I still saw dust on my furniture, but when the big light on the purifier turned orange I took the filter out, and it was covered in dust. Since, it wasn't 3 months quite yet, I did not have a replacement filter. So, I took a very gentle brush and swept the filter off, careful not to get anything on the inner surface, and put it back in. By the time the replacement arrived, it was covered again! I must have a VERY dusty house!!! (We have 2 dogs.)