Information Dynamics of Electric Field Intensity before and during the COVID-19 Pandemic.

This work investigates the temporal statistical structure of time series of electric field (EF) intensity recorded with the aim of exploring the dynamical patterns associated with periods with different human activity in urban areas. The analyzed time series were obtained from a sensor of the EMF RATEL monitoring system installed in the campus area of the University of Novi Sad, Serbia. The sensor performs wideband cumulative EF intensity monitoring of all active commercial EF sources, thus including those linked to human utilization of wireless communication systems. Monitoring was performed continuously during the years 2019 and 2020, allowing us to investigate the effects on the patterns of EF intensity of varying conditions of human mobility, including regular teaching and exam activity within the campus, as well as limitations to mobility related to the COVID-19 pandemic. Time series analysis was performed using both simple statistics (mean and variance) and combining the information-theoretic measure of information storage (IS) with the method of surrogate data to quantify the regularity of EF dynamic patterns and detect the presence of nonlinear dynamics. Moreover, to assess the possible coexistence of dynamic behaviors across multiple temporal scales, IS analysis was performed over consecutive observation windows lasting one day, week, month, and year, respectively coarse grained at time scales of 6 min, 30 min, 2 h, and 1 day. Our results document that the EF intensity patterns of variability are modulated by the movement of people at daily, weekly, and monthly scales, and are blunted during periods of restricted mobility related to the COVID-19 pandemic. Mobility restrictions also affected significantly the regularity of the EF intensity time series, resulting in lower values of IS observed simultaneously with a loss of nonlinear dynamics. Thus, our analysis can be useful to investigate changes in the global patterns of human mobility both during pandemics or other types of events, and from this perspective may serve to implement strategies for safety assessment and for optimizing the design of networks of EF sensors.

The SEMONT continuous monitoring of daily EMF exposure in an open area environment.

Wireless networks traffic has experienced a considerable growth in recent years. Likewise, it is to be expected that billions of objects will be connected to the Internet in years to come, many of them wirelessly. Such increase in a number of wireless connections and the inevitability of wireless communications in proximity of users highlight the healthcare concern on electromagnetic field (EMF) exposure. Thus, the intelligent monitoring systems, such as the Serbian Electromagnetic Field Monitoring Network-SEMONT-have been required to be developed and utilized for continuous and real-time EMF monitoring, as well as for the assessment of the potential in situ daily exposure of population. This paper presents the results of the SEMONT initial campaign of continuous monitoring of the high-frequency electric field strength over the campus of the University of Novi Sad, as an open area environment. Several locations, most frequently visited by the student population in their everyday activities, have been monitored during the rush hour in order to determine the fluctuation of daily exposure on this, usually considered, highly sensitive area. The results of monitoring suggest that potential exposure is far below the allowable limit, regarding reference levels prescribed by the Serbian legislation for the general population.

The measurement procedure in the SEMONT monitoring system.

The measurement procedure of the open area in situ electric field strength is presented, acquiring the real field data for testing of the Serbian electromagnetic field monitoring network (SEMONT) and its Internet portal. The SEMONT monitoring system introduces an advanced approach of wireless sensor network utilization for the continuous supervision of overall and cumulative level of electromagnetic field over the observed area. The aim of the SEMONT system is to become a useful tool for the national and municipal agencies for the environmental protection, regarding the electromagnetic pollution monitoring and the exposure assessment of the general population. Considering the public concern on the potentially harmful effects of the long-term exposure to electromagnetic radiation, as well as the public transparency principle that is incorporated into the Serbian law on non-ionizing radiation protection, the SEMONT monitoring system is designed for the long-term continuous monitoring, presenting real-time measurement results, and corresponding exposure assessment over the public Internet network.