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UltravioletPhotography

How much UV is Bad for me


Damon

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So I have a few basic questions:

 

My Blak-Rays say 21,700 µW/cm2 at 2 inches from the object or 8,900 µW/cm2 at 10 inches to target.

-- How does this translate into language I can get meaning out of?

-- If I put my hand 2" away from this light, how long would it take to become something I should be really concerned with? (I don't plan on doing that BTW).

-- If I spend 2 hours in my shed taking pictures and am wearing a UV mask (scuba looking goggles) is the rest of my exposed skin in trouble just from the ambient UV?

 

I realize that I could just get a UV helmet, gloves, etc. and cover myself completely--and I may do that but I just want to know what all this means.

 

Thanks so much!

 

-Damon

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Damon, I am sorry that we do not have answers for these specific questions.

Although some readers may have links to offer for UV exposure guidelines. (Please post them, thanks!)

 

For starters in your research, check what the Blak-Ray company has to say about this.

Of particular concern are the following:

  • What is the spectrum of your particular Blak-Ray model?
  • How much UV-B and UV-C does it emit?
    The UV-C range is very, very dangerous. I hope there is no UV-C. The UV-B range is used medically, so you may be able to find some exposure guidelines on medical websites for UV-B. It is UV-B which causes tanning.

Once you know what the Blak-Ray is emitting, you can better select protective gear.

 

Regardless of its spectrum, were *I* to use the Blak-Ray for two hours I would have long sleeves, welder's mask and probably light gloves (with fingertips cut out).

 

Check such sites as OSHA, welder's unions, UV medical usage and so forth for their UV exposure guidelines.

 

For non-US readers: OSHA = Occupational Safety and Health Administration which is part of the United States Department of Labor, a federal government cabinet. Here are a couple of examples from their site:

 

Protecting Yourself in the Sun (general)

Eye and Face Protection (with more links)

Laser Hazards - from which we have this chart

 

TABLE III:6-3. SUMMARY OF BASIC BIOLOGICAL EFFECTS OF LIGHT

Photobiological spectral domain - Eye effects - Skin effects

--------------------------------------------------------------------------

Ultraviolet C - Photokeratitis - Erythema (sunburn) & Skin cancer

Ultraviolet B - Photokeratitis - Accelerated skin aging & Increased pigmentation

Ultraviolet A - Photochemical UV cataract - Pigment darkening & Skin burn

Visible - Photochemical & thermal retinal injury - Photosensitive reactions & Skin burn

Infrared A - Cataract, retinal burns - Skin burn

Infrared B - Corneal burn & Aqueous flare & IR cataract - Skin burn

Infrared C - Corneal burn only - Skin burn

 

That's all I have time for right now.

 

PROTECTING THE EYES FROM UV IS THE MOST IMPORTANT THING !!!

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Thanks for the thoughts and research material.

The Blak-Rays are longwave 365 UVA. Didn't see and UVB or UVC in any literature.

I googled some info. but am still not sure what that intensity number means.

 

-D

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Are you sure the measurements are given in microWatts (µW) ? And not milliWatts (mW) ?

 

*****************

Maybe if try to compare the Blak-Ray intensity to sunlight intensity

we can get some idea of how powerful the Blak-Ray is.

 

All radiation from sunlight is equivalent to intensity of 1.36 kiloWatts/m2 at the distance from sun to earth.

That translates to 136000 microWatts/cm2 at the distance from sun to earth

because 1kW = 109µW and 1m2 = 104cm2.

 

(Now what? Whew! Pls wait a minute I have to go look something up.)

 

At ground level sunlight consists of about 3% UV.

So UV-in-sunlight has an approximate intensity of 4080 microWatts/cm2 at distance from sun to earth.

 

The Blak-Ray outputs 21700 microwatts/cm2 at 2 inches or 8190 µW/cm2 at 10 inches.

(Now what? Inverse square law? Pls wait a minute I have to go look something up about the inverse square law.

I can't reconcile 21700 @ 2" and 8190 @ 10". What am I doing wrong? Hmm.....)

 

So let's compare: UV-in-sunlight of 4080 µW/cm2 at sun-earth distance and Blak-ray 8190 µW/cm2 at 10".

 

The Blak-Ray is twice as powerful at 10" as the UV-in-sunlight.

Well, maybe.

 

*****

 

Corrections, please !! >

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Hurray!! Found this: https://www.tedpella...0UV%20Light.pdf

 

I'll copy part of it here. But I have no idea if they are using microWatts or milliWatts because some of the literature seems to use "m" for micro. Which is wrong. TLV = threshold limit value.

 

....the TLV for the spectral region of these lamps is that the total irradiance incident upon the unprotected skin or eyes should not exceed an intensity of 1mW/cm² for periods greater than 17 minutes.

....Blak-Ray® Lamps deliver .... an intensity of 21.7 mW/cm² at 5cm and 8.9 mW/cm² at 25cm distance.

 

Conclusion: You could exceed the recommended dosage by quite a lot in a short time when using the Blak-Ray. Cover up.

 

Remember also that a lot of UV damage is cumulative and does not go away.

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I smell something burning.. :)

Like I have room to talk--my stupid brain can't get close to figuring it out! So I yell at my brain with my brain--smart stuff here.

 

If your last statement is right, we are getting close. So 20 minutes in the sun would be roughly the same as 10 minutes with the Blak-Ray. That's if I am pointing the Blak-Ray right at me I guess.

Thanks for bustin' out your math skills for me.

 

-D

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Wow you found it! What a sleuth! Thanks!

So do you think that means if I am pointing it at my skin? Or ambient as well. Or just cover up you bonehead and stop worrying about it?

 

-D

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Cover up you bonehead cover up....tra la la.... :P :) B) B)

 

Found this: The American Conference of Governmental Industrial Hygienists (ACGIH) publishes the TLVs, that is, the recommended exposure limits. This would include the UV-A (315-400 nm) TLV recommendation mentioned above: No more than 1 mW/cm2 per every 1000 seconds (about 17 minutes).

mW = milliWatt.

(I still don't know of those Blak-Rays are measured in micro- or milli- Watts.)

 

This group - ACGIH - wants to sell you the TLV books, of course. But fortunately the UV TLVs are easily found elsewhere.

 

GOOGLE THIS: TLV ultraviolet

and you can bring up scads of references such as the following -

 

Columbia University, Health Sciences Division: Working Safely with Ultraviolet Radiation

 

****

 

I don't think you can determine how much of your Blak-Ray you are absorbing directly or via reflection without obtaining a meter of some kind and measuring. Remember that you cannot see the UV so you do not really know when your skin or eyes are catching reflections.

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Thanks!

I found that the makers of the Blak-Ray of death also sell a meter just for the B-100 AP's which I have. The manual that comes with it says the meter readout is in radiometric units, ie., microwatts per square centimeter -- µW/cm2.

So now we have to do a conversion? Does that change anything?

I will follow the advice of that Columbia link which is saying basically the same thing as Enrico and others were stating awhile back and you are saying now--just cover up completely with UV protective gear.

 

-D

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Andrea: If the measures indeed were in microwatts the abbreviation would be µW or at worst uW. *Never* m which by definition is 'metre'. Sometimes you can see the unambiguous um (or even worse mµ) instead of µm (micrometre or 1/1000 of a metre), though, if the typesetter lacks the proper Greek symbol.
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Well, to carry on.....

 

The maximum unprotected exposure time at 25cm (about 10") for Damon's Blak-Ray which outputs 8.9mW/cm2

would be, approximately, 1000/8.9 seconds = 112 seconds = 1.8 minutes.

 

This assumes the UVA range for a lamp peaking around 365nm and that stated output is reasonably accurate.

 

And, as before, corrections are welcomed. I'm winging it slightly on the max uprotected exposure time. There may be other factors to take into account.

 

********

 

For UVA the risk in going over the ~2 minute limit is sunburn and dry skin.

 

Guys may think they do not care about "aging" their skin, but perhaps they should?

You will have all kinds of brown spots and wrinkles when you're 75 years old.

 

The other risk in going over the ~2 minute limit is cumulative eye damage leading to cataracts.

So protect the eyes. :) B) B)

 

Have I said that about eye protection at least one thousand times before? Yes! :P B) B)

 

********

 

Always avoid TPR. Bad. That's bad.

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I think that two minutes is too generous. Have you looked at his frightening array of Blakness? It does explain occasional brownouts up and down the Eastern seaboard. I shudder to think of what may be mutating in his shed at this moment. Ah, well, what harm can the swamp thing do in the pine barrens of NJ?
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Thanks for dusting off the dendrites of your math region Andrea. I appreciate it. Doesn't everyone (aside from movie stars) have brown spots and wrinkles when they are 75? B)

That conclusion seems scarier than I thought. Well, if those UV Torches are as powerful as people are claiming then I would be concerned as well. although I doubt people are keeping them on for as long as I am.

 

So do I need eye protection then? B) I will just construct a plexiglas wall with closable holes for arms and a spot to peak at the camera...

 

 

Don't be spreading the Blakness brownouts around or I will have suits arriving at my shed. My neighbor already wonders why their power goes out every other night from 8 to 10.

 

"Brian Bumble here and now some local news--there have been recent sightings of a creature in the Pine Barrens of NJ that scientist say can only be observed when struck with a kind of ultraviolet light". "We go now to a specialist in this area, Reed Curry". "What are we dealing with here Mr. Curry?"

"Well Brian, it apparently fluoresces around 365 nm and is invisible during all other wavelengths of light". "I have been working on a special filter to combat this elusive light cheater called the Optimum Optical Density for Unwanted Wavelengths or OODUV as we call it here in the lab."

 

I can't believe I have been on this forum for this long and the first Jersey joke has just now arrived. You people are too kind. :)

 

-D

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Doesn't everyone (aside from movie stars) have brown spots and wrinkles when they are 75?

NO!! Not if you wear your sunscreen!! Both my Mom and Grandmom never had brown spots. And very few wrinkles when they were older.

 

Me likes the plexiglass wall idea. Or a carbonate suit of armour.

We will keep your secret about the power brownouts !!

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