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Thread ID: 46983	2004-07-12 02:21:00	Radiation from 17" Imri Accuvision 710A monitor	braindead (1685)	Press F1

Post ID	Timestamp	Content	User
251626	2004-07-12 02:21:00	This is my main work monitor (about 2 years old) and I'm wondering if the hours I spend around it may be bad for my health. Is there any way of finding out how much radiation might be aimed downwards, slowly 'microwaving' my legs over a period of years? I'm no longer worried about my fertility. Are there "bad" and "good" monitor brands as far as radiation goes? Thanks :: John	braindead (1685)
251627	2004-07-12 04:45:00	There is no "radiation" as such from computer monitors, but if you can bear with me for a while I'll locate a previous post that explained all of this and repost it for you. Cheers Billy 8-{)	Billy T (70)
251628	2004-07-12 05:12:00	Here you go John This is a cut, paste and edit from a couple of my previous posts: As far as emissions are concerned, all modern monitors conform to the Swedish MPR and American TCO emission standards, which in simple terms means that provided you stay at least 50cm from the screen there are no emissions to speak of . I have checked many modern screens and have never found emission levels higher than MPR/TCO . The principal measurements are made on the electromagnetic emissions from the scan coils at ELF and VLF frequencies . Note I use the word emissions, that is because the term "radiation" is extremely emotive and conveys the spectre of ionising radiation . Ionising radiation comes from radioactive materials, beta & X-rays, cosmic radiation from space, radon gas from the earth etc and generally speaking is "not a good thing," however, whether you like it or not, you are constantly exposed to ionising radiation by virtue of your existence on this planet . There is nothing in a CRT monitor capable of generating ionising radiation, and even X-ray emissions are below background radiation levels . To be specific, X-radiation from CRT monitors is measured as the kerma rate in air in units of gray per hour (Gy/h) The spec for CRT monitors is <5000 nG/h (<5µG/h) but MPR & TCO testing has yet to find any monitor with measurable X-ray emissions . If you check the spec for any monitor, if they bother to record the test results at all, it will be shown as <100 nG/y which is the normal background level in their testing laboratories . The average television fires electrons at 16-20 keV, medical x-rays use 200 keV and beta radiation from radioactive sources is around 3 MeV . That is 150,000 times greater than the energy level imparted by the electron guns in a TV or monitor CRT . I have run alpha, beta and X-ray checks on my 17" Hyundai monitor and got a zero response . However, sitting in my office I can still record background gamma particle strikes . A couple of millimetres of aluminium will stop 3 MeV of beta radiation, so I think that a steel shadow mask or aperture grill plus leaded-glass faceplate around 1-1 . 5 cm thick will easily contain 20 keV, and so it has been proven . Both television and computer CRT screens have been exhaustively tested and ionising radiation is not on the health-effect horizon because the energy levels are insufficient to damage human tissue or human genetic material . You need have no fears . Cheers Billy 8-{)	Billy T (70)
251629	2004-07-12 06:23:00	just to add to billy..... the only time to worry is when the monitor is faulty eg very very bright. i know of a tech who had radition poisoning from sitting next to a faulty tv all day.	tweak'e (174)
251630	2004-07-12 06:25:00	Awesome info - many thanks Billy T :)	braindead (1685)
251631	2004-07-12 06:52:00	Yeah good work Billy T, but if you don't mind me asking, what do you do all day at work? I mean, to be measuring Gamma particles on your lunch break would be somewhat odd... (no offense to those who do)	Growly (6)
251632	2004-07-12 08:19:00	Re tweak'e's comment, this fault can happen, but is usually accompanied by a very small and very bright image, and a lot of hissing and crackling noises. Most modern monitors have over-voltage monitoring that shuts them down, so it would be very unlikely to happen nowadays. However, back in the 70's a particular premium brand of colour TV used to suffer a tuning capacitor failure that caused this fault. The EHT would rise to around 40-45 kV, the picture would be small and bright, and X-rays would be emitted until the voltage punctured a hole through the neck of the CRT. It was a tribute to the strength of the HV components (capacitor excepted) that the thing could continue to operate in that condition. In the days of valve based EHT generators (USA & UK only, and pre solid-state triplers) the EHT rectifier was enclosed in a metal case to shield users (and techs) from the X-rays. Techie-folklore has it that a few bods who worked for too long or too often with the covers off actually suffered radiation effects. Certainly there was a prominent X-ray warning on the outside of the EHT cage. And how come I can measure gamma rays while eating my lunch Growly? Well firstly I have a range of radiation testing equipment in my kit, and secondly they are the most penetrative of the common radioactivity sources. Apha particles are the skinny weaklings of the class and are easily stopped by a simple sheet of paper. Beta particles are the class bully, but they still get knocked back by a few mm of aluminium or other common metals. Gamma rays though are the Charles Atlas (or Mike Tyson) of the radioactive world and depending on the strength of the source, it can take a truckload of concrete or metres of lead to stop them. Since they are naturally occuring in our environment through radiation bombardment from space, they make it through my puny roofing iron and arrive in my office, making the detector beep at irregular intervals. It will still beep in the basement of an office building, but not so often, which makes for an interesting demonstration of the powers of radioactivity. Sleep easy ]:) Cheers Billy 8-{)	Billy T (70)
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