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The use of devices emitting electromagnetic fields (EMF) ranging from static to microwave frequencies has significantly increased in the past two decades. Their presence has affected almost every aspect of living (home, traveling, school, college, work …). In the case of low frequency fields (0 Hz to 100 kHz), attention is focused on the systems for transmission, distribution and use of the electrical energy. For the high frequency range (100 kHz to 300 GHz), the main sources up to now have been Radio and TV transmitters and the cellular mobile communication systems. Their functions will be enlarged by additional services (mobile video and television) in the future. Generally, new artificial sources include different exposure scenarios with regards to body site, duration of use, target population, and also to simultaneous exposure to complex multiple frequencies spread over a potentially large frequencies range(1).
Significant public and media concerns are expressed about increases in EMF exposure of people and its potentially adverse effects on health, particularly children health. These associations are not explained by any confirmed biological mechanism and there are doubts as to their causal nature, as the available evidence is inadequate to make sound scientific conclusions. Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) points out that scientific studies still fail to provide support for an effect of EMF on self-reported symptoms, but indicate that the expectation or belief that something is harmful may play a role in symptom formation. Further epidemiological and laboratory investigations are needed(2).
In order to evaluate population exposure, knowledge of the field levels is very important. Measurements are basic both for the verification of the results obtained through the use of numerical models, and for the evaluation of the field levels when the sources are unlikely to be simulated because of their number, working condition, and complex distribution. The result of a measurement, given by the indication of the instrument, is only an estimate of the measurand (the subject to measurement) and thus it is complete only if associated to a statement of uncertainty parameter that characterizes the dispersion of the values that could be reasonably attributed to the measurand. All the components giving an uncertainty contribution should then be identified with reference both to the measuring instruments used and to the measurement procedures and conditions; that cannot be a priori dismissed(3). The evaluation of uncertainty becomes crucial when comparing a result of measurement with a field limit value fixed by a standard(4).
Besides the uncertainty associated with the use of a field meter, other contributions also have to be considered when evaluating uncertainty of a field measurement. These contributions depend both on the measurement procedures and conditions and on the characteristics of the field source.
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