Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: How long do you keep the unit on and which setting?
Document: The fan is a little loud on the high setting but otherwise a very good product. Definitely true HEPA protection.
helps keep the clean air flowing for peolple with breatthing issues. would recommend to anyone that needs something like this
It doesn't,t do a thing. My prefilter again was fully covered in white grey dust but nada from the clever sensor...It,s best to just visually check the back of the unit once a month to see the dust build up on your prefilter.
I had the unit for three months and so far it works.ProsUnlike my other older Honeywell, it,s packaged styro free...thank you Honeywell.It, s no frill basic model at half the cost of the larger and more complex electronic model.
Not anymore. Just make sure you don,t smell the flowers and please keep all the windows closed!I can now smell better and don,t wake up with dry mouth because my nasals were clogged and swollen.I have less problem sleeping now.ConsIt,s by no mean quite...
bought this for my stepson's room. he suffers terribly from allergies. he keeps his door shut at night and we positioned this right next to the floor register. so when the AC is on it pulls in the cool air coming in and gets filtered again before it goes out into the room. he wakes up much less stuffy and seems to sleep a bit better either due to the white noise of the fan and/or the much cleaner environment.
This is a good little cheap air filter
So far the filter works wonderfully. It's a bit loud when turned all the way up but not bothersome. No allergy symptoms so far this season, so I take it as a good sign! :)  Will be sure to update if there are any changes.
I work in a machine shop in the office. the smells of machine oil, mineral spirits, and rust inhibitor run rampant just outside my door. Now that I have this, the smells STAY outside my door.
I was hoping that it would also work as a fan and blow some air to help cool the room but its not a fan so no biggie, out side of 4 feet the air disperses so you really dont feel a breeze. seems to work great. we will see how dirty the filters are when it comes time to change them.
Answer: Lately, I put it on the high setting when I am not home, and change it to low when I am home so it is quieter.  I have not had it very long, so this may change.