Steer Clear Of UV Exposure!

It is advisable to avoid exposure, especially visual , to ultraviolet radiation. Accomplish this by steering clear of exposure to UV emitting LEDs, lamps, and excessive amounts of sunlight. While special care is needed when working with lasers, this post does not refer to them. Read the references and take the advice...or leave it! They are, after all, YOUR EYES . In the case of sunlight, protect the skin with high SPF lotion and protect the eyes with properly rated UV blocking sunglasses . UV LED flashlights and all UV energy sources are potentially hazardous. Radiant energy in this band has a well-established causal relationship to cataracts . Observable adverse effects generally result from chronic exposure; however, UV damage to the eyes is cumulative and irreversible . If you must work with UV sources, use approved UV protective eyewear.

http://www.webpost.net/ne/netab/uvleyes.htm
http://www.arn.org/currpage/uvhealth.htm
http://www.aad.org/pamphlets/UVIndex.html
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3185661&dopt=Abstract
http://ohioline.osu.edu/cd-fact/0199.html
http://www.framesdirect.com/lens_options_ultraviolet.asp
http://www.shadeseyewear.com/damage.htm
http://members.misty.com/don/uvbulb.html

Be safe, not sorry!

L3

I don't think too many of the folks playing with UV LEDs look directly into them, but then again, there was that guy with the HeNe laser that looked directly into the beam...

Say, could you edit your links to eliminate the side-scrolling?

Here's the easy way to do it:

<font class="small">Code:</font><hr /><pre>
link
</pre><hr />

Dr Yatsu

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idleprocess said:there was that guy with the HeNe laser that looked directly into the beam...

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A laser and a 'usual' UV source are two very different things.
IMHO these UV hysteric reactions are highly overrated (as laser safety is underrated sometimes).

All these UV sources produce an energy density several decades lower than sheer sunlight (who has the numbers? I'm shure it is more than 1:1000).

Especially the warning 'be aware of UV incandescents' could be out of a comedy: A UV incandescent is nothing else than a normal incandescent whith a blocking layer which blocks the visible light. Not anything more.
Of course the eye's pupil is more open in the dark, but this is much less of a difference than real sunlight.
Especially UV LEDs have pretty longwave UV, the 'softest' kind. Even when looking directlyinto the beam, your retina gets onyl a small fracture of what it gets outside.

Mankind spent most of it's time outdoors under direct sunlight. That does not mean that you should go unprotected into the sunlight when you are not used to it.

Most of the warnings (if not all) are probably for legal reasons. Even when UV would be complete harmless, they would write it,a s they just do not want to deal with people claiming some damage.

Just my 2 cents worth...

Of course I know that professional fear makers will jump in now and tell me names .-)

When we have 250nm LEDs available which put out several W of optical power, I will change my posting.....

And actually you can damage yourself with almost anything, with something it is just easier.

PeLu:
I was obliquely suggesting that the original post was an over-reaction to the hazards of UV light sources - especially miniscule ones such as UV LEDs.

remember playing with a single 5mm
400nm uv led at max power connected
to a power supply in the dark.
Checking out what would glow and stuff.
I played with it long enough that my
eyes felt gritty
about an hour later.
The grittyness went away.
then I read the warning on the
led museum site

kinda scary

I am more careful now
I only have 1 set of eyes

I guess my post is not
causing the need to scroll
back and fourth

Idleprocess - I believe it is that line of code that causes the most scrolling; then L3's links.

Using light sources in the dark is the most dangerious time, since your pupils will be the open the most

Thats the problem with some light sources, most people assume that its only dangerous if they can see it

Mike,

You make an excellent point. An example of extreme risk is represented by direct viewing of a total solar eclipse. The pupils will be wide open. IR radiant intensity remains very high, even though the solar disk will appear dark. What you don't see can be very injurious.

UV can be very harmful to the skin as well. The incidence of skin cancer has been rising dramatically over the past 2 decades. Use sun protection when outside between 11am and 4pm during the summer.

NUV and UV LEDs you can get today emit longwave UVA, which is not very harmful to skin.
It's the shorter wavelength and more energetic UVB and UVC radiation that you need to be careful with.
These wavelengths can cause skin cancer and sunburn.

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markdi said:
remember playing with a single 5mm 400nm uv led...
my eyes felt gritty about an hour later.

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All the warnings I know only regard to long time damage, your sensation could easily be anything else (or you have experienced something new).
And again, if your eyes are affected by long wave UV that much, how would it be outdoors?

As I wrote above, the difference in between a strong UV lamp and the sunlight is more than 1:1000 !
And the difference in between a small and a completely open pupil only about 1:5 in size, that means in between 1:20 and 1:30. That means that your eye gets still more than 30 times the UV in sunlight with small pupils than when playing with a strong UV lamp (anybody who has better numbers, please correct me, I'm writing out of my memory). And I think it is even more difference for the UV part. Additional you spent (usually) much more time in the sunlight than playing with UV lights.

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An example of extreme risk is represented by direct viewing of a total solar eclipse. The pupils will be wide open.

[/ QUOTE ]Has nothing to do with UV, but even at the darkest moment of a solistice is still brighter than indoors (except for you guys with several kW of CFL at home .-)

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I only have 1 set of eyes

[/ QUOTE ]I do not even have that.

I'm still believing that all the other dangers involved are much higher.

And even outdoors: UV is the vitamin of the sunlight and necessary for health. As always an overdose is bad.
Your affection by UV is also influenced by other things, like medication and your diet.

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The incidence of skin cancer has been rising dramatically over the past 2 decades

[/ QUOTE ]People living at the highest regions in Asia are exposed to (for us) incredibly high doses of UV and do not have much lower cancer rates as we have. So there must be more than just the UV (although it does its share)

Also the warning not to look into an UV LED is useless: People who would do so you will also have to tell not to punch out their eye when they get a knife...


The chief danger in life is that you may take too many precautions
Alfred Adler (1870-1937): Austrian psychiatrist

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PeLu said:
[ QUOTE ]
The incidence of skin cancer has been rising dramatically over the past 2 decades

[/ QUOTE ]People living at the highest regions in Asia are exposed to (for us) incredibly high doses of UV and do not have much lower cancer rates as we have. So there must be more than just the UV (although it does its share)


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I am not sure exactly what you mean here, but yes, clearly genetic or racial factors such as skin color (just to name one) have a huge bearing on the relative risk of skin cancer. Unfortunately we cannot control our genetics as easily as we can control our UV exposure. It is considered to be a medical fact that UV exposure is a cause of skin cancer and is most dangerous to those most vulnerable to its harmful effects. But excessive UV poses some level of risk to everyone. There is reliable epidemiological evidence, supported by laboratory studies that indicate this.

And as for your warning about taking too many precautions: that is interesting and very true in a philosophical sense, but not taking enough precautions can also pose a real risk to your health and safety. As an example, consider the person who crossed the street without looking and got hit by a bus. He should have taken more precautions.

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L3 said:
Mike,

You make an excellent point. An example of extreme risk is represented by direct viewing of a total solar eclipse. The pupils will be wide open. IR radiant intensity remains very high, even though the solar disk will appear dark. What you don't see can be very injurious.

[/ QUOTE ]

Being an amature astronomer, I have to point out that there is NO danger in watching a TOTAL solar eclipse, DURING totality. Before and after are a totally different matter.

A foolish statement, to say the least. /ubbthreads/images/graemlins/whoopin.gif

Totality varies from one eclipse to the next, depending mostly on how far the earth is from the sun during the event. If the earth is closer to the sun (during summer in the northern hemisphere), there can be significant coronal exposure to the naked eye during the "totality", because the moon can't fully cover the "larger" (read: closer) sun.

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wholeflaffer said:
Totality varies from one eclipse to the next, depending mostly on how far the earth is from the sun during the event. If the earth is closer to the sun (during summer in the northern hemisphere), there can be significant coronal exposure to the naked eye during the "totality", because the moon can't fully cover the "larger" (read: closer) sun.

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I do believe that the variation in the size of the moon is greater than that of the sun, and is the primary reason for such "annular" eclipses, where the moon is ringed by the slightly larger sun.

As those are, by definition, not total eclipses, the concept "totality" does not apply to annular eclipses... only to those with complete, or total, coverage.

I also suspect that the danger of anular and near-total eclipses is that while the total amount of visible light entering the eye is much lower than normal, it is because the sun is being mostly covered up, not that it has become darker. That means that the total density of energy coming from the exposed solar area REMAINS THE SAME -- and so therefore does the total energy hitting any part of the retina that finds itself bearing the focussed solar image. So people tend not to flinch because the total apparent amount of light is less, but the energy density on the retina remains the same -- resulting in much more time for "burn-in" to occur than would be bearable in full sunlight.

If I'm right about that, it means that looking at the midday sun when it is almost but not quite obstructed by a faraway edge, like a tall building, might carry the same risks.

I agree with pelu. When I go about living my life, I always think about how humans lived in the past and what are biologically adapted for to decide what I should and shouldn't do. This is one of the reasons I avoid hydrogenated oil and nutrasweet, and also one of the reasons I don't worry about getting a little sun, don't wear sunglasses, but do know my limits when it comes to sun exposure.

The people who get skin cancer are the ones that way overdo it and do it for vanity.. laying out in the sun that is. They will often fall asleep and end up getting burnt, and sunburns, where the skin turns red, mostly a result of the UVB rays, is where most of the the damage is done.

Me, I do like to be outside, but I don't lay around and tan for the sake of tanning, (yard work, running, etc) although I'll build up a natural tan because I don't use sunscreen, and once I have that, it's very rare that I ever get burnt while outside. I think people take this whole UV risk way too overboard as much as the people who sit out and tan 6 hours a day then go to tanning salons in the winter take it way too overboard. Everything in moderation is a good rule to go by. The best thing to do if you enjoy being outside, say an hour perhaps 2 a day on average all the time is to build up a base tan in the spring from whatever you are doing outside, and keep it all summer. Otherwise you'll be pasty white and the days you do go out and forget to put on sunscreen you'll burn to a crisp, doing more damage in one small time period then from weeks of being outside with a natural resistance to the sun built up already.

For longer periods of time.. say 3 or more hours a day, even with a base tan, you'll do your body good in the long run with a some sun protection... our ozone layer isn't quite what it used to be after all.. especially in nations like Australia.

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stockwiz said:
I agree with pelu. When I go about living my life, I always think about how humans lived in the past and what are biologically adapted for to decide what I should and shouldn't do.

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The human races didn't evolve under a depleted ozone layer and they also basically didn't travel far from their homeland regions to lower latitudes during the evolutionary stage (for example, caucasians living in the United States or Australia). Modern humans have to deal with those factors as well as other environmental stressors such as a greater level of pollution in our environment and toxic chemicals in our food supply. We also have a longer potential life expectancy than ever before in history. These factors increase the liklihood of contracting skin cancer during a lifetime and indicate that we should be more cautious with UV than ever before.

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The people who get skin cancer are the ones that way overdo it and do it for vanity.. laying out in the sun that is.

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That will increase your risk, but my father never sought a tan in his life, but died of skin cancer anyway.

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I'll build up a natural tan because I don't use sunscreen, and once I have that, it's very rare that I ever get burnt while outside. I think people take this whole UV risk way too overboard

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Developing a base tan is a degree of protection from burning, but the tan itsself is an indication that damage has been done to the skin (damage is incremental and cumulative over a lifetime). This goes against conventional wisdom, but is the current prevailing medical opinion. There is no healthy tan except one that is painted on.

Have fun, but please take sensible precautions. Cancer is a drag.

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wholeflaffer said:
A foolish statement, to say the least. /ubbthreads/images/graemlins/whoopin.gif

Totality varies from one eclipse to the next, depending mostly on how far the earth is from the sun during the event. If the earth is closer to the sun (during summer in the northern hemisphere), there can be significant coronal exposure to the naked eye during the "totality", because the moon can't fully cover the "larger" (read: closer) sun.

[/ QUOTE ]

That is not a 'Total Eclipse' , that is an 'Annular Eclipse'...
BIG difference, and they do not look ANYTHING like each other.

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Canuke said:
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wholeflaffer said:
<snip>
I also suspect that the danger of anular and near-total eclipses is that while the total amount of visible light entering the eye is much lower than normal, it is because the sun is being mostly covered up, not that it has become darker. That means that the total density of energy coming from the exposed solar area REMAINS THE SAME -- and so therefore does the total energy hitting any part of the retina that finds itself bearing the focussed solar image. So people tend not to flinch because the total apparent amount of light is less, but the energy density on the retina remains the same -- resulting in much more time for "burn-in" to occur than would be bearable in full sunlight.

If I'm right about that, it means that looking at the midday sun when it is almost but not quite obstructed by a faraway edge, like a tall building, might carry the same risks.

[/ QUOTE ]
Exactally... I think that is where the danger of looking at someone arc-welding in the distance comes from...It does not SEEM bright, but the point source is VERY bright.
Of course distance DOES matter, otherwise you would leave burnt lines all over your retina every time you looked at the stars at night /ubbthreads/images/graemlins/eek.gif