Here are some excerpts from an interesting article by Ctein we found at www.masteringphoto.com
Assuming indoor display at normal light levels, the worst “good” print paper I know of is Epson Velvet Art, a rather primitive material by current conservator standards, Its display life’s 35 years, unprotected. Everything else I’ve looked at checks out at 45–70 years. No prints of value, though, should be displayed without protective glazing. Dust, dirt and other sorts of aerosol and particulate matter in the environment will settle on the surface of the print. Putting prints behind regular framing glass or acrylic increases the range of display lives from 75–120 years, with 85–100 being typical. UV-absorbing glass will improve that by another 60–100%.
Some folks recommend “airtight” framing, to protect prints from gaseous compounds that could attack them. No such thing exists. You cannot make a hermetically sealed frame at any reasonable price. Hazardous gaseous pollutants will diffuse in through any available path at a rate sufficient to attack the print. It doesn’t take a lot, and they’ve got decades. Once you’ve protected the print from aerosols and particulates with simple glazing, you’ve done all you can reasonably do.
Frames that are too “tight” will tend to concentrate any compounds that are generated or outgassed within the frame environment. This is a known hazard for prints. In general, more damage has been done to photographs and art prints over the ages by “protective” materials than anything else, simply because they are in close proximity to the artwork.
The safest course is to use all-metal frames and make sure the the overmatte and backing board are museum-grade, acid-free boards. Use linen tape or adhesive mylar corners to mount the print. As best as we currently understand inkjet prints, if you follow these recommendations inkjet prints are likely to substantially outlast conventional darkroom prints on display.
The annual Curator contest, in search for outstanding and undiscovered fine art photography, has begun. Find your best shots and submit them by the March 26th deadline. 
