Scroll down and read Marius's comments. Very informative. Perfect ammo to shut down a crazy!
I see people have problems understanding radiation and how to quantify things.
I’m a electronic engineer and specialize in communication systems.
One thing I would like to make clear is that electromagnetic waves are transverse waves that exist of an electric field perpendicular to a magnetic field. Electromagnetic waves are not particles you can wipe of your face. It can be compared with sound waves, the energy only exist along as the wave exist.
Harmful radiation is another matter, yes harmful electromagnetic radiation does exist. It will depend on frequency and intensity. For a wave to be harmful it needs to cross a threshold of destructive intensity. The EU set the SAR for microwave to 2Watt per kg body tissue. To the non-technical person it means nothing leaving people vulnerable to absorb any information weather it is true or false, most people cannot quantify or make sense of such measures.
If you are exposed 50 000 lux of white light, it can damage your eyes, so we can say it is harmful electromagnetic radiation, but 300 lux of light in typical office will in your entire life not harm your eyes at all, still it is the same radiation but seen as harmless electromagnetic radiation.
Just a fun fact for people who think all electromagnetic radiation is bad, visible light is electromagnetic radiation in the visible frequency range which your eyes are very sensitive for. So for anyone who want to avoid all electromagnetic radiation should stay out of any form of light as well.
180dB of sound intensity can damage your ears in a very short period of time, so yes sound is harmful radiation at that intensity. But you can be exposed to 60dB of sound that is equal to a normal conversation and these potentially harmful waves that can damage your ears at high intensity will be harmless even if you are exposed to it for your entire life.
A 900km wind of a hurricane can destroy a city on moments, a 30km wind can blow for hundreds of years and cause no damage.
The magic word in all these examples including electromagnetic radiation is “threshold” the point where destruction of damage occur.
If you put your head in front of a 800watt magnetron like in you microwave oven it will heat up in seconds due to dielectric heating and will cause death in moments, if you stand under a cell phone tower (cell site) it will do absolutely nothing. The same as what sound of 20db (whisper) will do nothing to your hearing, same as candle light do nothing to your eyes and A 30km/h wind will not destroy your city.
The suns total radiation on the earth is 250Watt per square meter, standing directly under a cell phone tower measures at most 0.01Watt per square meter, the EU allowable safe exposure to microwave electromagnetic radiation termed as SAR Specific absorption rate is 2Watt per kg body tissue, worrying about cell phone tower’s radiation is like sitting in a sound proof room in dead quite silence worrying that the sound intensity will damage your ears. Or to lay outside at night watch the stars wile worrying of getting a sun burn.
LCD screens use liquid crystal to polarize the light, it’s only a filter controlled by electronic pulses, the filter polarize the light and control its intensity from a normal light source, its electromagnetic radiation is mostly in the visible light spectrum and of harmless intensity as you can see with your own eyes.
CRT tubes have small amount of x-ray due to the bombardment of electrons form the electron gun but is way below the harmful threshold to humans. Its normally way bellow 0.5 milliroentgens per hour (mR/h) (0.13 µC/(kg•h) or 36 pA/kg) at a distance of 5 cm.
Although I mostly don’t believe propaganda from speculation. I do have my doubts about the safety of long term use of cellular phones and microwave ovens since both these devices operate close to the acceptable safe limits and can have technical problems that can cause them to radiate above the acceptable safe threshold of electromagnetic radiation in extreme cases.
For computers there are some electromagnetic radiation, a CPU clocking on 2.4GHz will produce a microwave radiation since all alternating currents will produce electromagnetic radiation, it is way below any threshold of concern.
1) Sun Average radiation on the earth surface = 250W/m2
2) Leakage of a microwave oven at 5cm < 10W/m2
3) Radiation under cell phone tower < 0.01W/m2
Make sure the radiation is in harmful frequency spectrum or classification, make sure the intensity is of dangerous levels before concerns should be raised.
There are very well defines safety threshold levels and all accreditation and conformances to standard are subjected to these thresholds. I have been reading the most ridiculous claims made by people such as using fans to blow the radiation of your computer away which make as much sense of saying that I will blow your computers sound away with a fan or more accurately to blow the light (electromagnetic wave) away with a fan.
By the way, a fan also produce electromagnetic radiation. Some powerful fans can even cause interference on your TV set, that’s how much electromagnetic radiation do they produce, but although it can be high intensity it is on a safe frequency range. Gestures like wiping electromagnetic particles of your face. There is no such thing as electromagnetic particles. Right up to university physics there have never been such a particle electromagnetic propagation is a wave like sound. Wiping it of your face, makes as much sense as wiping sound or the white light of you bed lamp of your face. It is so easy to convince the public who cannot quantify or understand these measures to get them completely paranoid with these ridiculous claims.
I work with electromagnetic wave propagation every day, design electronic devices, antenna and radio systems, I work with accreditation systems and national and international standards in RF communication. I feel very comfortable in this pool of electromagnetic radiation as much as I feel comfortable in the pool of visible day light since daylight is electromagnetic radiation. I have no concerns since I know what it is, how it works and how to quantify the magnitudes of it.
But my advice to the public who have concerns are, if you are in a weak cell phone reception area, where the phones transmitter will work much harder, if your cell phone seem to have signal problems, or use a cell phone all day it is safe to use a speaker phone or head set since there are valid reasons to debate the long terms effects on this reasonably high microwave levels. Cell phones operate near the safe microwave (SAR) limits. if your microwave oven is old and rusty or door doesn’t close properly, please have it checked out. For most other domestic devices there are no scientific evidence of danger.
Nature it self surrounds us with radiation from nuclear radiation to electromagnetic radiation of the sun, these radiations are mostly much more like you can see in my three point table above. Most electronic devices only be detected with the most sensitive of test equipment and there is not reason to be concerned. You do not ever have to spend any money on devices that protects you against it no matter what sales talk these people try to use. Accept sun glasses and sun tan lotion if you pan on going out into the sun for long."
<message edited by Remorce on Saturday, February 11, 2012 8:22 AM>