REFINED ANALYSIS OF THE CORRELATION BETWEEN THE ACCEPTED MAXIMUM PERMISSIBLE LEVELS OF RADIO FREQUENCY ELECTROMAGNETIC FIELDS FOR THE POPULATION AND THE LETHALITY RATE OF COVID-19

. In this paper, the results of a refined analysis of the correlation, previously discovered by the author, between the accepted maximum permissible levels (MPL) of radio frequency electromagnetic fields (RF EMF) for population and the mortality rate of COVID-19, carried out using the data samples from the World Health Organization (WHO), taken monthly from May 2020 to July 2021, are presented. To explain the results obtained, correlation between the accepted MPL for RF EMF, the level of vaccination of population against COVID-19, and the level of gross domestic product per capita in different countries were analyzed additionally. Analysis results confirm the presence of a noticeable correlation between the RF EMF MPLs and the COVID-19 mortality rate, especially in the first months of the analyzed period. The subsequent decrease in correlation between them by the end of analyzed period is a result of significantly larger efforts in struggle against COVID-19 in those countries where high RF EMF MPLs are adopted taking into account only the danger of thermal effects in human body, in comparison with countries where more stringent standards that take into account the danger of non-thermal bioeffects, are used. The first of these countries, having on average a higher level of economic development, ensured mass COVID-19 testing of population, imposition of tougher and longer restrictions (quarantines, lockdowns, etc.), as well as significantly higher rates of vaccination of the population. correlation between these characteristics does not necessarily mean the existence of an unambiguous causal relationship between them. In countries of the first group with passive regulation of population protection from environmental factors, this principle is used not only in relation to RF EMF, but also in relation to the other factors. This determines the relevance of a deeper system analysis of the impact of the adopted legal systems for protecting the population from the entire set of anthropogenic factors on its health and collective immunity.


Introduction
Differences in maximum permissible levels (MPL) of radio frequency electromagnetic fields (RF EMF) accepted in different countries are determined by differences in approaches to ensuring the electromagnetic safety of the population in these countries [1][2][3]. The first approach is based on the principle of passive regulation, which provides for the use of recommended RF EMF maximum permissible levels (MPL), exceeding which will cause harm to health. In countries where it is adopted, MPL values of RF EMF for the population are determined taking into account the danger of thermal bioeffects only and take on values 1000-4000 μW/cm 2 , the burden of proof of possible harm from exposure to RF EMF has been transferred to the court. In a number of countries, this principle is implemented with particular socially-oriented additions aimed at limiting the RF EMF levels at socially significant objects, in places of residence, etc. An alternative second approach is based on the establishment of MPL values of RF EMF, that can guarantee the absence of harm to health, taking into account the long-term consequences of their impact on the human organism. In countries where it is adopted, the MPL values of RF EMF for the population are determined taking into account the danger of non-thermal bioeffects, and for continuous RF EMFs of the 0.3-300 GHz range they take on values 2.5-10 μW/cm 2 ; the state implements control and supervisory functions for their compliance.
Today, the main source of electromagnetic pollution of the habitat is electromagnetic radiation of base stations and a user's equipment of cellular (mobile) communication systems. At the same time, despite the very significant difference in the accepted restrictions on the RF EMF levels for the population, the differences in the degree of electromagnetic pollution of the habitat in countries with different approaches to ensuring the safety of the population were not so significant until recently [4-7, etc.] due to the prevalence of low-speed mobile telephony services, as well as the deterrent effect of the danger of massive lawsuits and huge costs of compensation for the damage caused. However, in conditions of extremely intensive development of wireless information systems and services and its penetration in all spheres of human life in the framework of the evolution 2G/3G4G5G6G of mobile communications [8,9], and in conditions of corporate pressure [10,11], restrictions on RF EMF MPL for population adopted in different countries are associated undoubtedly with the potentially permissible levels of electromagnetic pollution of the environment in these countries.
In [12], the initial results of analysis of the correlation between the potential level of electromagnetic pollution of the environment and the danger of COVID-19 are presented, which confirmed the presence of a noticeable correlation between the RF EMF MPLs adopted in different countries and the relative mortality of the population from COVID-19 in these countries. The presence of a correlation does not mean the presence of an established causal relationship between analyzed characteristics, but an extremely high cost of the item determines the relevance of its further in-depth study.
The analysis performed in [12] was preliminary in nature, since the analyzed samples of data on relative lethality from COVID-19 were taken at intervals of only 7 days over 2 weeks and, therefore, were significantly correlated (Pearson's correlation coefficient 0.996-0.999 with a sample sizes of 31, their representativeness was ensured by approximately equal representation of countries using different approaches to ensuring the electromagnetic safety of the population). The analysis of correlated samples was justified by considerations of increasing the reliability of research results in conditions of varying degrees of reliability and regularity of data updating for different countries in WHO reports 1 .
A goal of the work is to perform a more detailed analysis of correlation between the accepted RF EMF MPs for the population in different countries and the lethality of COVID-19, for a more objective assessment of the possible relation between the potential danger of electromagnetic pollution of the environment and the danger of COVID-19 for the population.

Analysis results
A deeper analysis of correlation between considered characteristics was performed using samples of COVID-19 data in various countries taken at longer intervals and over a longer period. This paper presents the results of analysis of correlation between samples of RF EMF MPL values in various countries and fifteen WHO data samples from on COVID-19 infection and mortality taken at monthly intervals from May 2020 to July 2021. This analysis is supported by correlation analysis of associated factors (the level of vaccination against COVID-19, the level of gross domestic product (GDP) per capita in various countries), which makes it possible to find an explanation of the nature of the time dependence of the analysis results.
The numbers of the data samples correspond to the following dates: No MPL values for RF EMF adopted in various countries, correspond to the published data [1-3, 12, etc.] at the beginning of the analyzed period (May 2020). Changes in the hygienic standards of separate countries (Poland, Ukraine) during the analyzed period were not taken into account, since the processes of changing the electromagnetic environment and its influence on the collective immunity of population are quite inertial and are determined by rather slow processes of corresponding changes in the infrastructure of mobile radio networks, the legal system for protecting the population, etc.
Results of a refined analysis of the correlation between the potential level of electromagnetic pollution of the environment and the lethality of COVID-19 in relation to the number of detected infected and the population size are presented below in Tables 1, 2 (in a reduced volume with data samples at two-month intervals) and in full in graphical form on parts "a", "b" in Fig. 1. These parts of Fig. 1 show both the initial dependencies in the form of broken lines, which break points correspond to the obtained estimates of the Pearson's correlation coefficient, and the curves obtained by the rootmean-square smoothing of the estimated data.
To explain the results obtained, the following was additionally performed: 1. Analysis of the correlation between the adopted EMF RF MPL for the population and the level of vaccination of population against COVID-19 in the same countries according to the official WHO data. Samples of these data were also taken strictly at monthly intervals from the beginning of mass vaccination (12/20/2020) to 07/20/2021 (8 samples). The results of this analysis are presented in Table 3 and are illustrated by graphs in the original and smoothed form on the part "c" in Fig. 1.
2. Analysis of the correlation between the adopted RF EMF MPL for the population and the level of GDP per capita, calculated according to the various methods: GDP at purchasing power parity (PPP), estimated according to the methods of the International Monetary Fund (IMF) and the World Bank (WB), and nominal GDP per capita (determining the level of the state economic development), estimated according to the methods of the IMF and the WB. Analysis results are shown in Table 4.
3. Analysis of the correlation between the relative level of vaccination against COVID-19 in various countries as of 07/20/2021 and the level of GDP per capita in these countries. Analysis results are presented in Table 5.
The presented results of the analysis indicate that countries using "thermal" hygienic standards for RF EMF MPL in combination with the principle of passive regulation in matters of population protection, on average, have a higher level of economic development compared to countries using significantly more stringent "non-thermal" EMF RF MPLs in combination with state control over their observance. This is confirmed by the presence of a noticeable correlation between the accepted value of the RF EMF MPL value and the level of GDP per capita in various countries. Depending on the methodology for GDP calculating, the coefficient of this correlation varies in the interval [0.418, 0.464]. It was the great economic opportunities of these countries that made it possible to provide: -significantly more complete coverage of the population of these countries with testing for the presence of coronavirus infection, which significantly increased the number of detected infected and by the end of 2020 practically reduced to zero the correlation between the adopted MPL RF EMF for the population and the mortality rate determined in relation to the number of detected infected, and in the latter months of the analyzed period even provided a negative correlation between the analyzed characteristics ( Table 1, part "b" in Fig. 1); -the implementation of stricter and longer administrative restrictions (quarantines, lockdowns, entry/exit bans, etc.) in these countries aimed at limiting contacts between people in order to fighting the spread of infection, as well as, on average, significantly higher rates of vaccination of population , which is generally confirmed by the data in Tables 3, 4  Part "d" in Fig. 4 contains a graphical representation 2 of the time dependence of the number of new infected according to WHO data, illustrating the nature and approximate periods of waves of the COVID-19 pandemic (first wave: October 2020 -January 2021, second wave: March -May 2021, third wave: from July 2021). For the convenience of joint analyzing dependences on parts "a", "b" and "c" in Fig. 1 and their mutual influence, part "e" in Fig. 1 shows, on a single time scale, the smoothed dependences of the Pearson's correlation coefficient on time for the lethality of COVID-19 in relation to the number of detected infected (curve 1) and in relation to the population size (curve 2), as well as the dependence of the Pearson's correlation coefficient in relation to the population vaccination rate (curve 3).
An analysis of the shape and mutual arrangement of these curves gives sufficient grounds to assume that the fact of a correlation between the degree of severity of the hygienic restrictions of the RF EMF MPL for population and the lethality rate of COVID-19 in various countries can be recognized as objectively proven based on the results of the refined analysis. At the same time, significantly larger efforts of economically developed countries to overcome the pandemic (stricter administrative restrictions, more massive testing of the population, higher rates of vaccination) contributed to a noticeable weakening of this correlation, already from the middle of the analyzed period. The lower limit of the range of normalized values. 2) The number of detected infected is given in accordance with the data of the Johns Hopkins Center for Health Security (https://covid19.who.int/). The lower limit of the range of normalized values. 2) The number of detected infected is given in accordance with the data of the Johns Hopkins Center for Health Security (https://covid19.who.int/).

3)
The population of countries is given as of 05/04/2020 in accordance with the data of the electronic resource https://www.worldometers.info/world-population/. The lower limit of the range of normalized values. 2) The percentage of vaccinated is given in accordance with the data of the electronic resource https://index.minfin.com.ua/reference/coronavirus/vaccination/.

3)
Estimated data based on total vaccine doses injected. End of Table 4 1) The lower limit of the range of normalized values.

5)
The World Bank: GDP per capita (current US$): 2018. 3) The World Bank: GDP per capita, PPP (current international $): 2020. Presented results of the analysis, despite some doubts about the reliability and comparability of the medical statistics of some countries in the information sources used, due to its integral nature with a relatively low sensitivity to such factors, in general, confirm the presence of a noticeable correlation between the RF EMF MPL for the population adopted in different countries (which determine the potential levels of electromagnetic pollution of the environment), and relative lethality of COVID-19. Before the beginning of the intensive struggle against the pandemic (at the arrival of its first wave), carried out through the implementation of strict administrative restrictions, mass testing and vaccination of the population, the Pearson correlation coefficient between these characteristics was 0.5-0.6.
2. The decrease in correlation between these characteristics by the end of the analyzed period, especially with the arrival of the second wave of the pandemic, can be explained by the larger efforts in struggle against the COVID-19 by countries where the first approach to protecting the population from RF EMF is used, compared to countries where significantly more stringent "non-thermal" hygienic standards for RF EMF MPL have been adopted. Countries that use the principle of passive regulation of the protection of the population from RF EMF and its socially oriented modifications, on average, are characterized by higher levels of economic development (the level of nominal GDP) and have more economic opportunities to struggle with the pandemic. It is reflected in significantly higher volumes of COVID-19 testing of the population, it's implementation of stricter and longer restrictions (quarantines, lockdowns, etc.), as well as in ensuring the highest rates of vaccination of the population.
3. The presence of a correlation between the adopted RF EMF MPLs for the population in different countries (which determine the boundaries of possible electromagnetic pollution of the environment during the implementation of extremely ambitious declarations and scenarios [8,9] of the development of 4G/5G/6G mobile communications), and the relative lethality of COVID-19, is not the evidence of obligatory existence of an unambiguous causal relationship between these characteristics. The fact is that in countries that use the principle of passive regulation and its socially oriented modifications, this principle is used not only in relation to RF EMF, but also in relation to other environmental factors that determine the overall level of ecology and their impact on collective immunity of the population but not taken into account in this analysis. Therefore, the detected correlation can be interpreted as a correlation between the lethality of COVID-19 and the degree of passivity (the presence of passive regulation) in protecting the population from the effects of factors that worsen the environment.
In this interpretation, the results of this analysis can serve as indirect evidence of the advantages of an alternative second approach to protecting the population from these factors (adopting MPLs that guarantee the absence of harm to health) at an intensity of their impact close to critical. Some confirmation of this assumption may be the Decision No. 20-1025 dt. Aug. 13, 2021, of the United States Court of Appeals (mandatory for the US Federal Communications Commission), on the need to abandon the "thermal" RF EMF standards, similar to [3], and develop more stringent standards that take into account the "non-thermal" effects of RF EMF exposure on public health.
4. The hypothesis [12] about the presence of a noticeable correlation between the potential levels of electromagnetic pollution of the environment and the relative mortality of COVID-19, confirmed by the results of this work, indicates the presence of a potential danger for the population of the declared development of 4G/5G/6G mobile communications. And since this development is global in nature and can both significantly enrich all areas of human existence, and significantly change the characteristics of the environment for the worse, further analysis of the possibility of actual existence of a causal relationship between these important characteristics is rather relevant.
In particular, to confirm or refute the presence of a causal relationship between the factors considered, it is of interest to analyze the actual level of electromagnetic and other pollution of the environment in the considered group of countries, as well as deep and independent studies of the influence of RF EMF created by the basic and user's radio equipment of 4G/5G/6G systems of all allocated frequency bands and modes of operation, on population health and collective immunity.
In general, the results obtained indicate the relevance of a more careful attitude to the habitat at the increasing efforts to provide information services to all aspects of human life within the framework of 4G/5G/6G evolution, using, whenever possible, alternative technologies and technical solutions where wireless data transmission is not the only possible one.