As someone who is highly allergic to cigarette smoke and other air pollutants and irritants, I purchased a round Honeywell HEPA air filter when it first came on the market several years ago. It still works well in the living room, but it is quite noisy even on its lowest setting.
This year I purchased another Honeywell air cleaner with a HEPA filter (Model 17400) for my bedroom because I had contacted bacterial pneumonia last year and wanted to make sure I did not get it again. Next, I purchased this Honeywell 17000 Air Cleaner (with HEPA filter) for use in a smaller bedroom which has been turned into a home office and library.
These Honeywell Long Life QuietCare Purifier 17000 really work! This winter I have not had a cold or flu. Also, this Honeywell Air Cleaner with HEPA filter is whisper soft, and I have had no problems with sleeping, working, reading, watching tv, or listening to music when it is running on the low and medium settings. I leave it on all the time, and I've found that it cleans the air best when the door is closed.
It has a convenient handle on the top, so I can move it to another room quite easily. Also, it is light enough that I can take it with me in the car if I want to use it away from home.
The prefilters last about 3-6 months, (and they can be vacuumed often if you have pets who shed). I change my HEPA filter every year, but you can wait 3 years to do so. These filters are easy to change. The Model 17000 is for a smaller room, and the Model 17400 is for a larger space.
Highly recommended for anyone on this Honeywell Air Purifier who has pets, who lives with or entertains people who smoke, and who is allergic to dust, molds, or pollens.