It is a little loud on high but its super effective. I have 6 kids (4 teenaged boys and 2 toddlers) plus 2 cats so odor control is a constant battle. I bought 2 of these, one for each end of the house. I turned them both on high for an hour and it completely removed stagnant odors! I have one in the room of my allergy ridden son while hes sleeping and even day 1 I have noticed a reduction in mucous while hes sleeping. I wish I would have bought these earlier! They shipped very fast!