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Position Paper on Electromagnetic Radiation in the Student Environment

In November 2010, a position paper on the subject of "Electromagnetic radiation in the student environment" (Hebrew)  was published.  This was formulated at the request of MK D

Table of Use of Frequencies

Frequency Band Applications of the Electromagnetic Spectrum

Source: ITU-International telecommunication Union: Recommendation ITU-R V.431-7 

Nomenclature of the Frequency and Wavelength Bands used in Telecommunications

(ITU Legal Affairs Unit - Table 1 reproduction permission, Hebrew translation, July 25, 2014)

 

Artificial Light Sources

The development of artificial light based on electric energy sources began at the end of the 19th and early 20th centuries.  In developing artificial lights, the technological effort is aimed at producing light that will resemble natural daylight (sunlight).  Artificial light is measured in two ways – the specific frequency range of the source and the strength of illumination, measured in lumens.  Artificial light can be classified into three main sources, in accordance with its developmental generation and the technology that enabled its existence.

   

Evening sunlight at the seaside

Evening sunlight at the seaside

 

First generation – bulbs based on heating of a wire filament (incandescent lamps) or an arc

A standard modern incandescent lamp is composed of a glass bulb containing a coil of metal wire, such as tungsten (W), in a vacuum.  Incandescent lamps emit non-ionizing radiation in the visible light range and do not usually emit radiation in the ultraviolet (UV) range, except in extreme conditions of very high power. Additionally this type of lamp also emits invisible infra-red non-ionizing radiation which is felt as heat.

 

The halogen lamp is a type of incandescent lamp filled with a halogen gas such as iodine (I) or bromine (Br).  It emits visible light and a little UV light.  As UV is ionizing radiation  that may cause, with prolonged exposure, burns and skin cancer, prolonged close exposure to halogen lamps should be avoided.

 

The carbon arc lamp comprises two tubular carbon (C) electrodes connected to an electric voltage source in the open air.  This lamp emits visible light and also UV radiation.  Because of its high intensity it is forbidden to look at its light source directly.

     

Quality incandescent light bulb, after Edison

Quality incandescent light bulb, after Edison

 

 

Second Generation – Gas discharge lamps

Fluorescent lighting is based on electric discharge of a gas (mercury) leading to emission of high-energy photons (usually UV), that impact the fluorescent coating of the bulb, producing visible light.

 

The type of radiation emitted by fluorescent tubes and compact fluorescent lamps (CFL) includes, in addition to visible light, a small amount of UV radiation in the UVA range (315-380 nanometers), and even shorter wavelengths (higher energy) in the UVC range.

 

Exposure to UV radiation from CFL lamps containing mercury may be reduced by distancing the lamps from the user by 30 cm or more.

   

Compact fluorescent lamp (CFL)
                                                                                                                          
 		  Compact fluorescent lamp (CFL)

 

Third generation – Light-Emitting Diode (LED) lamps

A light-emitting diode (LED) consists of a semiconductor  that has undergone doping.  An electric current passing through the diode excites the atoms to high energies.  When the atoms return to lower energy levels, energy in the form of photons in the visible light range is released.

 

LED lamps emit visible light and do not emit UV radiation.

 
  

Modern LED lamps

Modern LED lamps

 

 

Multiphase Alternating Current (AC)

A combination of several alternating currents (*) operating in parallel at different time periods (phases) depending on the definite time offsets of the electric power source (AC power). Multi-phase systems are useful in industry and for high efficient long distance transportation of electricity via high-voltage lines. Multi-phase system can be of 2,3 or more phases.

(*) See definition - AC

English

Direct Current (DC)

An electric current, ie the unidirectional flow or movement of electric charge carriers (electrons or ions, or both), which flow uniformly, from the negative pole of an electrical power source (eg a battery) via an electric circuit to its positive pole, or vice versa (positive pole to the negative pole). When the electrical power poles are fixed, the positive pole is always positive, and the negative pole is always negative. Therefore, the direction of the electric current does not change.

English

Alternating Currents (AC)

An electric current, ie the movement of electric charges (electrons or ions, or both) that changes direction cyclically following a periodic change in the polarity of the electric power source (voltage), (current frequency).

Number of cycles per second is measured in units of Hertz. (HZ)

AC technology was developed by the Serbian physicist Nikola Tesla. AC is commonly used in applications where high power is required. 

English

Infrared, Visible Light and Soft Ultraviolet Radiation – Introduction

Non-ionizing electromagnetic radiation covers a wide range of frequencies – from extremely low frequencies (ELF), which include frequencies utilized in the electricity grid, through radiofrequencies (RF) to soft ultraviolet (UV).

 

An important range of non-ionizing radiation is the one which includes infrared, visible, and soft ultraviolet light.  This range of frequencies, especially visible light, is very important to daily life.  Radiation in these frequencies may be from natural or artificial sources.

Cellular Base Stations – Cellular Sites

A cellular communication base station is an apparatus for transmitting and receiving electromagnetic waves in the radiofrequency (RF) range and it is the site through which cellular devices communicate with communication systems deployed throughout the world. The antennas of a cellular base station are the source of radiofrequency radiation that is transmitted through the spatial volume of the cell that it serves.

Cellular Communication Network Technologies

 

Israeli Policy on the Use of Mobile Phones in Schools

 

Mobile phones are being ever-increasingly used by children and adolescents.  Beyond the concern about the possible hazardous health effects of using this technology, the use of mobile phones has social and behavioral consequences that apply within schools.

 

In the school environment there are a number of sources of exposure to non-ionizing radiation, among them the power grid, access points for wireless Internet connection, and mobile phones.  While the power grid and wireless access points to the Internet are part of the school infrastructure, mobile phones are a source of radiation that in principle can be controlled, and are the responsibility of the user (the student/ the staff).  Moreover, in contrast to radiation from the power grid and the wireless Internet, most of the exposure to radiation emitted by the mobile phone applies to the user him/herself, because of its proximity to the user's body.

   Pupil Sending Text Message On Mobile Phone In Class

 

It should be noted that the student population, children and adolescents, is unique in its characteristics.

 

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