Personal exposure from free Wi-Fi hotspots in downtown Mexico City.

In 2019, the Government of Mexico City implemented actions that allowed citizens to approach a free Wi-Fi hotspot, where more than 13000 points have been installed throughout the city. In this work, we present the results of the measurements of personal exposure to Radiofrequency Electromagnetic Fields carried out in Plaza de la Constitución, better known as Zócalo located in the center of Mexico City. The measurements were taken by one of the researchers while walking on a weekday morning and afternoon, in different microenvironments (on the street, on public transport: subway, at the Zócalo, and finally, at home). We also carry out spot measurements in the center of the Zócalo. Subsequently, we carried out a comparative analysis of the different microenvironments, through box plot and violin plot, and we elaborate georeferenced and interpolated maps with intensity levels through the Kriging method, using the Geographic Information System. The Kriging interpolation gives us a good visualization of the spatial distribution of RF-EMF exposure in the study area, showing the highest and lowest intensity levels. The mean values recorded at the measured points in the Zócalo were 326 µW/m2 in the 2.4- to 2.5-GHz Wi-Fi band and 2370 µW/m2 in the 5.15- to 5.85-GHz Wi-Fi band. In the case of the mean values recorded on the street, they were 119 µW/m2 in the 2.4- to 2.5-GHz frequency band and 31.8 µW/m2 in the 5.15- to 5.85-GHz frequency band, like the values recorded at home, 122 µW/m2 and 33.9 µW/m2, respectively. All values are well below the reference levels established by the International Commission on Non-Ionizing Radiation Protection.

Comparison of personal exposure to Radiofrequency Electromagnetic Fields from Wi-Fi in a Spanish university over three years.

In this work we present the personal exposure levels to Radiofrequency Electromagnetic Fields (RF-EMF) from Wireless Fidelity (Wi-Fi) 2.4 GHz and 5.85 GHz bands in a Spanish university, specifically, at the Faculty of Computer Science Engineering at the University of Castilla-La Mancha (Albacete, Spain). We present results from three years, 2017, 2018 and 2019 in the same study place and points; and measurements carried out in 2022 inside a classroom and inside a professor's office, with the aim to compare the measurements and verify compliance with reference levels established by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The minimum average was 0.0900 µW/m2 in the 2.4 GHz Wi-Fi, in 2019, and the maximum average was 211 µW/m2 in the 5.85 GHz Wi-Fi in 2017, around the building. Comparing the measurements carried out inside the classroom with students and without students, we identified that the maximum value was 278 µW/m2 (classroom with students, in the 5.85 GHz Wi-Fi band) and the minimum value was 37.9 µW/m2 (classroom without students, in the 5.85 GHz Wi-Fi band). Finally, comparing the results of all the measurements (average values) inside the classroom and inside a professor's office, the maximum value was 205 µW/m2 (in the 5.85 GHz Wi-Fi band) inside the classroom with students, and the minimum value was 0.217 µW/m2 inside a professor's office (in the 2.4 GHz Wi-Fi band). These values in no case exceed the limits established by the International Commission on Non-Ionizing Radiation Protection, 10 W/m2 for general public exposure.

Comment on Martin L. Pall "Millimeter (MM) wave and microwave frequency radiation produce deeply penetrating effects: the biology and the physics", Rev Environ Health, 2021.

In this letter, we present some comments related to Pall's publication, in which Pall states that the electric field disappears after a few centimeters and that the magnetic field continues progressing within the studied material.