UV Protection - Plexiglass - Does it?

[Skull-One]

I was just wondering if the glass used in most jet cockpits (CRJ, ERJ, 717, 777, etc.) protects us from UVA, UVB, and UVC... IOW, if I am sitting in the cockpit in sunlight, am I getting sunburned and not realizing it?

I've already had skin cancer once at a young age, and most sunscreens only shield us from UVA and UVB. UVC is the worst. How much of it are we getting at FL250?

 

[EagleRJ]

The numerous glass, plastic, and metal layers block all UV-A and UV-B rays from entering the cockpit. What's UV-C? Never heard of it.

Cosmic radiation is another thing, though. The higher you go, the stronger the radiation becomes, since density-wise, most of the atmosphere is below you. I've read that on a trip across the pond, you get an equivalent dosage of several chest x-rays. The effect is cumulative and altitude dependant, so one shorter flight at FL510 might get you more rads than a longer one at FL370.

 

[mar]

It's gonna filter some

I'm sure the plexiglass will filter some radiation but I can't tell you how much of what sort.

I once read that one Atlantic crossing was equal to one chest x-ray in terms of radiation.

Obviously that's about eight hours in the mid to high 30's.

 

[Skull-One]

UV-C is the deadliest of the three UV types. It isn't mentioned much because, as I recall, the atmosphere blocks all of it from reaching the surface of the Earth. However, as we go higher we experience an exponential exposure to it with altitutde.... Something like that.

(Edit In: Pilots are potentially more at risk for UV radiation exposure. Since by definition pilots are at higher altitudes, they may be at risk for higher exposure, especially in open cockpits and in hot air balloons. It is estimated that there is a 4% increase in UV radiation with each 1000 feet of elevation.)



"Ultra Violet light has a shorter wavelength than visible light.
The UV spectrum is divided into A, B, C. UV-C is the part from the UV spectrum with the shortest wavelength. Some people are using UV-A light to make the skin brown.

"The more short wavelength UV-B and UV-C light are dangerous for biological materials. All bacteria and virus get a deadly sunburn in a UV-C filter system."

----

"UV-C is "extraterrestrial" solar radiation, and includes light with wavelengths between 100-280 nm. Thankfully for all of us living on earth, UV-C is fully absorbed by stratospheric ozone. In fact, UV-C is a major factor in the continuous creation of ozone in the upper stratosphere. UV-C is also called "hard UV" or "vacuum ultraviolet" in certain disciplines and is useful in many industrial processes and bacteriological applications."

 

[Skull-One]

I just found this on a homebuilder website. I hope he is wrong:


"A common misconception about Plexiglas canopies is that they will adequately protect you from the sun. They don't. Plexiglas will only provide protection in the UVB wavelengths. Thus, while you might not sunburn as badly through Plexiglas, you are still
exposed to UVA. As with sunscreens, since the UVB burning
wavelengths are blocked, one might stay out in the sun longer,
thus being exposed to a great deal of damaging UVA. While the blue tinted canopies look nice and might help you feel cooler, they provide no additional UV filtering."

 

[metrodriver]

true, I flew gliders and you could get a nice sunburn if you didn't watch out. Almost every gliderpilot will wear some sort of floppy hat that shields face, ears and neck.
I've heard from some guys flying long haul in some other countries that scheduling has to use a chart that determines if you had your dose of radiation for the month.

 

[EagleRJ]

Yes, plexiglass or acrylic windows in light planes and sailplanes are transparent to UV rays unless they're treated.

In the case of airliner windscreens, you have not only plastic, but layers of glass as well, and on some aircraft, transparent layers of metal that provide the anti-icing heat. Those will filter all of the UV rays.

 

[carlos]

I'm still in flight training but I'm wearing sunscreen on every flight. My wife, who is a doctor, noticed that I was tanning after just a couple of flights and insists upon it. I don't know if any normal commercial suncreens protect against UVC, though. I can't fly high enough in a C172 where I would really have to worry (I think) about it!!

 

[Skull-One]

Yes, plexiglass or acrylic windows in light planes and sailplanes are transparent to UV rays unless they're treated.

In the case of airliner windscreens, you have not only plastic, but layers of glass as well, and on some aircraft, transparent layers of metal that provide the anti-icing heat. Those will filter all of the UV rays.

Basically. That and we'll all be deaf.

Is the FAA even interested in this subject? We're all getting fried by rads and UV (are the side windows UV proof without the heating elements and such?). We get LG's disease, birth defects in our kids, skin cancer, bad diet, high stress, and early forced retirement...

$300/hour doesn't seem like that much when you factor these things into the equation!

 

[Loafman]

Where the hell are you making $300 an hour? A strip joint?

 

[ReportCanoa]

transparent layers of metal

"Aye laddy, transparent aluminum..."

Someone's been watcing too much Star Trek....

 

[EagleRJ]

"Aye laddy, transparent aluminum..."

Someone's been watcing too much Star Trek....

Actually, that's how it really works, right here in the 21st century.

They heat the windshield in a vacuum and electrostatically apply a layer of either pyrolytic tin oxide or indium tin oxide. It forms a conductive metallic layer that is transparent.

They can't make it thick enough for humpback whales yet, though!

 

[njcapt]

That and we'll all be deaf.

What?

 

[80/20]

It just so happens that Boeing were asked some similar questions recently. Here are some questions asked about the 737 windows in the past and the answers:

Questions

1) Is there any requirement to control the levels of UV exposure inside the cockpit?
2) Have these effects been studied by Boeing?
3) Is there any recommendation to minimize these effects or the UV radiation exposition?
4) Do the windows have any type of UV filter?
5) Is there any regulation change being proposed?

Reply - from Boeing:

1/ There is no requirement to control the levels of exposure inside the cockpit.

2/ These effects have been tested by the window manufactures and other independent studies. However, we are not aware of any Boeing test on UV exposure during typical flight profiles.

NOTE:
Concerns with UV exposure in the cockpit are raised fairly often, usually due to flight crew concern with sun related skin diseases (we believe there is research showing a higher incidence of these diseases with flight crews than with the general population). However as the UV-B transmittance through cockpit windows is less than 1 percent (equivalent to a sunscreen product with an SPF of more than 100), it is not likely that a higher incidence of skin diseases with flight crews is due to exposure to UV light in the cockpit.

3/ There are no recommendation to minimize these effects for the UV radiation exposure.

4/ Light transmission through cockpit windows falls off quickly once past the visible range, and is very low in the more dangerous UV-B range (wave lengths less than 315 nanometers). We estimate that less than 5 percent of the total UV light is transmitted through cockpit windows.

5/ We are not aware of any regulation change being proposed.