### I. Introduction

### II. Electromagnetic Fields

*Q*is the electric flux through a closed surface S,

*E*is the electric field,

*ɛ*

_{0}is the electric constant. Using Gauss’s law, electric fields around electrical lines can be determined. The equations for calculating the electric field around a power transmission line are described in [9]. Magnetic fields are created only when there is an electric current [1]. The magnitude of a magnetic field is proportional to the current flow through an electric line and not the voltage. As the current increases, so does the magnetic field. There is no relationship between magnetic field strength and voltage. Regarding electric transmission lines, it is not uncommon for a 20 kV electric line to have a higher magnetic field than a 115 kV line. High-voltage 400 kV lines can carry large currents and therefore may produce relatively high magnetic fields, but primary distribution lines with voltages less than 63 kV can produce fields similar to those measured around a transmission line if they carry enough current. Magnetic fields rapidly become weaker with distance from the source. However, they do pass through most non-metallic materials, so they are more difficult to shield. In the literature, magnetic field data are presented in either units of gauss (G) or tesla (T). A milligauss (mG) is equal to one thousandth of a gauss (G). One tesla is equal to 10,000 gauss. A micro-tesla (μT) is equal to one millionth of a tesla or 10 mG. A useful law is Ampere’s Law that relates the magnetic field around a closed loop to the electric current passing through the loop. This law is used to find the magnetic field generated by currents in highly symmetric geometries, such as an infinitely long wire or a solenoid. According to Ampere’s Law, the integral of B around any closed mathematical path equals

*μ*

_{0}times the current intercepted by the area spanning the path. Eq. (2) illustrates this concept [1]:

*I*is the current enclosed by that loop, and r is the distance from the center of the wire. Using Ampere’s Law, the magnetic fields of power transmission lines can be calculated [1].

### III. History of the Health Effects of EMFs

### IV. Software Package

### V. Calculation of EMFs around Electrical Distribution Lines

### VI. Results and Safe Margin Calculation

Environmental pollution in the form of electric fields is minimal and can be contained; therefore, the health effects relating to electric fields are negligible.

The magnetic fields of EDLs are a form of environmental pollution, and based on previous studies, living near power lines can be detrimental to human health.

Environmental pollution in the form of magnetic fields is much greater than environmental pollution in the form of electric fields and should be studied carefully.

Living close to EDLs may be hazardous.

Based on electric distribution design standards in Iran, there must be a minimum horizontal distance of 3 m between any part of a building and the closest 20 kV line and 1.5 m between any part of a building and the closest 400 V line. It seems that the safe distance standards for power distribution lines should be reviewed.