Weave been looking at air purifiers for a while. There are so many out there! Shark has always been a reliable product so we gave it a shot. So glad we went with a brand we knew! My grandson has major allergies. I dusted, vacuumed and washed all bedding before setting this up. When I turned the air purifier on, it still said 81%. I heard it running but it was so very quiet you had to be close and really listen. I left the room and 20 minutes later it said 99%. Now it stays on in his room and it’s almost always either 99% or 100% though I have seen it drop when he comes in after school changing clothes and such. He even checks the pretty blue display and tells me the numbers. No more sneezing and congestion every morning! He used to wake up and immediately sneeze and be so stuffed up. We are so happy he wakes up breathing fine, no dark circles under his eyes either. Excellent product!!