This Holmes air purifier has two cartridges that need to be replaced(I have found) every 4 months. It does above average on our 10 x 20 room. On high power it tends to be a little noisy, but on medium settings is just slight background noise. We have 3 cats and it has been a struggle to remove the dander and hair that seems to have been common-place until we have used this unit. We give it a two thumbs up for air quality with using this. Recommend purchasing it.
