## 1 Introduction  
The operation of radio-frequency (RF) electromagnetic field (EMF) sources, especially in residential areas, has been a matter of concern over recent years. The growing demand for wireless communications in recent decades has resulted in the installation of a rapidly increasing number of RF emitters. Thus, there is a strong interest in assessing the potential health hazards associated with RF radiation, especially in environments where sensitive population groups are present such as schools, hospitals, and eldercare facilities. A great number of experimental studies have been performed in an attempt to evaluate the exposure of the public to nonionizing radiation emitted by RF sources. A systematic review of the studies conducted in Europe between 2000 and 2015, on the public RF exposure in everyday environments, has been presented by [PERSON] et al. [1]; an update for the period between 2015 and 2018 has also been reported [2].  
Information about RF exposure levels in environments relevant to children, such as schools, kindergartens, and playgrounds, may be found in the literature [3, 4, 5, 6, 7, 8, 9, 10, 11], but,generally, the investigation of children's EMF exposure is somewhat limited. Outdoor and indoor environmental, as well as personal, RF exposure has been examined in places where children are mostly present. [PERSON] et al. [3] conducted EMF measurements in kindergartens in Melbourne, Australia; [PERSON] et al. [4] carried out spot and personal measurements in homes, schools, and parks in Spain; [PERSON] et al. [5] performed spot measurements at RF and extremely low-frequency (ELF) bands inside and outside school buildings in Turkey; while the personal exposure of children to RF-EMF radiation in Europe has been extensively studied by [PERSON] et al. [6]. Moreover, several researchers have examined the RF exposure of children in microenvironments, by conducting indoor measurements in homes, schools, and creches in Belgium and Greece [7] and in Amsterdam schools [8]. In addition, a study of the temporal variation in children's RF exposure in homes and schools has been presented [9].  
Recently, [PERSON] and [PERSON] [10] reported the results of an experimental campaign carried out by the Greek Atomic Energy Commission (EEAE); in situ measurements of RF-EMFs and ELF electric and magnetic fields were carried out in children's playgrounds all over Greece, in urban and suburban areas. Furthermore, a statistical analysis for the RF exposure levels in Greek schools, based on pilot measurements conducted in 65 schools, was presented by [PERSON] et al. [11]. Other studies, regarding the general public RF exposure in Greece, include the continuous monitoring of the EM radiation in the environment [12; 13], the performance of measurements in the vicinity of base stations all over Greece [14], and the development of a national telemetric network to monitor the EMF levels from all kinds of antenna stations in the range of 100 kHz-7 GHz [15]. In addition, the occupational exposure to EMFs has been investigated in specific workplaces in Greece [16].  
In this study, we present the results of frequency-selective and broadband EMF measurements conducted around schools in Crete island, Greece, in the frequency range of 27 MHz-3 GHz. The electric (E-) field strength was recorded in seven specific bands, as well as in the whole aforementioned range. The exposure ratio was calculated and the results were statistically analyzed and evaluated by examining the compliance with the established exposure reference levels for RF exposure in Greece.