> I'm working on an art project that involves illuminating large quartz
> crystals with colored LEDs.  We've discovered that UV LEDs produce a
> most beautiful effect, but we're unsure how to gauge the danger.  The
> LEDs specs say that peak power is at 405nm, (400-410nm range).  After
> quite a long time searching the web, I can't find definitive safety
> info on 405nm light.  Some suggest that it's outside of the dangerous
> UV-A range (though only barely), other sites warn of damage from all
> wavelengths less than 500nm.  Does anyone have any ideas or pointers to
> trusted resources.  Better safe than blind!

Trusted? - no.
But, FWIW Google ( ULTRAVIOLET SAFETY hazard wavelength ) says:
___________________________

VERY USEFUL

Shows wavelength response curve for a commercial UV hazard meter.
The weighting that they place on exposure at a given wavelength gives a good
idea of what you should think (possibly :-) ).

        http://www.solar.com/Applications/app103.pdf

___________________________

 University of Michigan environmental health and safety.

        http://www.ehs.washington.edu/updates/lsu-ja99.htm

UV-A near UV 320-400 low
UV-B mid UV 290-320 mid to high
UV-C far UV 190-290 high

______________________________________

Same people
Slightly different paper

UV-A near UV 320-400 lowest cataracts
UV-B mid UV 290-320 mid to high **skin or eye burns
UV-C far UV 190-290 highest skin or eye burns

*** Notice extra column

http://www.ehs.washington.edu/labsaf/UVlight.htm

______________________________________________

Safety aspects of non lethal tetanisong beam weapon

        http://www.hsvt.org/safety.html


Give some CLAIMED exposure levels.

All ocular damage is a function of both wavelength and intensity. A beam of
shortwave ultraviolet radiation can ionize the oxygen molecules in air
enough to conduct an electrical current (Scheps, 1997) without harming the
cornea (Pitts, 1973). Puliafito et al. (1965) determined that the lowest
per-pulse ultraviolet fluences that will ablate human corneas are 46 mJ cm-2
at 193 nm and 58 mJ cm-2 at 248 nm. Moreover Trokel et al. (1983) found no
evidence of thermal damage during 193 nm corneal ablation even at an energy
level of 1 J cm-2.

BEWARE CLAIMS FROM SUCH SITES

____________________________________________

READ THIS ONE

Not especially quantatative but intertesyting Australian health guideloines

http://www.whs.qld.gov.au/safetylink/health/health07.pdf

_______________________________

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