So about a month ago after much research I got an air purifier. I’ve been running it pretty much 24/7 and have seen a big decrease in my allergies! (I’ve also been wearing a mask when cleaning the litter box and handling hay) And sure, sometimes when I’m playing on the floor with Leroy I get a bit sneezy and watery eyed, but overall, this helps a lot and it makes it so much easier for me to sleep at night! Also, it helps cut down on the oder from Leroy’s litter box.
I’m posting this for another member, Battie, who was asking for allergy help. I know an air purifier is a big purchase and I know everyone is tight right now with the economy and job situation being the way they are, but I thought this info might still be helpful for other people. I’m pretty much anal retentive when it comes to doing research before making a big purchase, so in the process of all my reseach, I’ve become fairly knowledgable about air purifiers 
This is the list I considered when looking for an air purifier:
Cost of unit – is it within my budget?
HEPA filters. There are other filters and other filtering technology available, but the HEPA filters catch particles as small as 0.3 microns. “Permanent” HEPA filters – the air purifiers that are advertised as never having to replace the filter – are less expensive in the long run, but they let through more particles and you have to vaccum the filter monthly to keep it clean enough to be effective.
Cost of replacement filters and life of filters.
Activated charcol filters – these reduce oder. Not every air purifier has the option to put in charcol filters with the regular filter.
Size of unit – is it big enough and does it filter the air quickly enough for the room I will be using it in?
Noise level – are you going to be using it in a bedroom where the noise might bother you?
Ozone – does the air purifier produce ozone? Is this something you are concerned about (I am – why bring in more harmful stuff?!)
Styling – how would the air pufrifier look in your house? Do you want a tabletop one, or a larger one for a whole room, or one that is wall mountable? Do the looks even matter to you?
Display on the unit and usage options – Does it have a “replace filter” light? What about different fan speeds? A remote? Are the lights on the display panel too bright for a bedroom?
Energy usage.
UV-C (germ killers)
This was my favorite website when it came to learning about the different types and for getting a fairly objective opinion on different brands of air purifiers. http://www.air-purifier-power.com/
Definitely check out user reviews online of the products you’re interested in, but take all those reviews with a grain of salt. These sites were helpful for reviews but I felt overwhelmed when I went to their websites until I knew what exactly I was looking for. http://www.allergybuyersclub.com/compare-air.html and http://www.consumersearch.com/air-purifiers Consumer Reports did an air purifier review, but I don’t have access to their website so I never saw it.
When looking for air purifiers I found pretty much three different types… the cheap-o ones that are sold in department stores and really do nothing but waste your $, the upper end department store units (better than the cheap ones, but still within my budget) and the hospital grade ones that cost somewhere around $800 and up and are supposedly incredibly good (but WAY too expensive for my need).
There are all kinds of air purifiers that use all different technology – one type may be better for you than another.. so read about them all.
And when you go to make your purchase, check on the return policy in case what you buy really doesn’t work for you.
This is what I ended up with, http://www.lowes.com/pd_302654-8915…er%20lowes and it is incredibly quiet on the low setting. On high it’s a bit noisy, but the fan is POWEFUL so I can tolerate the noise for that kind of power. I generally just run it on low all the time. Unless Leroy just made a stinky.
I keep the air purifier in the living room, but even in in the rest of my apartment I’ve noticed a difference. I can’t tell any more that we have a mystery smoker in the hallway or that I share a ventalition system with the entire building, so it definitely does its job. There’s a remote which is kinda cute, and also an option to turn the lights off on the display. There’s an auto option so it will run on a higher speed if it detects dirty air and also a UV-C light inside the unit that kills germs that you can choose to have on or off. And a filter change light. It takes two HEPA filters and an activated charcol filter (in total, it comes out to $67 every 6 months, but I’ve only had it a month so I’m not sure if I’ll be able to get away with changing the filters less often or not). Like I said I really like the air purifier I ended up with. It had all the things I was looking for and was reasonably priced. It just recently came down $17 in price… it kinda makes me mad when I buy something and THEN it goes on sale.
Hope that helps! Sorry for the long post! I had a lot to say I guess