This is a great product.  I really like the indicator light for air quality.  I am dealing with neighbors that smoke in a poorly insulated apartment and this purifier is exactly what I needed.  I can tell every time my downstairs neighbor smokes and the indicator light turns red moments later - accurate!  I no longer wake up with my eyes, throat, and lungs burning.  I recommend this product for anyone who is sensitive to second hand smoke and other allergens.  Am going to get a larger one for the livingroom!