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