Possible adverse effects on human health due to exposure to non ionizing electromagnetic fields has led International Organizations and several countries to adopt exposure limits regarding public or occupational safety. To ensure compliance with these limits, specifically designed measurements with suitable instruments have to be performed. Since uncertainty is always present even when expensive and well calibrated and accredited instrumentation is employed, the final results from computations on the measured data deviate from the respective true values. The divergence depends either on the instrumentation employed or on the used methodology, or even on other random effects e.g. human factors or environmental conditions.
The non Ionizing Radiation Laboratory (NIRL) of Applied Informatics and Multimedia Department of the Technological Educational Institute of Crete, is carrying out measurements in the vicinity of equipment transmitting electromagnetic fields in the RF and ELF regions of the electromagnetic spectrum, according to the Greek Legislation and other National and International recommendations and standards.
In this tutorial measurement procedures and post processing of measurement data that NIRL applies to evaluate the compliance to the Legislated Reference Levels of human exposure to Non Ionizing Electromagnetic fields in the RF Region are presented. Therefore, NIRL has developed a special purpose software to process the measurement data and produce a large part of the measurement report, which incorporates all necessary information (measurement data, uncertainty estimation etc). The operation of this software and its results are also presented.

Transmission, distribution and use of electric power leads to the generation of electric and magnetic fields at low frequencies usually referred as Extremely Low Frequency (ELF) fields. This is a potential hazard to human health and research is being carried out to investigate the possible adverse effect of the ELF field exposure to humans. Until now there is no satisfactory answer to the question whether common exposure to ELF fields should be considered as a health hazard. Meanwhile international organizations and national legislation have adopted Reference Levels (RLs) for the maximum permissible human exposure to ELF. To assess ELF exposure compliance, on site measurements have to be performed for magnetic end electric field strength by authorized personnel and results from data processing have to be compared to RLs. One issue when performing such measurements is the estimation of the exposure level especially in cases where measured values are close to the established RLs. In such cases measurement uncertainty must be estimated which usually depends on the used instrumentation and environmental parameters.
This tutorial presents the instrumentation and the procedures that the Non-Ionizing Radiation Laboratory (NIRL) of Applied Informatics and Multimedia Department of Technological Educational Institute (TEI) of Crete incorporates to carry out ELF measurements and assess ELF field human exposure compliance. NIRL adopts all recent international and national measurement standards and European and Greek Legislation to provide measurement reports. Estimation of the measurements uncertainty is also presented to increase measurement scientific validity.

Experimental studies to assess the potential effects of the RF radiation on the prehatching development are often carried out. Some of them employ birds (Saito et al. 1991, Sisken et al. 1986, McRee and Hamrick 1997) and other small mammals (Larry et al. 1983, Larry and Connover 1987, Jensh et al. 1977, 1978) as experimental material. The power densities used in the above studies were either high of the order of mW/cm2, or even tens of mW/cm2 for short periods of time (Clark and Justesen 1983) or low for longer periods of time (Magras et al. 1998). The first category of studies deals with thermal effects causing congenital malformations, embryonic and fetal deaths (Larry et al. 1983, Larry and Connover 1987). The second category of studies deals with non-thermal (or micro-thermal) grave or mild effects (Tanner and Rommero-Sierra 1982, McRee and Hamrick 1997). Usually, they are under dispute since they cannot be replicated or statistically evaluated (Thuery 1992). Although that the existence of non-thermal effects is not yet widely accepted, nowadays they are of increasing importance. This importance is focused especially in the higher bands of the RF spectrum, which are going to find a wide application in the future and in which the organisms are not naturally adapted (Pakhomov et al. 1998). The purpose of this study was to review possible effects of pulse-modulated (PW) and non-modulated (CW), non-thermal, low power density microwave (Super High Frequency, SHF) radiation on experimental animals, especially on embryos and foetuses and to attempt an extrapolation to humans. Moreover, this work will attempt to explain possible physical mechanisms involved.