[Gogglist_pub] my version of aura goggles instructions

[Mark Thorson]

At 10:38 PM 4/5/2010 -0400, you wrote:
>You recommend a maximum exposure of 45 seconds. My recommended maximum is 60
>seconds, so really we are not that far off.
>
>I have done scores of exposures of that timescale using the PranaView UV
>protection with no apparent eyestrain. Is there a compelling reason to
>reduce the maximum from 60 seconds to 45 seconds?

30 seconds is sufficient.  There is no benefit
from more than that.  45 seconds ensures that
the exposure is more than sufficient.  Safety
dictates the minimum effective level is used.

Because old goggles like Kilnascrene were
designed on the assumption that transmission
of UV-A was necessary for their function, they
were dangerous, and even following these rules
strictly will not prevent adverse effects with
those goggles unless UV filters are added.

When the goggles have adequate UV filtering,
there is little or no eye pain caused by the
goggles, but in the absence of well-designed
studies, I think we have to follow a superset
of the safety rules used by all previous workers
in the field.


>A related question: do you think a shorter sensitization is *more effective*
>than a longer exposure?  This is of course something I will try myself
>tomorrow if the day is sunny.  So, a 15 second exposure is actually better,
>or perhaps the exact equivalent of, a 45 second exposure.

No, but a longer exposure is not more effective.

I haven't tried a 15 second exposure.  It may be
equally effective to 30 seconds, in which case
the exposure limit should be lowered even further.
I have no reason to believe that short exposures
are more effective, nor any particular reason to
believe otherwise.