house and within an hour or so we could already tell a difference. i ran it while we were out running errands and when we got back home the air in our living room felt clean and fresh. i let it run for several days and my entire family can tell a difference in the air quality in our house. our bedroom has always had a stuffy feeling to it so i moved it in there next. after a couple of days it felt like i had opened the windows and let it air out. the air felt so crisp and clean. my boys are not sneezing nearly as much 