The UV Index and why your canopy is your friend

These measurements made me curious about what the UVI index is, so I did
some searching and learned a few things:

* The UVA band (315 nm to 400 nm) is the primary tanning and
wrinkling band

It is also the primary basal and squamous cell skin cancer band.

The UV coming through you canopy can kill you. Protect yourself from it
properly.

wrote:
Are most glider canopies made of approximately the same thickness
material?

All the ones I've looked seem to be about 0.60". Typical acrylic's
cutoff is steep and deep (1% transmission below the cutoff), so even
twice the thickness makes little difference. The acrylics designed to
pass UV (at least from the Cyro company) have a more gradual "tail".

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Guy Byars wrote:
I must strongly disagree with Eric's post!!!

He talks about wrinkling and skin damage (sunburn?). Well, if you are only
concerned about sunburn and wrinkling, then go ahead and depend on the
canopy for your protection.

However, nowhere in Eric's post does he mention SKIN CANCER!

The UVA range of the sun's spectrum has a longer wavelength and penetrates
right through your canopy and deeply into your skin. There is a large body
of research which ties UVA exposure to skin cancer.

http://healthlink.mcw.edu/article/964647970.html

The canopy does provide some protection, but it is not sufficient. The best
protection is to cover yourself with light colored clothing and a good
protective hat while flying. Certainly a broad spectrum sunscreen should be
used as well.

I certainly agree with these cautions, and they are needed even more
outside the cockpit, where glider pilots also spend a lot of time.

I read the article, but now I'm confused that the UV Index doesn't seem
to account for UVA, and the article didn't mention it. Can you describe
the reason or point to a resource that does? Perhaps the UV index hasn't
kept up with the science?

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Eric Greenwell wrote:
Guy Byars wrote:
I must strongly disagree with Eric's post!!!

He talks about wrinkling and skin damage (sunburn?). Well, if you are only
concerned about sunburn and wrinkling, then go ahead and depend on the
canopy for your protection.

However, nowhere in Eric's post does he mention SKIN CANCER!

The UVA range of the sun's spectrum has a longer wavelength and penetrates
right through your canopy and deeply into your skin. There is a large body
of research which ties UVA exposure to skin cancer.

http://healthlink.mcw.edu/article/964647970.html

The canopy does provide some protection, but it is not sufficient. The best
protection is to cover yourself with light colored clothing and a good
protective hat while flying. Certainly a broad spectrum sunscreen should be
used as well.

I certainly agree with these cautions, and they are needed even more
outside the cockpit, where glider pilots also spend a lot of time.

I read the article, but now I'm confused that the UV Index doesn't seem
to account for UVA, and the article didn't mention it. Can you describe
the reason or point to a resource that does? Perhaps the UV index hasn't
kept up with the science?

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Hi there,

Eric makes an excellent point...there are some questions that we need
to ask....and he is not the first one to raise up the point. Great job
Eric....

Jacek
Washington State

I think it's the factory canopy but I'm not sure.

Eric Greenwell wrote:
wrote:
Someone brought one of those UV meters out to the field a month or two
ago, probably the same one you have. As best as I recall, it was
reading 12 (extreme) outside. When put under a newish DG800, older
DG200, and very old Kestrel, it read 0. Put under a 20 y.o. LS-6 it
read 3 or 4, indicating only around 75% was being absorbed (still
better than nothing).

Very interesting. It's going to be a while before I'm near a collection
of gliders, so I hope others will buy or borrow a meter and check the
gliders in their club, and report the results.

Do you know if the LS-6 had the original factory canopy or a replacement?

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

So should open cockpit vintage gliders come with a
health warning then?

Del C

At 18:36 30 September 2006, Guy Byars wrote:
I must strongly disagree with Eric's post!!!

He talks about wrinkling and skin damage (sunburn?).
Well, if you are only
concerned about sunburn and wrinkling, then go ahead
and depend on the
canopy for your protection.

However, nowhere in Eric's post does he mention SKIN
CANCER!

The UVA range of the sun's spectrum has a longer wavelength
and penetrates
right through your canopy and deeply into your skin.
There is a large body
of research which ties UVA exposure to skin cancer.

http://healthlink.mcw.edu/article/964647970.html

The canopy does provide some protection, but it is
not sufficient. The best
protection is to cover yourself with light colored
clothing and a good
protective hat while flying. Certainly a broad spectrum
sunscreen should be
used as well.

Guy Byars



'Eric Greenwell' wrote in message
news:x_hTg.79$Oh3.3@trnddc04...
I recently bought an Oregon Scientific UV888 Personal
UV Monitor (~$30).
Among other things, it measures the UV flux and computes
the UV Index
(UVI), then determines a 'safe exposure time' based
on your input of skin
type and the SPF of the sunscreen you are using.

Naturally, I made a measurement in the sun (UVI =
8), then another one
inside the cockpit (UVI = 0), indicating the canopy
provides quite a bit
of protection. Testing other kinds of plastic, like
baggies, plastic wrap,
Lexan, etc., gave readings from 0 to 7, so not every
kind of plastic is
protective.

These measurements made me curious about what the
UVI index is, so I did
some searching and learned a few things:

* The UVA band (315 nm to 400 nm) is the primary
tanning and
wrinkling band
* The UVB band (280 nm to 315 nm) is the primary
skin damage band
* The UVC band is almost entirely blocked by the
atmosphere, so has
essentially no effect
* The UVI is a weighted value that accounts for
the skin's response
to different irradiation frequencies (almost
none to UVA, quite a
bit to UVB)

The most interesting discovery for me is that tanning
can occur without
harmful skin damage (I know, we hate wrinkles, but
they don't kill!), so
getting a tan, such as the tan described by a letter
writer to a recent
Soaring magazine, does not mean you are also damaging
your skin.

Looking at an 'erythemal dose rate' chart, you can
see almost all (99%)
of the dosage in the direct sun occurs below about
330 nm. Since our
canopies block UV below about 360-370 nm, they provide
essentially
complete protection from damaging rays. The fraction
of the UVA that comes
through will still give you some tanning, and some
fabrics will fade
slowly, but your skin is protected from the UVB. This
is very good news,
that the canopy affords even more protection than
I first thought.

So, cover yourself as much as possible (hat, long
sleeves, etc), put the
sunscreen on when you get to the gliderport, do your
rigging and outside
preparation early in the morning, and take shelter
under a wing, under an
umbrella, or inside a building or vehicle (glass protects,
too) while
waiting to take your tow. Breathe easy while you are
flying the glider,
and apply more sunscreen when you land, unless the
sun is low.

This is the main reference I used for my education
and conclusions:

* http://www.aero.jussieu.fr/~sparc/News21/21_Long.html

Other interesting references a

* A simpler version of the main reference (National
Weather Service):
http://tinyurl.com/evfc7

* UV meter:
http://tinyurl.com/f3uuy

--
Eric Greenwell - Washington State, USA
Change 'netto' to 'net' to email me directly

'Transponders in Sailplanes' on the Soaring Safety
Foundation website
www.soaringsafety.org/prevention/articles.html

'A Guide to Self-launching Sailplane Operation' at
www.motorglider.org

So should open cockpit vintage gliders come with a
health warning then?

No, the gliders with canopies should have the following warning:

WARNING: Do not depend on this canopy for protection against the sun. Even
though you might not receive a sunburn through this canopy, you will still
be exposed to the sun's UVA wavelengths. The UVA wavelengths are a proven
carcinogen. While using this canopy you should still protect yourself with
opaque clothing and broad spectrum sunscreens.

Derek Copeland wrote:
So should open cockpit vintage gliders come with a
health warning then?

Del C

Yep. Just like a cigaret pack.
"Use of this product may be injurious o your health"
Or maybe.
"The state of California has determined it may cause cancer"
:-)
...lew...

Guy Byars wrote:
So should open cockpit vintage gliders come with a
health warning then?

No, the gliders with canopies should have the following warning:

WARNING: Do not depend on this canopy for protection against the sun. Even
though you might not receive a sunburn through this canopy, you will still
be exposed to the sun's UVA wavelengths. The UVA wavelengths are a proven
carcinogen. While using this canopy you should still protect yourself with
opaque clothing and broad spectrum sunscreens.

Guy, I seem to recall an article from a long time ago where you wrote
about adding tinted film to the canopy. Are you aware of what it takes
to have a canopy that blocks, say, at least 95% of the UVA? I've been
unable to find charts showing the transmission figures for tinted
acrylic. I suppose there might be coatings that could be applied by
either the material, canopy, or sailplane manufacturer, but I don't know
if these are available, practical, or even useful.

I use two plastic sheets on the inside of the canopy during the winter
to prevent fogging/frosting of almost the entire canopy during wave
flying . If these were made of a UVA blocker plastic or had the
appropriate coating, they could be left on all year. Even better would
be a anti-UVA coating with anti-scratch properties than could be applied
to a finished canopy.

The pilot would still need to protect himself while outside the glider,
but a completely protective canopy would eliminate many hours of
exposure. Sunscreen could be wiped off the face just before getting into
the glider, preventing the eye irritation/blinding problem.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

You might include additional warnings, since we're WARNING and PLACARD
happy he

"To avoid injury to eyes, soar with eyes closed."

This has been shown effective in reducing the fear factor, too.

FWIW, I plan to keep using my Ray Ban G-15 lenses, heavy as they are,
and the "Water Babies" (easier on the eyes) SPF 30, 40 or 50 (when I
can find it), the ubiquitous soaring cap (which some folks feel are
more effective than BCG's worn by us engineers), and of course, lip
balm.

Those that know me will attest to the fact that I come in two colors:
1.) pale and 2.) extra-crispy.

Thanks, Eric...until now I hadn't thought to try and quantify wether
the canopy acted as a filter or a magnifying glass...of course, the
sports canopy on my 1-26 adds another factor: windburn!

Cheers,

-Pete
#309