Naked Science Forum
Non Life Sciences => Technology => Topic started by: thedoc on 08/04/2013 13:30:01
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Enver Hassim asked the Naked Scientists:
I work for a couple of public schools in Cape Town, South Africa and would like to know what risks are there installing cellular telephone towers at schools.
I believe that while it is a good way for public schools to generate funds, it should not be done at the expense of the health and well-being of students (and staff).
Regards,
Enver
What do you think?
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Unless all doubt has been removed whether such Towers can cause any harm to humans then I think its a bad idea to place such constructions in the vicinity of societies must vulnerable members. I have not read much data about them but my unscientific gut feeling is that they could affect us somehow. Will be interesting to read what more people think on this and hear the NS pod-cast on this one.
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One controversial executive at an Australian telephone company once stated that he would prefer the mobile towers to be built in his child's school playground, because then the radiation would go out over their heads.
Apart from the obvious self-interest, he does have a point.
The radiation pattern from the mobile phone tower is designed to project the most energy out at the horizon, where the mobile users are further away, and the signals are very weak (due to the inverse-square law for radiation). Close users don't have so much attenuation, and so only a small amount of power is directed down to the ground. The mobile antenna is designed to be quite directional.
The more recent 4G technology is designed so that multiple antennas operate as a team to control the transmit power in an even more directional manner, so a transmit beam would be directed downwards only when there is a mobile user under the tower. (There are still the general housekeeping functions like inviting mobile phones to register with the cell, which are designed to be accessed by users throughout the cell - but most of the energy is still directed out to the horizon).
The power level from the mobile tower is far less than the power you would receive from playing in the sunlight (with the added distinction that the sunlight contains a fair UV component, which is a known carcinogen).
Caution is always wise with any new technology, but WHO has been searching for evidence of harm from mobile phones, without success (they are still keeping a watching brief).
It is possible for us to do an experiment to check this ourselves by watching the received signal level on our mobile phone while walking towards a mobile phone tower. But I wouldn't recommend climbing a ladder to put your mobile phone directly in the main beam from the antennas!
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There there no proven mechanism for harm at the levels of radiation permitted by law, and in any case, field strength decreases as 1/d^2. (Installation engineers are typically advised to avoid an exclusion zone of typically 3meters immediately in front of big cellphone-tower antennas). I agree with evan_au, that yes, if mounted on the roof then nearly all the signal will go out over their heads anyway.
Another consideration is that the nearer the base-station to the users it serves the lower transmit-power the handsets have to use during conversations... (and the longer the battery/talktime will last)
How many people that "worry" about phone base stations have a WiFi router (100mW, typ) sat right next to their computer/bed/sofa? Remember the 1/d^2 rule...
We have a base station at work and if you deliberately go up the staircase in the building opposite, so about 10metres in front of the antenna and only slightly below (about 1 floor down), you get about -26dBm RSSI on phone (I admit I'd be less happy having my desk right there!), compared to around -80dBm for a typical "good" phone signal a mile or so from base. But even another 20-30metres away, off axis, the signal is a much lower -55dBm or so. (note dBm is a log scale!). Point being, the antennas are very directional, and in a more normal rooftop installation, the signal really can be expected to go out "over your head" - think of it a bit like the beam from a lighthouse!
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Most cellular 'phone systems work around 600Mhz - in the region of 1m wavelengths. Electromagnetic radiation doesn't have the energy required to displace electrons (i.e. what we'd call "ionising radiation") until you get up to ultraviolet light (that's why it causes sunburn) up at around 400nM wavelength - around 21 octaves higher frequency. That's why TV/Radio/mobiles DON'T cause cancer.
Now that's not to say EM radiation can't cause trouble at lower frequencies, but if it does it's chiefly from inducing heating effects; microwave ovens that operate in the 1cm wavelengths. Radar technicians and broadcast engineers have a device that monitors their body temperature as you may not notice the slow increase before it becomes dangerous (the frog in slowly boiling water).
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Well, I don't think there's a significant risk from the radio waves, but if one had been installed at my old school, it would probably have been stolen.
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There might be a bit of a danger with kids climbing them and falling or with icicles falling off in the winter !
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I guess they aren't as they are bound to emit radiation which is completely unhealthy for children so i am pretty much against the installation of cellular towers in schools.
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The principal danger to children from mobile phones is from inattention to the environment (they are banned on airfields, not because they interfere with avionics, but because they encourage groundcrew to walk into propellors whilst ordering pizza. Propellors are expensive.). Kids on the phone tend to step into roadways or fall off things.
The intensity of radiation absorbed in the brain from the handset is orders of magnitude greater than that received from even standing next to a repeater mast.
Mobile phones are used for text bullying - an increasing cause of pupil suicide - and paedophiliac grooming.
Mobile phones are a principal target for juvenile thieves.
You can get beaten up in order to steal your new phone, or because you have an old one.
Having a handy camera that can transmit photographs means that you don't have to learn to observe or describe anything. Concentrating on recording an event means that you don't actually enjoy it.
By all means have the masts on school premises: they are harmless. But don't let anyone under the age of consent have a mobile phone.
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This is always a good pub debate when I state that putting a cell tower on a school is the best place for it.
1. The power from the tower is negligable in terms of radiating the kids. It's too far away.
2. Their phone will be on minimum power as that's how GSM works with close signals.
3. As a result the power induced in their heads from their own handset is far less that if they were in contact with a tower miles away forcing their handset to go full power and induce that in their heads.
It is that simple.
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I agree with alancalverd - it's the mobiles that are more dangerous than the masts. Don't get me wrong I would be lost without mine :) but I don't understand the need for children to have them.
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Children have them for the same reason that they have fancy plimsolls for prestige also the parents can continually check-up as to where they are and avoid the accusation that they are letting them fall into the hands of the vast number of paedophile's that are hunting for children
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Ah yes, I forgot to mention paedophiles. Best way to groom a kid is via mobile phone text.
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keep the safe distance, more than 100 foots would be safe for childs.
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I forgot you have to use double think with regards to mobile phones and paedophiles the kids must have them so that you can check up that that they are not visiting dangerous places like parks or malls but they must not have them in case they are groomed !!
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If there is any risk (no proof after many years of use now all over the World) it will be from the phone next to the head. The power/sq metre from a base station even a very close one is very low. As many phones radiate less power if they are receiving a strong signal (less is needed if the base is close) siting a base station near a school could the best thing you could do.
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Most cellular 'phone systems work around 600Mhz - in the region of 1m wavelengths. Electromagnetic radiation doesn't have the energy required to displace electrons (i.e. what we'd call "ionising radiation") until you get up to ultraviolet light (that's why it causes sunburn) up at around 400nM wavelength - around 21 octaves higher frequency. That's why TV/Radio/mobiles DON'T cause cancer.
Now that's not to say EM radiation can't cause trouble at lower frequencies, but if it does it's chiefly from inducing heating effects; microwave ovens that operate in the 1cm wavelengths. Radar technicians and broadcast engineers have a device that monitors their body temperature as you may not notice the slow increase before it becomes dangerous (the frog in slowly boiling water).
This assumes that the only possible way for EM radiation to cause cancer is to ionize matter in cells. That's incorrect. There are other ways it can conceivably cause cancer. Em radiation has an alternating magnetic field. Such a field can effect the action of enzymes and interupt their process thus interupting cellular metabolism. That can concievably cause cancer.
However the magnitude of the magnetic field inside cells is so small as to be neglegible even if the radiation impinges right onto you. Never the less it'd be wise to look all this up and study it. However there is no relationship between cell phones so far. I seriously doubt there ever would be. Especially in a school yard for the reasons stated. There are much more dangerous things to worry about. I personally wouldn't worry about it if it was my children going there (if I had children that is).
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Prof Moulder of The Medical College of Wisconsin is possibly the World's number one expert on the subject. He concludes mobiles are dangerous . .. people have accidents when driving. But I wonder how many lives have been saved when folks can get though to the emergency services quickly??
http://www.mcw.edu/radiationoncology/faculty/johnmoulder.htm
There are some really loony folk out there who have illogical fears and there are sharks who prey on them. BBC did (not too scientific) experiment. It filled an hotel with folks some of whom claim to be electro-sensitive. They put an temporary mobile base in the car park. One lad felt so ill he had to go home. At that point the base hadn't been powered.
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A new study has found that childrens absorbs more microwave radiation than adults. Don't forget also that microwave radiation is a Class 2B (possible) carcinogen...
http://www.sciencedirect.com/science/article/pii/S2213879X14000583
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On a weight for weight basis I suspect that children also emit more microwaves than adults.
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In modern technology world cellular telephone towers is a safe installing in school. This is completely approaching by school board. I appreciate with because it is well being of students. Completely we use the sunlight for this project.
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In modern technology world cellular telephone towers is a safe installing in school. This is completely approaching by school board. I appreciate with because it is well being of students. Completely we use the sunlight for this project.
I disagree. Installing microwave emitting radiation systems in public places is irresponsible. Just like cell phones, microwave radiation is carcinogen and may cause neurological problems in susceptible persons.