We have 3 cats. We purchased the BreathSmart system for friends and family member who suffer from many alergies, including cats. Our friends spent 3 1/2 hours at our house, unmedicated, to test out the system. They had absolutely not problems at all. I have to admit we were not confident it would allow them to be symptom free. It was a wise investment. Not only were they comfortable but our house was dust free.