THE NATURE AND DURATION OF ADAPTATION FOLLOWING LONG-TERM ODOR EXPOSURE

Any individual living or working in an odorous environment can experie nce changes in odor perception, some of which are long lasting. Often, these individuals report a significant reduction in the perception of an odor following long-term exposure to that odor (adaptation). Yet, most experimental analyses of olfactory adaptation use brief odorant e xposures which may not typify real-world experiences. Using a procedur e combining long-term odor exposure in a naturalistic setting with psy chophysical tests in the laboratory, we present evidence to show that reduced odor intensity following long-term exposure is accompanied by odorant-specific shifts in threshold. Subjects were exposed continuous ly to one of two odorants while in their home for a period of 2 weeks. Exposure produced an odorant-specific reduction in sensitivity and pe rceived intensity compared with preexposure baselines: Detection thres holds for the adapting odorant were elevated following exposure and pe rceived intensity ratings for weak concentrations were reduced. For mo st individuals, reduced sensitivity to the test odorant was still evid ent up to 2 weeks following the last exposure. The persistence of the change, as evidenced by the duration of recovery from adaptation, dist inguishes this phenomenon from the adaptation seen following shorter e xposures and highlights the need for the study of exposure durations t hat are more similar to real-world exposures.