Health Effects Of UV CCFL

[GrahamGarside]

I'd be careful about announcing you have aquired uranium on a public forum, it takes far less to make the axis of evil these days

[Daniel ~]

And even less to fight one! LOL

[aghastpumpkin]

If the UV in cathode ray tubed was harmful, they wouldn't be selling it to you I'm sure.
Photons are not particles in their own right, they are electrons oscillating in the outer shells of atoms. That's what my physics teacher told me. I did my 3 hour Physics AS exam on Friday, it went really well and only on the questions about the Rutherford experiement did a few myth me!

[Gizmo]

CRTs don't radiate any significant amount of UV that I am aware of. They DO have the potential to generate soft X-Rays, though. That's the main reason the front of a CRT is made of leaded glass that is over an inch thick (well, that and to keep stupid people from putting their hands through the front of the tube).

DHHS guidelines require that ALL equipment driving CRTs be designed with intrinsic safety features to ensure that the CRT cannot ever be driven hard enough to generate significant amounts of X-Rays. I used to be responsible for ensuring product compliance with the applicable safety regulations in a former lifetime when I worked for a monitor manufacturer. One of my duties was to take a random sampling of production units for each product family and test them to ensure compliance. We built products for Corner Stone Imaging, Radius, Tek, Rockwell, Sun, and Xerox among others.

Basically, the only way a CRT is going to generate X-Rays is if the anode voltage gets high enough that the electrons from the gun get accelerated to a high enough velocity that they produce X-Rays when they hit the phosphors. So, the simple way to test for this condition is to adjust the unit to produce the maximum possible anode voltage under normal conditions, take your measurements with a radiation meter, and then completely disable the anode voltage regulation circuitry (let the voltage regulator run as high as it possibly can) and measure it again.

Because our monitors were designed for high-performance applications (very high resolution with very good focus), we actually had to get very close to the legal limit for X-Rays, and if the regulator circuit pulled out of regulation, it was possible to exceed the limit. So we had three independent fail-safe circuits that could each shut down the monitor if they detected an overvoltage condition.

Most normal consumer products are designed so that it is not even POSSIBLE for them to produce the voltages necessary to produce X-Rays, so the testing is much simpler (and cheaper).

[Daniel ~]

I'm reassured...a bit":O}

[GrahamGarside]

Basically you want a nice TCO99 aproved monitor, TCO95 shields the screen, but leaves the sides unshielded I believe, so don't go sitting any pregnant friends near them

[Rondog]

I sit in front of an LCD. I dont care.

[GrahamGarside]

LCD's don't give off any emitions to be concerned about, basically just light.

[Gizmo]

Originally Posted by GrahamGarside

Basically you want a nice TCO99 aproved monitor, TCO95 shields the screen, but leaves the sides unshielded I believe, so don't go sitting any pregnant friends near them

Different problem. Monitors have an integrated shield around the picture tube for the purpose of blocking X-Rays, and have had for ages. What TCO95 and TCO99 did was require that the monitors reduce the emission of the magnetic fields generated by the deflection yoke to ensure that it is not of any significant strength outside the monitor chassis. Since magnetic fields are quite pervasive and the currents in the deflection yoke are rather large (as much as 20 amps for the horizontal field), such shielding is both difficult and expensive, especially for the low-frequency vertical deflection field. You would be AMAZED at how difficult it is to block 60 Hz magnetic fields.

[Kaitain]

Originally Posted by Áedán

UVC is the one you really want to avoid, but doesn't make it to the Earth. You're unlikely to have any device that generates much of this. UVB has definately been linked to skin cancer, but there's also a body of evidence that suggests that UVA is not without blame either.

In terms of damage to skin, unless you're noticing you're picking up a tan from your UV, then it's not such a big issue. However, it's not good to look directly at a UV source, as it can cause damage to cornea and the conjunctiva. UVA is known to cause inflamation of these parts of the eye.

UVA is definitely not without blame. This is the band that is used in so-called "safe" sunbeds that is responsible for all those UV-band photographs of pretty young women with ruined faces. All UV causes harm if misused.

It's just due to frequency - UVA is the lowest frequency, so lowest energy. UVB is next up, UVC is "far UV" - at the top end of that band, the distinction between UV and X ray gets lost.

It's down to intensity though. You little cold cathode UV sources should be "soft-UV", which is UVA very close to the visible light band. Some UV sources even glow a pleasing shade of purple. These probably only put out a few hundred milliwatts, which is not enough to cause problems.

About 20 or 25 years ago, certain office workers complained of cataracts, ruined eyesight and a healthy facial tan despite never leaving the office. Monitors have improved somewhat since then...

[Rondog]

Originally Posted by Kaitain

UVA is definitely not without blame. This is the band that is used in so-called "safe" sunbeds that is responsible for all those UV-band photographs of pretty young women with ruined faces. All UV causes harm if misused.

It's just due to frequency - UVA is the lowest frequency, so lowest energy. UVB is next up, UVC is "far UV" - at the top end of that band, the distinction between UV and X ray gets lost.

It's down to intensity though. You little cold cathode UV sources should be "soft-UV", which is UVA very close to the visible light band. Some UV sources even glow a pleasing shade of purple. These probably only put out a few hundred milliwatts, which is not enough to cause problems.

About 20 or 25 years ago, certain office workers complained of cataracts, ruined eyesight and a healthy facial tan despite never leaving the office. Monitors have improved somewhat since then...

My UV cathode's make glow purple.

[Gizmo]

Originally Posted by Kaitain

About 20 or 25 years ago, certain office workers complained of cataracts, ruined eyesight and a healthy facial tan despite never leaving the office. Monitors have improved somewhat since then...

Was this ever substantiated? I never EVER had to test for UV emissions, despite testing to TC095 and TUV requirements (and TUV was hellish; if you could pass TUV, you could pass anything; indeed, most regulatory agencies in other countries would accept the TUV as sufficient proof of meeting their own regulatory requirements).

[cloasters]

My $240 Geiger counter shows no evidence of me being radioactive. I wonder if I need a more expensive one?

[cadaveca]

Originally Posted by cloasters

My $240 Geiger counter shows no evidence of me being radioactive. I wonder if I need a more expensive one?

{insert punch line here}

[Webbyman]

you forgot rocks they are radioactive too :P

[cloasters]

This is unbelieveable as well as tragic. A government paid scientist said that a small amount of ionizing radiation isn't bad for one's health recently. There is no threshold, any and all ionizing radiation harms living things. Yes, some is unavoidable. No, extra radiation does you no good.
Go --sh!

[Rondog]

No radiation is good, but allegedly, the human body can withstand it for a short period of time. Im not sure, im not a biologist.

[Gizmo]

The human body can tolerate a certain amount of ionizing radiation without any appreciable change in condition, because of the healing mechanisms that we have. However, all radiation causes damage and eventually that damage adds up. It is suspected that background radiation is one of the contributing factors to aging, although probably a relatively minor one.

[Rondog]

Originally Posted by gizmo

The human body can tolerate a certain amount of ionizing radiation without any appreciable change in condition, because of the healing mechanisms that we have. However, all radiation causes damage and eventually that damage adds up. It is suspected that background radiation is one of the contributing factors to aging, although probably a relatively minor one.

And why people in remote parts of the world live longer.

[Aedan]

Originally Posted by cloasters

a small amount of ionizing radiation isn't bad for one's health recently. There is no threshold, any and all ionizing radiation harms living things. Yes, some is unavoidable. No, extra radiation does you no good.

Remember that most living things have always had to deal with a small amount of background radiation. As such, they are quite capable of dealing with it. Removal of all background radiation isn't possible, but I suspect if it were, it would lead to odd things happening.