Bests & Worsts Reviews from Amazon

I bought one of these units for my home office, which is 16' by 10' (160 sq. ft.). My 17 year old cat literally lives inside my office...he is a long-haired cat who sheds constantly. He's also very mean to everyone but me, which upsets me, but that has nothing to do with the review of this air purifier. His litter box is situated in one corner of the room. The smell of the litter box was the primary reason I purchased this air purifier. After using this air cleaner regularly for about two years, I can confidently say that it effectively and completely removes the smell of the litter box, helps control the amount of hair that floats around the room, and generally does a very good job keeping dust from accumulating in the room. On a scale of 1-10...1 being an air purifier that does nothing, and 10 being an air purifier that completely removes all airborne contaminants in the room, I'd rate this unit as a 7. The unit has 3 fan speeds...I keep it on the middle speed. The fastest speed is useless because, while it would obviously clean the room most effectively, it's so loud it sounds like I'm getting an MRI. Even the middle speed is unacceptably loud, but I've gotten used to it. The lowest fan setting is quiet, but it doesn't effectively clean the air in my office unless I'm on the middle fan speed. I always keep the UV light on. I have no idea if that light actually does anything...but since it's there, I might as well use it. I run the fan all the time, 24/7. The filter inside the unit lasts for about 4 or 5 months before I need to replace it. How long the filter lasts for you will obviously depend on several variables, like how dirty the air is in your room, what fan speed you leave the unit on, and how often you run the machine. I would highly recommend this machine to anyone who is looking for a relatively cost-effective and efficient air purifier for a room under 200 square feet. I included a picture of my 17 year old curmudgeonly cat, who is the sole reason I needed to purchase this air purifier. UPDATE (10/10/18): My cat is now 18 and a half years old and still going strong. But, he has become more demanding of me, which has strained our relationship. He often raises his voice at me...he never used to do that. I am concerned he may be losing his hearing, but I can't tell since he's always ignored me most of the time anyway. That aside, the GermGuardian air purifier continues to hum along without a problem. I still run it day and night, 24/7. Other than replacing the filter every few months, the unit has needed no TLC.