A Bisensory Method for Odor and Irritation Detection of Formaldehyde and Pyridine

Abstract

A bisensory method was developed for determining the psychometric functions and absolute thresholds for odor and sensory irritation of two odorous irritants. Individual and group thresholds for formaldehyde or pyridine were measured for 31 age-matched subjects (18–35 years old). P 50 absolute thresholds were for formaldehyde odor 110 ppb (range 23–505), for pyridine odor 77 ppb (range 20–613), and for pyridine irritation 620 ppb (range 90–3,656); too few subjects’ formaldehyde irritation thresholds were possible to determine (human exposures limited to 1 ppm). In spite of large interindividual differences, all thresholds for irritation were higher than for odor. The average slopes of the 62 psychometric functions for odor and the 32 possible for sensory irritation were highest for formaldehyde odor (83% per log ppb) and equal for pyridine odor and irritation (68% per log ppb). The bisensory method for measuring odor and sensory irritation jointly produced detection functions and absolute thresholds compatible with those earlier published; however, a steeper slope for sensory irritation than odor was expected for pyridine. The bisensory method is intended for measuring odor and sensory irritation to broadband mixtures and dynamic exposures, like indoor air.