shopping malls and since these locations usually have several indoor antennas close to the public, it is therefore a kind of place that must be evaluated. Thus, this work presents measurements of the electric field in a shopping mall located in Natal, Brazil. We proposed a set of six measurement points, following two criteria: places with great the flow of people and the presence of one or more Distributed Antenna System (DAS), co-sited or not with WiFi access points. Results are presented and discussed in terms of the distance to DAS (conditions: near and far) and flow density of people in the mall (scenarios: low and high number of people). The highest peaks of electric field measured were 1.96 and 3.26 V/m, respectively corresponding to 5% and 8% of the limits defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Brazilian National Telecommunication Agency (ANATEL).