The portion of the UV spectrum that causes burning is 320 nm and
below. Plexiglas filters 98-99% of these frequencies. I have literally
spent hours in my DG at altitudes above 15k w/o any sunburn
whatsoever. I have, however, been severly sunburned on a mountain at a
few hours under 9k. Your greatest UV exposure is the time you spend on
the ramp, before and after you fly. Bewa long sleeve shirts may be
a poor UV filter, so back it up with sunscreen. You can improve your
clothings protection with Sunguard detergent (https://
sunguardsunprotection.com).

Tom

(On Mar 25, 11:14*pm, brianDG303 wrote:
On Mar 25, 9:10*pm, Eric Greenwell wrote:





Bob wrote:
Most sun screen on the market does not filter out all UV, so buyer
beware. * Handily, there are now some clothing products like long
sleeve shirts on the market that are claiming an SPF of 35 that should
help protect much of your upper torso, and gloves and hats, too.

* Consumer Reports and many other reputable sources says it does an
excellent job if it's spf 30 and higher, and properly applied, even it
it doesn't get "all" of it.

You didn't mention what kind of UV meter you used, and "lighting up like
a light bulb" doesn't tell us anything. Was it measuring UVB, or UVA,
both? and what fraction of each? What percentage reduction did the
canopy provide? The type of plastic and it's tinting can make an
important difference: for example, the canopy on my previous glider
blocked all the UVB and over 70% of the UVA as measured with a
spectrophotometer, but not all canopies are not that good.

I have a "sports" UV meter that is calibrated in UV index. It shows
essentially zero UV coming through the canopy on my ASH 26 E. While it's
not a calibrated spectrophotometer, it suggests sitting inside the
cockpit is a lot safer than standing around outside it.

Practically speaking, I think if you are properly protected with
clothing and sunscreen for the rigging and waiting in the towline, you
have more than sufficient protection while flying.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

I use a *Littlemore Scientific UV meter that was developed at Oxford
University to measure UV transmission through different materials and
in spaces where art is displayed and I believe it to be very accurate.
It reads out in mW/M² or µW/lumen and it is mW/M² we are concerned
with here. I once took it out to the airport and expected to see very
little UV transmission through the canopies, based on past experience
with UV through plastic. What I found was that mostly the nicer newer
gliders had canopies that stopped almost all UV, but some of the older
gliders had canopies that let in more than seemed safe, there was an
LS1 with a replacement section that was transparent to UV. The
spectrum of UV you want to block is everything above 420nm or so if
possible.

Tinting can be misleading as I have seen tinted glass before that
reduced visible light without affecting the UV and that is a worst
case situation, as the tinting leads you to think there is protection
when there isn't. However in glider canopies I suspect tinting means a
higher quality product and that would tend to have more UV doping. I
don't think the manufacturers are primarily concerned with human
health as much as the life span of the plastic, the addition of UV
doping agents protects the plastic from the sunlight and blocks UV as
a side benefit. As has been stated the problem is going to be while
rigging and not flying for most of us in newer gliders.

Brian

Brian

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