Non Ionizing Radiation in Urban Areas: Modeling of Electric Field Intensity from TV Broadcasting Using Multivariate Statistics Regression

Abstract

The Electric Field Intensity is one of the fundamental parameters to assess the exposure of human beings to Non-Ionizing Radiation (NIR). Although the major concern of environmental control bodies is with mobile telecommunication systems, this work highlights the attention which should also be given to the radiation emitted by television broadcast towers, which utilize higher power levels with continuous emissions.Measurements of downlink far electric field intensity with frequency ranging from 30 MHz to 3 GHz were made in a survey of 160outdoor points spread across all the 170 km2 area of Natal (a city of about 853.000inhabitants in northeast Brazil). The results obtained indicate that in 73.6% of the sampled outdoor points, the highest downlink electric field intensitiesmeasured were originated from TV broadcasting services, compared to 20.1% from Mobile SystemsTowers, 6.3% from Frequency Modulated Broadcasting and 0% from WLAN (IEEE 802.11bg). Based on these findings, a model is presented to estimate the intensity of the mean electric field at any given point of the city’s urban area generated by TV radiation emissions at VHF and UHF bands. Four distinct areas of the city were considered, basically adjusted to the azimuths related to the main tower concentration place. The modeling was done using the Statistical Multivariate Regressiontechnique, the Electric Field Strength was the dependent variable, the independent variables were the Distances of points to the transmission towers. Database was used with samples of measured values of Electric Field and their Distances to the TV transmission towers. The solution reached to estimate the electric field can be adapted for use in other cities. Detailed mapping of the electric field intensitiesmayensurebetter preventive conditions to monitor the degree of NIR exposurein each area and simplify evaluation procedures for the licensing of telecommunication stations.