I got the Shark HP 102 Air Purifier for my kitchen/den combination where we spend most of our days. We also have double doors opening to the backyard. So we get a lot of dust, and smoke in that large room.  I found that the unit is very powerful and actually shows me the three different air qualities at one glance: Good, Fair, and Poor.  The large visual display shows us exactly the percentage of air quality in the room.  
Last week, in preparation for the holiday, I cooked quite a bit every day and the air purifier would show exactly how the air was affected by the cooking, then began clearing it to 100% perfection. It is extremely quiet and works continuously.  Very pleased to have gotten this Air Purifier.