My wife suffers from numerous allergies including dust and pollen. Spring is an especially difficult time for her. I purchased the BreatheSmart unit for our large great room but was concerned one unit would not be sufficient. After running the unit for just 8 days my concern has been alleviated. With the unit set on speed 3 it keeps our great room air clear of dust and other allergens including the spring time pollen that is in full bloom right now. My wife's allergies have been greatly relieved. I recommend this unit to anyone who suffers from air borne allergens or just wants to enjoy filtered air in the home.