The UV Index and why your canopy is your friend

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

Do older canopies also protect against UV, or is it only the newer ones?
Maybe you could do this test on some of older canopies at your
gliderport?


Eric Greenwell wrote:
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.


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.

Some older ones do, some don't. That's what we found by testing a
variety of gliders at our gliderport. So, I wouldn't suggest resting
easy until you've tested your own canopy.

Greg Arnold wrote:
Do older canopies also protect against UV, or is it only the newer ones?
Maybe you could do this test on some of older canopies at your
gliderport?


Eric Greenwell wrote:
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.


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.

wrote:
Greg Arnold wrote:
Do older canopies also protect against UV, or is it only the newer ones?

I haven't tested a variety of canopies, but based on the data sheets
from acrylic manufacturers, and comments by canopy and sailplane
manufacturers, I'd expect even older canopies (mine is 12 years old) to
offer plenty of protection. Acrylic that transmits UVB is more expensive
than the ordinary kind, so there would be little reason to use it.

Maybe you could do this test on some of older canopies at your
gliderport?

Some older ones do, some don't. That's what we found by testing a
variety of gliders at our gliderport.

Do you recall which gliders didn't offer as much protection, and how you
tested the canopies?

So, I wouldn't suggest resting
easy until you've tested your own canopy.

And at $30 or less for a UV Index meter, it'd be a cheap purchase for a
club to make. You only need to check each canopy once! And, if anyone
finds canopies that _don't_ pass the test, please tell us about it.

--
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

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).

Eric Greenwell schrieb:

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.

This is the reason why you needn't care too much about your sunglasses:
In the old days of glass glasses, it was the coating which protected
your eyes. There were good and bad coatings. Nowadays, it's the plastic
itself which protects. Get some cheapo poly-whatever, and your eyes are
protected, even with total clear glasses. Colour filter and sex appeal
may be a different story.

Stefan

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

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

Chip Bearden
ASW 24 "JB"

Eric,

While I agree that a good quality clear canopy (eg
mecaplex) gives a gratifying amount of UV protection
I think that your sources under-estimate the risks
of UVA and the implications of a tan.

As regards tanning, to quote the current opinion of
the British Association of dermatlogists:

'There is no such thing as a safe or healthy tan. A
tan is a sign that already damaged skin is trying to
protect itself from further damage. The protecting
power of a tan is weaker than that of a mild sunscreen
of SPF 2-4.' See:

http://www.bad.org.uk/public/cancer/

UVA doesn't burn the skin as quickly as UVB but it
is much more deeply penetrating and the trend of medical
opinion in recent years has been towards an increasing
appreciation its cancer causing potential. UVA penetrates
cloud cover and light clothing.

I don't know whether UVA tanning beds are used a lot
in the US but in the UK they are very popular and manufacturers
and tanning studios propogate a great deal of misinformation
about 'bad' UVB , 'harmless' UVA and 'safe' tanning.

The message I take from your very helpful finding that
quite a bit of the longer wavelengths of UVA gets through
canopies is the opposite from your conclusion. To
me it emphasises importance of using UVA protective
sunscreens and clothing when flying.

John Galloway

At 23:30 29 September 2006, Eric Greenwell wrote:
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

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