Air purification systems

I was visited today by a salesman for the Aerus Guardian Air air
purifier, a stand-alone unit that uses a combination of HEPA filter
with activated charcoal, titanium dioxide photocatalysis, and an ion
generator to filter out particulates and destroy bacteria, mold
spores, etc. The FDA has classified it as a Class II medical device.
He would like us to buy these units for our galleries and storage
areas. I was visiting their website, and found some of their claims
a little confusing.  Among these was that the unit's air exchange
rate is "almost 2000 square feet per hour".

My understanding from previous experience with air filtration units
was that air exchange is measured in cubic feet per minute. Am I
wrong here, or merely confused? I am also concerned about ozone. The
website is a little cagey, saying that it does not emit harmful
ozone; is there any other kind? I understand from a little research
that ion generators can emit ozone, but I don't know whether some of
them do and some don't. And then there's the titanium dioxide
photocatalysis, which involves bathing a titanium dioxide coating on
the filter with UV light which reacts with water vapor to form "a
powerful oxidizer" that destroys airborne contaminants. Now I took
high school chemistry more years ago than I will admit, so I'm
probably giving some of you science types material to forward to
your fun-loving friends, but I'd like to know whether these powerful
oxidizers are staying at home in the unit where they belong or
whether they're going out to lunch at the object restaurant.

Seriously, if anyone can speak to the effectiveness, the chemistry,
or the benefits or dangers of these processes, I would be humbly
appreciative. Also, if anyone can speak to his claim that it would
help lower the humidity in these same galleries.

Anne T. Lane
Collections Manager
The Charlotte Museum of History
3500 Shamrock Drive
Charlotte NC 28215
704-568-1774, ext 110


                                  ***
                  Conservation DistList Instance 21:9
                   Distributed: Friday, June 8, 2007
                        Message Id: cdl-21-9-030
                                  ***