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powerbook recharge radiation

Message #1 - Posted 2003/07/29 - Alan Evans and Lesley Greene

An article in the Guardian recently said that the EMF(?) given off by a laptop being charged was excessive, does any body know how Apple laptops fare in this?

And whilst on the subject of radiation....in all the excitement about bluetooth and airport I have not read anything that discusses the disadvantage or health implications of working next to radio transmitters as opposed to ehternet cables. Any information available anywhere?

Alan

A wise man learns from his mistakes..a lucky man learns from the mistakes of others

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Message #2 - Posted 2003/07/29 - Adrian Tuddenham

Alan Evans and Lesley Greene wrote:

An article in the Guardian recently said that the EMF(?) given off by a laptop being charged was excessive

E.M.F. stands for "Electromotive Force'. more commonly known as 'voltage' to the like of you and me.

If that is what the article really said, it is a load of ignorant bollocks. Whether there is some real scientific fact underlying the journaleese will probably never become clear.

Nothing whatsoever ought to be given off by a laptop on charge. There may be a magnetic field from the switched-mode power supply in the charger, but the frequencies and power levels would be relatively low and you don't normally get near enough to a charger to encounter any great field strength.

And whilst on the subject of radiation....in all the excitement about bluetooth and airport I have not read anything that discusses the disadvantage or health implications of working next to radio transmitters as opposed to ehternet cables. Any information available anywhere?

Slightly more believeable. Radio frequencies, especially high frequencies. can cause physiological effects if the power levels are high enough. (It is difficult to find any unbiassed and well-informed information, though).

Ethernet is specifically designed not to waste the signal power by radiating it and the frequencies involved are much lower - so the risk is as near zero as it could be. (Much higher risk of going to sleep whilst typing in bed and strangling yourself with the cable as you turn over in the night).

~ Adrian Tuddenham ~
(Change 'offline' to 'online' to reply) www.poppyrecords.co.uk

Message #3 - Posted 2003/07/29 - Alan Evans and Lesley Greene

Previously, Adrian Tuddenham wrote:

Alan Evans and Lesley Greene wrote:

An article in the Guardian recently said that the EMF(?) given off by a laptop being charged was excessive

E.M.F. stands for "Electromotive Force'. more commonly known as 'voltage' to the like of you and me.

If that is what the article really said, it is a load of ignorant bollocks. Whether there is some real scientific fact underlying the journaleese will probably never become clear.

Nothing whatsoever ought to be given off by a laptop on charge. There may be a magnetic field from the switched-mode power supply in the charger, but the frequencies and power levels would be relatively low and you don't normally get near enough to a charger to encounter any great field strength.

And whilst on the subject of radiation....in all the excitement about bluetooth and airport I have not read anything that discusses the disadvantage or health implications of working next to radio transmitters as opposed to ehternet cables. Any information available anywhere?

Slightly more believeable. Radio frequencies, especially high frequencies. can cause physiological effects if the power levels are high enough. (It is difficult to find any unbiassed and well-informed information, though).

Ethernet is specifically designed not to waste the signal power by radiating it and the frequencies involved are much lower - so the risk is as near zero as it could be. (Much higher risk of going to sleep whilst typing in bed and strangling yourself with the cable as you turn over in the night).

Sorry, I could not remember exactly what the article said, hence the question mark. I had the impression it was electro magnetic field or force and thought that was what EMF stood for. The paper was mislaid so I thought someone on the newsgroup might have knowledge if I worded it vaguely enough!

Thank you for the reassurance.

I intended to imply that I knew ethernet was the no risk option as opposed to the radio systems. I have been surprised that it has not been discussed or even mentioned in the reviews. In the mobile phone world it is at least detailed in the specification of telephones. The SonyEriccson people publish the fact that their T68i phone produces a quarter of the recommended maximum SAR level of radio frequency energy.

I had a student of telecommunications staying a couple of years ago who had said that there was no 'scientific' evidence to support the theory that mobile phones could increase the risk of brain tumours/other damage because all the research was funded by the phone companies and was directed to proving it did not occur. The advice at her University however (Munich) was do not use them in a car or coach or train and ask people you are travelling with not to either. They drew the parallel between the glass and metal box containing a microwave generator for exciting water molecules to heat food and the glass and metal box we drive around in containing a handheld communication device generating radio waves.

Alan

For instant decision making, flip a coin and base it on your sense of disapointment or elation at the result.

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Message #4 - Posted 2003/07/29 - Andrew Collier

Previously, LCDMan wrote:

I am sure there are studies to prove this one way or the other.

More likely both, unfortunately...

Andrew

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Message #5 - Posted 2003/07/29 - LCDMan

Previously, Peter Ceresole wrote:

Hihi,

I'm just a journo,

So EMF, Electromotive force or Electormagnetic field ? :-p

LCDMan

CannyCrow@xxhotmailxx.com no x please, i'm british.

Message #6 - Posted 2003/07/30 - Peter Ceresole

Previously, LCDMan wrote:

I'm just a journo,

So EMF, Electromotive force or Electormagnetic field ? :-p

Who knows? We don't even know what it actually said in the original- 'EMF' is a guess.

Peter

Message #7 - Posted 2003/07/30 - Peter Ceresole

Previously, Adrian Tuddenham wrote:

In the case of power lines, I understand that the electrical fields can increase the concentration of ionised particles around the line,

Electromagnetic fields or electrostatic fields? - Big difference.

I can't remember, but logic says electrostatic.

The first is tiny, the second is huge but easily stopped by almost anything, including a house wall or roof.

Sure, but in the case of a raised concentration of ions/radicals in the local atmosphere, once it has taken place electrostatic shielding ceases to be a factor.

Peter

Message #8 - Posted 2003/07/30 - has.mac

"Peter Ceresole" <peter@cara.demon.co.uk> wrote in message news:BB4D36CF96685877FD@0.0.0.0...

Previously, LCDMan wrote:

I'm just a journo,

So EMF, Electromotive force or Electormagnetic field ? :-p

Who knows? We don't even know what it actually said in the original- 'EMF' is a guess.

I don't normally like to touch this kind of discussion with a 10 foot barge pole, so.....doh, too late, I've started thinking about it now....

Concentrating on the original article, it sounds exaggerated and confused, the term EMF is defenitely wrong in the context used, it should be EM field, or EM radiation, where M stands for Magnetic. EMF is the abbreviation for electromotive force only. In terms of health, there is no danger from a laptop being on charge, unless it's resting on your lap and the extra heat generated fries your bits (a known feature of G4 powerbooks anyway).

In terms of radiated emssions testing, which all electrical equipment undergoes for type approval, then the charging situation can cause an increase in the normal emissions from the equipment due to the extra current being used, switch mode supplies and regulators working harder, etc. The equipment should have been tested while operating with all accessories, a standard worst case test is to measure emissions with a low battery and the charger connected.

I would like to see how they defined 'excessive' in terms of type approval limits. These limits are quite stringent, especially for non-transmitting equipment, to make sure one piece of equipment doesn't interfere with another. A failure against these limits is cause for concern in terms of the type approval status of the equipment, but not in terms of health.

As for Bluetooth and Airport, they both use low power (BT 1 or 2 mW, AP 1 or 2 W) in the 2.4GHz band, the same frequency as a microwave oven, which is one of the resonant frequencies of the water molecule, hence due to natural moisture in the air, has limited range and doesn't need to be licensed since there is little scope for long range interference, so I wouldn't worry about it. A microwave oven probably leaks more power than Airport deliberately puts out, so if you've already got a microwave oven, it's a bit late to start worrying.

To convince myself of all this I'm going to go and try cooking a sausage over an airport to see how long it takes.

has.mac

Message #9 - Posted 2003/07/30 - Tim Hodgson

has.mac wrote:

Concentrating on the original article, it sounds exaggerated and confused,

Has anyone actually seen the article? I had a quick search in the Guardian online archives - couldn't find anything.

TimH
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Message #10 - Posted 2003/07/30 - Adrian Tuddenham

has.mac wrote:

To convince myself of all this I'm going to go and try cooking a sausage over an airport to see how long it takes.

Reminds me of many years ago in the days before domestic microwave ovens were available:

A member of Bath Radio Club got hold of some sort of very powerful scrap industrial R.F. generator and managed to get it working.

He had heard that microwaves..

1) Could be used to cook things

2) Could produce sterility in men

.....and wondered if the lower frequency but higher power output of this equipment would do the same. If it worked, he could see possibilities at home for both uses as it would save him some money on both gas and contraceptives - so he devised a universal test piece, a raw sausage.

With the sausage in the output coil of the machine, he switched on. There was a pause while the valves warmed up, then the sausage exploded into fragments. When he reassembled it, he found that the sausage had been charred through the middle but was still raw on the outside.

He didn't take the experiments any further.

~ Adrian Tuddenham ~
(Change 'offline' to 'online' to reply) www.poppyrecords.co.uk

Message #11 - Posted 2003/07/30 - Adrian Tuddenham

Peter Ceresole wrote:

Previously, Adrian Tuddenham wrote:

In the case of power lines, I understand that the electrical fields can increase the concentration of ionised particles around the line,

Electromagnetic fields or electrostatic fields? - Big difference.

I can't remember, but logic says electrostatic.

The first is tiny, the second is huge but easily stopped by almost anything, including a house wall or roof.

Sure, but in the case of a raised concentration of ions/radicals in the local atmosphere, once it has taken place electrostatic shielding ceases to be a factor.

We've recently chewed this one over in another thread (you may have missed it) and my contention was that an *alternating* electrostatic field produces no net effect.

~ Adrian Tuddenham ~
(Change 'offline' to 'online' to reply) www.poppyrecords.co.uk

Message #12 - Posted 2003/07/30 - Peter Ceresole

Previously, Adrian Tuddenham wrote:

Sure, but in the case of a raised concentration of ions/radicals in the local atmosphere, once it has taken place electrostatic shielding ceases to be a factor.

We've recently chewed this one over in another thread (you may have missed it) and my contention was that an *alternating* electrostatic field produces no net effect.

Indeed. But from what I remember there is some kind of effect, even with a/c- probably in ionising the molecules in the first place. When I can hear the corona discharges near HT lines (and I can, especially in damp weather), I'm sure they must have a fairly marked electrochemical effect.

Peter

Message #13 - Posted 2003/07/30 - PeterD

has.mac wrote:

To convince myself of all this I'm going to go and try cooking a sausage over an airport to see how long it takes.

I would imagine if AP did cause any health problems, it would happen at far lower levels than those required to cook sausages.

Pd

Message #14 - Posted 2003/07/30 - Adrian Tuddenham

Peter Ceresole wrote:

Previously, Adrian Tuddenham wrote:

Sure, but in the case of a raised concentration of ions/radicals in the local atmosphere, once it has taken place electrostatic shielding ceases to be a factor.

We've recently chewed this one over in another thread (you may have missed it) and my contention was that an *alternating* electrostatic field produces no net effect.

Indeed. But from what I remember there is some kind of effect, even with a/c- probably in ionising the molecules in the first place. When I can hear the corona discharges near HT lines (and I can, especially in damp weather), I'm sure they must have a fairly marked electrochemical effect.

I see what you're getting at and, yes, this would occur with AC.

I once stopped in a layby one dark and misty night and was amazed to hear the continual corona discharge from the tips of the bushes and scrub alongside the road because some power lines crossed at that point.

I wonder how much worse this is than the ionisation from 'static' materials in a very dry centrally-heated house?

~ Adrian Tuddenham ~
(Change 'offline' to 'online' to reply) www.poppyrecords.co.uk

Message #15 - Posted 2003/07/31 - Adrian Tuddenham

Alan Evans and Lesley Greene wrote:

I had a look on the Guardian site and found the offending article:-

OK. I'll rise to the bait...... (theirs, not yours)

"Plant life: Peter Smith is a medical consultant at the Hale Clinic and he works with sick buildings syndrome, testing patients for electromagnetic stress.

I have never heard of any connection between electromagnetism and 'sick-building syndrome'. Peter Ceresole's suggestion of ionisation from electrostatics seems much more plausible.

He says that spider plants and geraniums are brilliant for helping

...perhaps...

with "off gassing" which comes from carpets, paints, furniture

.....yes.....

and all
things electric.

..... but not *because* they are electric - merely because they are made of plastic, paint etc.

He points out that photocopier engineers are now wearing gloves and masks.

To prevent inhalation of toner dust (microscopic polystyrene particles) Nothing whatsoever to do with magnetic fields.

"Make sure you're 5ft away from the back and sides of a VDU," he says. He also warns against working on a laptop plugged into the mains. "A charging laptop gives off the biggest electromagnetic field," he says.

I think the time has come to get out my test set and do some measurements - because I can't believe there should be any significant magnetic field from a laptop on charge. It has no mechanism for producing it.

"The lowest
radiation is from a laptop running on a battery. A VDU is somewhere in between." The best, he says, are flat panel monitors."

...and all of them are within the accepted limits which aren't, in any case, based on any hard facts or evidence of real risks.

The plugged in laptop comment was quoted to me without the context. I had taken it to mean that it was the biggest in a global sense not just relative to a VDU, hence my original posting...sorry!

You obviously got the gist of it dead right - just a pity the article was dead wrong.

~ Adrian Tuddenham ~
(Change 'offline' to 'online' to reply) www.poppyrecords.co.uk

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