William Pelet, of Otago Boys' High School, asks :-

Will a leather pouch for a cellphone prevent the possible human tissue damage caused by the radiation emitted by cellphones? If not, what can?

Martin Gledhill, a physicist offering independent measurements and advice on electromagnetic fields through EMF Services, responded.

While it is true that there is no definitive answer as to whether the radiofrequency (RF) radiation from cellphones can damage human tissues (and indeed, as in many areas of science, there will probably be lingering questions for ever), there is a broad consensus amongst scientists working in this area that it probably does not do any damage.

If you nevertheless do wish to reduce the exposures, a leather pouch would not help as it would absorb or reflect only a negligible amount of the radiation from the phone. While there are some pouches made of RF-absorbent material available, their usefulness has been questioned as they may cause the phone to operate at higher power than it would otherwise do - effectively cancelling any reduction in exposure, or affect the transmitting efficiency of the phone - giving an increase in power and a poor quality call.

Exposures reduce rapidly with increasing distance between the cellphone and your body, so the simplest and most effective way to reduce exposure is to either use a hands-free kit or put the cellphone on speaker-phone. Cellphones using the modern UMTS technology (also referred to in New Zealand as XT or 3G) have very effective control of their transmitting power, and generally transmit at around one-fiftieth of the power of the so-called "2G" (GSM) phones. Hence they produce a corresponding decrease in exposures. Typically the output power of a UMTS cellphone is lower than that of a cordless phone.

Don't forget either that if you are not on a call, the phone does not transmit, except for brief, occasional communications to stay in touch with the base station network.