Mobile phones

Mobile phones

Does the intensity of radiation emitted by a mobile phone increase during charging? Is there a difference between the radiation emitted by the device and that emitted by the transformer?

During the process of charging a mobile phone while not being used for communication or other application, exposure to radiation may originate from two sources:

  1. Exposure to the magnetic field of the electric grid at extremely low frequency (ELF) resulting from the operation of the transformer during the charging process.In the older generation of transformers the strength of the magnetic field was elevated –up to a few dozen milligauss, over a radius of a few dozen centimeters.Modern transformers have built-in electromagnetic compatibility (EMC), which reduces the strength of the fields to negligible levels relative to the levels recommended by the Ministry of Environmental Protection.

  2. Exposure to radiofrequency radiation (RF) emitted by the device itself.Even with the device in passive mode, there is routine activity of wireless radio transmission.

  3. Once every few seconds, preset detection pulses are emitted at a certain frequency to a nearby cellular station, for the purpose of localization and identification of the device in the cellular communications network.

  4. Smartphones in which applications have been installed may allow routine transfer of data between the mobile phone and the nearby station, or to a domestic or local Wi-Fi network to which the device is connected.

It should be emphasized that the level of exposure to non-ionizing radiation decreases significantly with increasing distance between the human body and the source of radiation.  Consequently, it is recommended that radiation-emitting devices be held away from the body when possible, and that during charging the devices be placed at a distance of at least 0.5 meters from the body.



Do Mobile Phones Emit Radiation When in Flight Mode?

In flight mode the communication system of the mobile device is disabled – it does not transmit or receive, and therefore does not emit radiation.


 In most devices, the operation of flight mode disables both the cellular and the Wi-Fi communication functions. However, in some devices the Wi-Fi communication mode may not turn off automatically when switching to flight mode, and it is therefore recommended to check whether the mobile communication display indicates that these functions (cellular and Wi-Fi) have shut down.



What is the level of exposure to radiation emitted during the use of mobile phones on trains (and other enclosed spaces), and what risk to passengers does this imply?

This question refers to the use of mobile phones in enclosed spaces in general.  Anyone in an enclosed public space such as an elevator, a bus, a railroad car or an airplane, in the presence of people conversing on mobile phones, is exposed against his will to noise and radiation, especially when the enclosed space is covered with surface materials that reflect sound and radiation, such as aluminum or steel.


Illustration: People using mobile phones on train


Nevertheless, the degree of exposure to radiation emitted by mobile phones in such enclosed public spaces is not uniform, since it depends on the nature of the space, the material enclosing the space, and its location.


The cellular device regulates its strength of transmission to the minimum required to enable it to make reasonable contact with the nearest base station.  In enclosed spaces such as railroad cars, buses, elevators and shelters, the radiation emitted by the cellular device does not spread out, but is reflected, especially if the enclosing material includes aluminum or steel surfaces.  Also, if the radiation from the nearest base station does not penetrate the space (due to shielding), or if the antennas are spread wide apart (e.g. as in interurban travel outside populated areas), the device 'strains' to reach the nearest base station; it must transmit at full strength, and emits its maximal level of radiation.  Such areas may be readily identified through the level of reception indicated on the mobile phone's screen.   It should be noted that under such conditions, people in the vicinity of the user, as well as the user himself, may be exposed to radiation.  It should also be mentioned that during train travel of relatively long duration, the extent of exposure to radiation may increase.


The health risk arising from exposure to mobile phone radiation in trains has not been studied specifically, and one must therefore relate to exposure to radiofrequency (RF) radiation in general.

The issue of potential health risks resulting from exposure to non-ionizing radiation has preoccupied the scientific world and policy makers for many years, especially since the mid-1990s, with the introduction of cellular technology.  Existing scientific knowledge is still not sufficient to determine whether non-ionizing radiation is harmful to heath.  Studies in this field have shown that higher powers of radiofrequency radiation cause heating of the body, to an extent dependent on the distance from the source of radiation.  As for lower powers, health effects are still being studied, and no unequivocal conclusions have been reached.  In 2011 the World Health Organization classified radiofrequency radiation as 'possibly carcinogenic to humans'(Category 2B in the list of carcinogens).  The practical significance of this classification is that educated use should be made of mobile phones and other non-ionizing radiation-emitting technologies, to reduce the exposure to the radiation they emit.


Consequently, most countries and authorities have adopted the precautionary principle with regard to exposure to radiofrequency non-ionizing radiation.  This principle supports reduction of exposure to the lowest possible level, while striking a balance between the needs of advanced technology and the protection of human health.


Also, it should be noted that environmental exposure of passengers on a train, caused by others using their mobile phones, is much lower than the personal exposure to a mobile phone user holding the phone close to the body.


Do anti-radiation stickers on mobile phones reduce radiation exposure?

As a rule, electromagnetic radiation may be blocked or distorted by partial or total absorption or deflection.


A sticker may also fulfil the function of absorption or deflection of electromagnetic radiation, partially or completely, depending on the physical properties of the material of the sticker.  Hence, applying a sticker of a certain composition and size may alter the configuration of the electromagnetic waves going from the mobile phone to the user.  However, the profile of absorption and deflection of the sticker cannot be gauged, nor whether it comprises materials or technologies that are effective on electromagnetic waves.  This also depends on the radiation curve, and on the frequencies and technology of the specific phone in question.  It is thus not possible to assess the effect of the sticker on protection against radiation.


To obtain a clearer picture, specific studies on assessments of the profiles of action of specific stickers should be performed.  It should be noted that the sticker may even increase the dispersion of radiation towards the user.


Consequently, it cannot be determined whether the user of stickers in general actually reduces the amount of electromagnetic radiation.



How can one reduce the levels of radiation exposure while using mobile phones?

The easiest way to reduce the level of radiation exposure is by holding the phone away from the body!


In general, the guidelines issued by the TNUDA center and the Ministry of Health are based on the precautionary principle, while maintaining a balance between the technological needs of the society in Israel and the degree of caution required to safeguard health.  The main recommendations are:

  • Using a loudspeaker/personal hands-free accessory or earphones (not wireless) or any other device that keeps phone away from the body while talking.

  • Restricting talking in locations where reception is weak (where base station are relatively scarce or reception is screened off, as in elevators or trains).


Is it safe to use a hands-free accessory for the mobile phone while driving?

This question refers to two different issues: "Does using the accessory pose a health hazard through the radiation emitted from the phone?" and "Does using the accessory while driving increase the risk of accidents resulting from the driver's diminished concentration?"  Regarding protection from radiation, using a hands-free accessory is preferable to holding the phone next to the head.  On the other hand, as to the safety of driving, it appears that the use of such an accessory also poses a real risk.  Recent studies have shown that the degree of distraction resulting from phoning while driving, whether using a hands-free accessory or earphones, is similar to that when using the phone placed next to the ear.  This inattention may substantially increase the risk of accidents so that on the whole it is recommended to refrain from talking on the phone while driving. 


Studies have shown that the effect of a phone conversation on the driver's behavior is similar to or even greater than that due to driving under the influence of alcohol.  Even more dangerous situations occur when the driver's sight is diverted from the road to the phone, as when tapping a number on the phone or answering a text message.  Such activities should be avoided altogether.  It must be emphasized that young drivers, for whom driving is not yet a sufficiently automatic activity, are most influenced by diversion of attention through using a phone while driving.



Is it safe to use a mobile phone in elevators?

Elevators are usually built of metal that does not allow radiofrequency waves from the phone to be transmitted outside the elevator to the antenna/base station that receives them.  Consequently, the phone 'strains' to contact the external network while emitting its highest level of radiation.  In addition, a phone conversation cannot usually be conducted normally and the user will experience reception problems.  The screening off of radio waves in the elevator exposes the user to the highest level of radiation from the phone.  It is important to note that in such a situation persons in the elevator may be passively exposed.  It is thus recommended to refrain from using mobile phones while in elevators (usually a short period of time) and to postpone the call until after leaving the elevator.


What is the difference between wired earphones and Bluetooth headsets?

Bluetooth is a communications channel that transmits at high frequency in the range of non-ionizing radiation. Bluetooth has several applications, including headsets that operate as a sort of personal area network (PAN).  Through synchronization of communication between the Bluetooth device and the user's mobile phone, the communication channel is maintained, even when the mobile phone does not receive or transmit calls.


Radiation from the headset in the Bluetooth device is much lower than the level of exposure recommended for non-ionizing radiation (maximal level of exposure recommended by the Ministry of Environmental Protection for radiation in the 2.4 GHz range is 3 watts/sq.m and 1 watt/sq.m for continuous and prolonged exposure).


Moreover, the Specific Absorption Rates (SAR – amount of radiation absorbed by the body) of the Bluetooth headsets are lower than the SAR values of mobile phones (SAR values of mobile phones range between 0.4-1.2 watts/kg, compared with SAR values of Bluetooth headsets, which are in the range of 0.01 watts/kg or less).


Bluetooth device

Bluetooth device


However, since the headsets are placed on the ear, and some Bluetooth users append them for several hours of use, exposure to radiation is more prolonged.

Hearing with bluetooth headset

Hearing with bluetooth headset


In contrast to the Bluetooth headset, hearing with wired earphones is not associated with radiation exposure.  These serve as a bridging element to the device that transmits music, for instance, such as radios, mobile phones, etc.  The sound signals are converted to electrical signals at very low intensities.  These signals reach the earpiece of the earphones, where they are converted back from the low electrical current to produce vibrations in the earpiece, which we receive as sound.  It is these low frequency currents that are of concern.  The current produces a magnetic field around itself, but in the case of earphones the currents are weak and produce weak magnetic fields.  Concern has been voiced over the use of regular earphones, based on the erroneous claim that the wires attached to the earphones serve as antennas, thus magnifying the transmission straight into the ear.  This claim was tested through assessment of radiation in the wires of the earphones, and has been disproved.

Hearing with wired earphones

Hearing with wired earphones


Do cellphones emit more radiation inside cars?

As a rule, cellphones increase the strength of their emissions when there are poor reception conditions, with corresponding increase in the level of radiation exposure in their vicinity.


Radiation exposure levels from cellphone use inside cars are higher than from use outside cars in open areas, but the difference is not great. This is because of the relatively small effect of cars’ structures on reception conditions inside them.


The reason for this is that because cars have a relatively large area of windows, which do not constitute a meaningful obstacle for radiation. Also, cellphones are usually located next to windows and their use in cars is usually via a hands-off speaker, which also has the advantage of distancing the phone from the user’s body thus significantly reducing the level of exposure.


It is noted that there is reflection of radiation from the car walls and from other metal objects inside the car, but their contribution to an increase in radiation levels is not great, because of the presence of plastic and upholstery and because of radiation dispersion and absorption effects.



Is there a difference in terms of radiation exposure between using text messages and talking on cellphones?

One of the recommended ways of reducing exposure to radiation when using a cellphone, is to use text messages (and not talking).

Sending a WhatsApp message (using words) involves sending information and transmission during a relatively short time than a cellphone conversation, and also involves distancing the cellphone further from the head and the body than does a cellphone conversation, and as a result there is significant reduction in the degree of radiation exposure.