Todays PPOT mind bender, is it safe to look into a black light?

[scottmandue]

Okay all you brainy engineers and PhD types.

A friend of a friend is building an art work with exposed florescent black light tubes and being that we work at a science museum of course she asked us if it is safe to look at directly.
On one hand it is just a fluorescent light but on the other hand it is dark so your eyes don't dilate as if you were looking into a regular light of the same intensity.

What think ye?

[stomachmonkey]

Scott,

How old are you?

Some of us were of an age during a time when direct exposure to black lights, strobes, and recreational substances were a normal part of our day.

For a while there black light was the only light in my room.

Other than short term memory loss I think I'm largely unaffected.

[sammyg2]

Here's a clip from wiki on the subject. It does not directly address the effect on eyes but in most cases if it affects the skin it wil laffect the eyes at least as much or more:

Ultraviolet (UV) irradiation present in sunlight is an environmental human carcinogen. The toxic effects of UV from natural sunlight and therapeutic artificial lamps are a major concern for human health. The major acute effects of UV irradiation on normal human skin comprise sunburn inflammation (erythema), tanning, and local or systemic immunosuppression. ”

UVA, UVB and UVC can all damage collagen fibers and thereby accelerate aging of the skin. In general, UVA is the least harmful, but can contribute to the aging of skin, DNA damage and possibly skin cancer. It penetrates deeply and does not cause sunburn. Because it does not cause reddening of the skin (erythema) it cannot be measured in the SPF testing. There is no good clinical measurement of the blocking of UVA radiation, but it is important that sunscreen block both UVA and UVB.

UVA light is also known as "black light" and, because of its longer wavelength, can penetrate many windows. It also penetrates deeper into the skin than UVB light and is thought to be a prime cause of wrinkles.

The reddening of the skin due to the action of sunlight depends both on the amount of sunlight as well as the sensitivity of the skin ("erythemal action spectrum") over the UV spectrum.UVB light can cause skin cancer. The radiation excites DNA molecules in skin cells, causing covalent bonds to form between adjacent thymine bases, producing thymidine dimers. Thymidine dimers do not base pair normally, which can cause distortion of the DNA helix, stalled replication, gaps, and misincorporation. These can lead to mutations, which can result in cancerous growths. The mutagenicity of UV radiation can be easily observed in bacteria cultures. This cancer connection is one reason for concern about ozone depletion and the ozone hole.

As a defense against UV radiation, the body tans when exposed to moderate (depending on skin type) levels of radiation by releasing the brown pigment melanin. This helps to block UV penetration and prevent damage to the vulnerable skin tissues deeper down. Suntan lotion, often referred to as "sun block" or "sunscreen", partly blocks UV and is widely available. Most of these products contain an SPF rating that describes the amount of protection given. This protection, however, applies only to UVB rays responsible for sunburn and not to UVA rays that penetrate more deeply into the skin and may also be responsible for causing cancer and wrinkles. Some sunscreen lotion now includes compounds such as titanium dioxide which helps protect against UVA rays. Other UVA blocking compounds found in sunscreen include zinc oxide and avobenzone. There are also naturally occurring compounds found in rainforest plants that have been known to protect the skin from UV radiation damage, such as the fern Phlebodium aureum.

[daepp]

Mr brother ended up in an emergency room with burned eyes caused by painting a veterinarian's office 2 days straight. It seems there were many black lights used for germ elimination and they burned his eyes.

[surflvr911sc]

There is a big difference between a UV light (for sterilization) and a 'black' light (EDIT: even though they look the same). The only issue w/ a black light would be how much UV radiation a specific bulb emits, which can be filtered very easily.

[vash]

let me ask my magic 8 ball.............

[cashflyer]

It's my understanding that florescent black light bulbs either use tinted glass or a tinted coating on the glass to filter the light. What escapes the filter is the light in the UV spectrum, but at no more intensity than what the bulb would have emitted anyway.

This would differ from a bulb that was specifically designed to emit high levels of UV for the purpose of sterilization or industrial use.

Am I wrong?

[scottmandue]

I am 50 years old so I am familiar with black light posters... I expected UV would be the problem but not sure how much UV comes out of a black light fixture.

Thanks for the replies.

[dhoward]

Originally Posted by cashflyer

It's my understanding that florescent black light bulbs either use tinted glass or a tinted coating on the glass to filter the light. What escapes the filter is the light in the UV spectrum, but at no more intensity than what the bulb would have emitted anyway.

This would differ from a bulb that was specifically designed to emit high levels of UV for the purpose of sterilization or industrial use.

Am I wrong?

ed-zachary...