Figure 1.
Three routes of odor transport and relation to lung retention.
MLN: mouth-lung-nose, where odorants enter via the oral cavity. This is most common during smoking or breathing with open mouth. Lung retention occurs.
NLN: nose-lung-nose, where odors enter via the nose. This occurs commonly during orthonasal smell while sniffing or breathing with closed mouth. Lung retention occurs.
MN: mouth-nose, where odors originate in the oral cavity and pass directly to the nose. This is typical of retronasal smell during food intake. Lung retention does not occur.
OE: Olfactory epithelium.
