I bought one of these in May 2010 from Amazon and its been switched on in my bedroom ever since. I suffer from allergic rhinitis caused by animal dander (we don't have any animals), dust mites, hay fever etc. I have to say that my year round rhinitis symptoms have been much improved since I have been using it.
It's designed to stop the dust mites from breeding so, people who expect it to work after a week, it won't, you need to do some intense vacuuming and cleaning first, then it should keep the dustmites under control.
The downside - the unit makes a feint rapid ticking noise, I'm 55 so can barely hear it, but a younger person will probably find it distracting.
Anyway if you're struggling with allergic rhinitis, I would definitely give it a go.
Patrick Worcs, UK
Well it's almost three years on since my last review and I can confirm, it is still working for me, gone are days when my nose would stream every morning and I would need to take anti-histamines to control it. Even last summer my hay-fever was far better than usual. My bedroom is full of stuff and is definitely not dust free, it doesn't control the dust anyway, just the mites. It's been in place for almost six years now, so I definitely couldn't classify my improvement as 'psychosomatic'.
Reading other reviews, the results have been mixed, everyone is not the same, everyone reacts differently to things. Definitely worth a try if you have dust mite allergy...