That's not necessarily true. I wish we could control where people display prints but we can't. Unfortunately "collectors", aka, the wealthy people who buy expensive photography, more often than not, in my experience, put them on the wall right beside a big window or under a skylight. They usually have a house full of color work hanging in fairly bright light, and certainly enough to burn out these brightening agents in short order. The issue, as Mark has pointed out a million times, is the it is very common to have much, much greater intensity than 450 lux for short periods of time than it is ever as moderate dosages. Short bursts of real intensity can really quickly damage them, like from here in Atlanta, or California, Florida, Arizona, New Mexico, Colorado, Nevada, etc, etc. I've seen it happen, and I've seen the C prints and Iris prints go green or red right there in their homes. It isn't a theoretical issue for me, I've seen it first hand. And I've seen friends Epson Ultrachrome prints turn gray in the whites on the old "archival matte" garbage right in the middle of a show in a public space under sky lights, in a couple of weeks. And these were for sale. I also recommend uv glass for any client that is going to have anything in bright light for any period of time. That is the easiest way to cover you self.
quote author=ErikKaffehr link=topic=60227.msg486025#msg486025 date=1323897961]
I see that some art is sold as decoration. That kind of art would hang on display, possibly in intense lighting, but not for very long times (like > 50 years).
Art that is sold to collectors would probably stored in dark conditions, hardly continuos 400 Lux lighting assumed in the aging tests. So I guess that the humble permanence figures for the Epsons actually quite OK.