Here’s your chance to sound off about this week’s column:
http://www.straightdope.com/columns/990910.html
I’m an allergy sufferer and have heard similar claims for various air filters, ionizers, etc. I’m also an electrical engineer and can share with you my views on these devices below. My thoughts are, go ahead and try some of these devices (I currently am trying some myself) BUT follow these three suggestions, 1) Make sure you get some type of money back guarantee or 30 day return policy. 2) If the device produces ions or ozone, be sure the device produces .05 to .10 PPM or less. 3) I prefer to try only units that are UL/
CSA approved or some other type of agency or testing body such as AHAM, etc. If you read some of the below links, you’ll see these .05 - .10 PPM figures are the current EPA/OSHA standards for exposure to these items.
I will attach some very interesting links to other sites that can shed some more information (or confusion) on the basic subject of IAQ (Indoor Air Quality). NO, I have no personal interest in any of these sites, I’m just sharing what I have found so far. THERE IS A LOT OF DEBATE GOING ON ABOUT THESE DEVICES! My personal feeling on this subject is if it helps with my symptoms and causes me or the environment no harm, I’m going to try it. As Unca’ Cecil points out, this is a new industry like X-ray technology was at the beginning of this century. Most everyone agrees that we have increasing air pollution/quality problems both indoors and out. It will be many years before we fully understand how all of the items we have floating in our air will affect us long term.
Related Links-
http://www.escape.ca/~nancyt/
http://www.nea.org/hin/air/board/messages/142.html
http://www.hc-sc.gc.ca/main/drugs/zfiles/english/publicat/acozone.html
http://home.inreach.com/bhard/
http://www.epa.gov/iaq/pubs/insidest.html#Improve5
http://www.epa.gov/iaq/pubs/hpguide.html
http://www.epa.gov/iaq/pubs/residair.html
http://www.sharperimage.com/ProductDisplay.jsp?name=SI624
http://www.consumersdigest.com/cgi-bin/WebObjects/CD.woa/wo/3.16.0.1
http://www.alpineindustries.com/
The only thing I can imagine they do (and of course I haven’t done a real study) is to ionize particles in the air–that is, give them a static charge–so when they get near objects with relatively opposite charge, they stick. Of course, this only works in dry environments.
Just to open up another question–is it the ozone you smell when you sniff one of these things? Kind of a pungent onion-like smell (at least it is to me). It doesn’t smell like anything else in the world, so it must be mystical, right? 
Hey, aren’t you supposed to be at work?
The US Navy has been using electrostatic filters or ionizing filters or whatever you want to call them (I prefer super whamadyne ozone smelling, bitch to clean, knock you on your ass when you try, electrical filters) for years. Maybe that would be a good place to get some empirical evidence.
“If you stick your finger in a pie, whatever is in the pie will be on your finger, and whatever is on your finger will be in the pie…unless you wear a rubber glove”----some demented old lady
I believe Cecil stopped too soon in his translation of HEPA filter. You have to keep “HEPA” and “filter” together for it to make sense. It’s not “high efficiency particulate air” - it’s “high efficiency particulate air filter”. It is an air filter that removes particulate (very small things) at a highly efficient manner (it gets most of the particulate).
FWIW, I always heard HEPA stood for High Efficiency Particulate Arrestor.
Now if someone can tell me what UPLA stands for…
To my understanding “HEPA” had always been the acronym for “High-Efficiency Particulate Attenuation” and were first designed to attenuate radioactive particles from air exhausted from nuclear research and energy facilities. Over time, this has been bastardized to “High-Efficiency Particulate Air” because clever marketer wanted to sell this technology to allergy sufferers and figured most people would’t know what attenuation meant, but everybody knows what air is.
I also believe there is some confusion because HEPA is also used in the nuclear industry to denote “High-Efficiency Particle Absorber” (i.e atomic shielding).
I agree that the methodology of the study
you cited is suspect, and I realize that your intent was (presumably) not to debunk bright-light therapy, but I do wish to respond to your apparently cynical view of this therapy. A number of (well-conducted) studies have found that bright-light therapy can alter circadian rhythms, and is effective in treating some types of depression, including SAD (Seasonal Affective Disorder).
SAD sufferers experience depressive symptoms
in the winter months when they have less
exposure to sunlight. This is a physical (biochemical) response. Sunlight is used by
our bodies to produce vitamin D and various
other chemicals (as evidenced by the tanning
process). Bright-light therapy makes use of bright, broad spectrum light to mimic natural sunlight, allowing the necessary
chemical reactions to take place, and thereby alleviating some of the symptoms.
sheilaf
How about a link or reference to said studies? I always get skeptical of such claims, but I also don’t follow the area, and concede they may exist. 
HEPA stands for “high-efficiency particulate air.” The origin of the term is probably from the US Dept of Labor, Mine Safety & Health Admin. (http:\www.msha.gov) HEPA filters have been used in respirators for decades but are probably most associated with asbestos protection.
You might want to also take a look at
http:\www.purestairandwater.com
it provides lots of good information in simple terms related to indoor air purification and the various units available.