I suffer from asthma and bad allergies, every morning I'd wake up feeling stuffed up and sluggish. Always taking a long while to breath normally. First day I got my air400 I put it on max in my room that's 250 sq ft. Within an hour quality went from alright to incredible! First morning I woke up clear headed, feeling amazing! Could run miles if I really wanted too! Honestly the best investment I've made! Even if your air quality is pretty good, take it up a notch!