This is a question for my anatomy and physiology class. We are studying olfaction and gustation.

Here is from a source that is easier to understand then your typical science journal... I can see why you would ask. The language can be complicated in some of the studies.


... mechanical stimulation from sniffing might enhance neuron activity and thus boost nasal sensitivity, especially when scents are faint. Airflow into the nose might help rouse neurons enough to help detect faint odors that the neurons had previously failed to detect in an unaroused state.
Sniffing the air helps us smell better - LiveScience- msnbc.com (http://www.msnbc.msn.com/id/17631787/)

Or it could be that sniffing simply brings in more of the air carrying the scent, but I'll buy that it might also stimulate neurons too.