Dennis Shusterman, MD, MPH

Research Tools: Sensory Testing (Nasal trigeminal)

Carbon Dioxide (CO2) Detection

Carbon dioxide is an odorless gas that produces nasal [or ocular] discomfort by virtue of its hydration to carbonic acid in mucous membrane water. Because it is odorless, CO2 detection thresholds can be obtained by asking subjects to identify the more irritating stimulus when CO2 pulses are alternated with pulses of pure air.

VOC Localization

VOCs (volatile organic compounds) have both odorant and irritant qualities. Because of this fact, odor cueing must be avoided in any threshold test of nasal irritation. This can be accomplished by performing the so-called localization (or lateralization) test, in which the subject indicates which side of the nose is irritated when a given concentration of VOC vapor (stimulus) and water vapor (control) are applied simultaneously to opposite sides of the nose. This task exploits the fact that the brain can reliably discriminate the laterality of nasal irritation - but not olfaction.