We live in an older house and have had mold issues. With this comes sinus problems and cold like symptoms. This filter has been able to clear and clean the bedrooms with no more lingering issues. It took about 24 hours for the first room, kept on high, then runs 24 hours a day on a low setting to have a better smell and clear sinus symptoms. The second room, a little larger, took about 3 days on high and runs on medium continuously. There is some initial factory smell that quickly dissipates and if you aren't used to having white noise, it might be bothersome, especially on high; however if you do like the noise its a very soothing sound.