I don't quite understand the conclusion of this study (or at least, the comment by Paul Hunter at the end, which may be an outside comment and not the result of the study)?
5 minutes is a really long time for air circulation. The standard requirement for air circulation in offices and stores is 4 changes/hour (so more or less all the air in the room is replaced every 15 minutes).
Air within a room circulates much faster than that (compared to how fast it is being pushed in and pulled out by the small fans at the corners). For comparison - think about standing in one side of a room when somebody sprays perfume on the other side - you will notice in way less than 5 minutes.
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