Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Don't bother

Bought this a year and a half ago to air out a small guest room in our house (we sometimes have a problem with neighbors'secondhand smoke). I used it rarely - less than 10 hours total. The first few times, it seemed to work well and I was happy with it.But when I used it again recently after a long break, I noticed that everything in the room was suddenly covered with a fine grey/black dust! Yuk!I replaced the filters immediately, but then I noticed a strong chemical smell coming from it that gave me headaches and a bad metallic taste in the mouth.Unfortunately it's too late to return this. I hate to throw things like this away, but I wouldn't give this to anyone else, so it is getting tossed.