Design of a 1-Butanol Scale Dynamic Olfactometer for Ambient Odor Measurements

Abstract

ABSTRACT A portable system has been developed for quantifying odors in atmospheric air. Panelists compare the intensity of ambient odors with the intensity of discrete levels of 1-butanol provided by the olfactometer. Range of delivered 1-butanol concentrations is 0 to 80 ppm in air at a flow rate of 15 L/min. Laboratory tests have been performed to ascertain precision, panelist response, variability between two olfactometers, and effect of delivery method (ascending, descending and random odor presentation). Nineteen panelists made determinations of comparative odor intensities from two identically constructed olfactometers, where one unit provided a set concentration of 1-butanol and the second provided variable concentrations to the panelists. At a given set concentration the panelist would be exposed to a sufficient number of intensities from the variable-output system such that a decision could be made on the match of intensities. Totally, 855 data points of matched intensities were acquired in the study. For the entire data set the mean value of the ratio of measured concentration to set concentration was 0.984. The geometric standard deviation of the concentration ratios was 1.44. INTRODUCTION Odor complaints are the most frequent problems for air pollution control agencies; for example, during 1981 the Texas Air Control Board received 1,467 complaints of which 51% were related to odors. Fourteen percent of these odor complaints were related to agricultural sources (Bradford, 1982). There are two techniques which agencies presently use.