We purchased this purifier just in time. I love it. It tells us just how bad our air is and then when it's finally purified the air enough to breathe. We've started running it all day long in the rooms we spend most of our time - the kitchen and sitting room. We used it during our 'Mars' orange sky day and will keep it running until our spare-the-air days (we're in our 26th day) are over. It actually does a good job of clearing most of our house. Again, love this purifier.