Inquinamento domestico da radizioni non ionizzanti

The aim of the study is to measure the electromagnetic fields pollution in some houses of Padova and to compare the values we obtained with limits of current law. The electromagnetic spectrum of interest is that of non-ionizing radiation, conventionally divided in low frequency (range between 0 and 300 Hz) and high frequency (range between 300 Hz and 300 GHz). In the range of low frequency radiation, the most prominent frequencies are 50 Hz, also called ELF (Extremely Low Frequency), used for the power lines that include high and medium voltage power plants, high voltage transmission lines, and substations. Inside the houses there are many sources of low-frequency radiation as well, represented by household appliances and electrical devices connected to low voltage line; recently, photovoltaic systems have been spreading in houses too. The main sources of external high frequency electromagnetic fields are fixed radiofrequencies transmitters like broadcast transmitters, mobile phone base stations, satellite systems, Wi-Fi systems, radars, etc. However, over the past 20 years the use of high-frequency devices which are very common in our houses, such as microwave ovens, cellular phones, cordless phones, Wi-Fi routers, baby-call monitors, energy saving light bulbs, alarm and anti-theft systems has increased exponentially. So we performed the magnetic field measurement inside the houses, evaluating the contribution of both internal and external sources. The measurements have been performed with the hand-held broadband analyzer of electromagnetic fields PMM 8053: using different probes, this instrument covers a range from 5 Hz to 40 GHz. For continuous measurements of low frequency electromagnetic fields, we used the Emdex II and Emdex Lite meters, which cover the frequency ranges between 40 and 800 Hz and 40 Hz and 1 kHz respectively. In order to evaluate the radiation emissions from household appliances, we measured the electromagnetic fields both near the sources and at different distances. On the contrary, to quantify the indoor pollution due to external sources (power lines, transformer stations, base radio-stations), we extended the measurements to 24 hours at least. The data obtained show that inside sources of high frequency electromagnetic fields produce quite high intensity electric fields, when measured nearby the sources (10 cm); these values in fact decrease dramatically with the distance from the source. However the values we measured never exceeded the limits set by the European Community Council Recommendation of 12 July 1999. It is useful to remember that this limit value only refers to radio frequencies effects experimentally tested, such as rising temperature in biological tissues. With regard to long-term effects from exposure to radio frequencies, the scientific scenario still presents contrasting results, so much so that IARC (International Agency for Research on Cancer) classified the use of mobile phones “possible carcinogenic to humans”. However, from a preventive point of view, it is useful to keep a "safety distance" at least when using household appliances with high emissions (eg microwave ovens), or that can be used for several hours a day, such as mobile and cordless phones or Wi-Fi systems. Data on low frequency electromagnetic radiations from household appliances do not show high values, with the exception of those observed in proximity of photovoltaic systems inverters (also over 50 µT). In this case too, the magnetic field intensity is significantly reduced, often close to or below one µT, at a distance of one meter from the source. In any case, the values collected measuring the magnetic fields are lower than the reference value of 100 µT established by the European Community in 1999. Similarly, this value is considered to be protective only for acute effects due to ELF, such as the induction of electric currents in the body. Again, in relation to long-term effects induced by electromagnetic fields, the scientific community has not drawn unambiguous conclusions, although many epidemiological studies evidenced an increased risk of getting myeloid leukemia in children living near the power lines and exposed to ELF levels higher than 0.3-0.4 µT. These findings have led the IARC to take an intermediate position, also classifying ELF as possible carcinogenic to humans. Measurements of electromagnetic fields indoor from external sources, such as mobile phone stations, are considerably low, compared both to the limit values and to the quality value of 6 V/m; moreover, they are negligible when compared to those emitted by wireless household devices, as mentioned above. On the other hand, the magnetic field values measured in houses placed under or near electric power lines, are not negligible at all: even if they are lower than the limit value of 100 µT and the attention value of 10 µT, they are close to the quality value of 3 µT. Once again, from a preventive point of view, keeping a safety distance from power lines, or laying them underground, may be useful to reduce the possible long-term effects associated with exposure to low frequency electromagnetic fields.