I bought mainly because of its sustainable, energy-efficient qualities and clean aesthetic but am wowed by how effective it really is.  Using the auto setting, it really does adjust and within minutes restores the air back to a quality level (noticeably different after cooking odors waft into my room and then are removed by PURE!).  It does generate a slightly louder whirring when it has more to purify in these cases but is so quick that it's not a bother.  Thankful for such a thoughtful and effective product!