[in Japanese]

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There are two kinds of odor emission regulations, what is based on the standards of odor compounds concentrations and on that of the values by the assessment using human nose. The latter one is called “Odor Index regulation” in Japan, and it has advantages such as applicability to all sort of odor, whereas it needs extreme attentions to accuracy control and to safety management. In the year 2002, Odor Index regulation is being applied only to 30% of all odor-regulation designated areas in Japan. Ministry of the Environment Japan (JMOE) is now implementing wide variety of activities to promote Odor Index regulation. And the development of simplified measurement methods, accuracy management procedures, the correspondence to the globalization, etc. are currently ongoing. At the same time, JMOE is conducting the evaluation of deodorization techniques and the disclosure of these information to odor-emitting organizations, and moreover, is supporting the activities to create excellent “scent-environment”.

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Practical reference odors for quality control in olfactometry were developed keeping actual odor index measurement in mind. Pig farm odor and odor of sewage sand sedimentation tank were chosen as reference odors for ambient odor measurement and exhaust odor measurement, respectively. Odor components and the concentrations of odorous substances of these reference odors were determined based on literatures and field measurement data. Reference odors were prepared in gas cylinders. Odor index values of reference odors were determined based on repeated measurement results of odor measurement laboratories. These practical reference odors would be useful for voluntary quality control in the laboratory, interlaboratory comparison, research and investigations.

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Feasibility of four simplified olfactory measurement methods, Paired Odor Bag Method, Four-Sixth Forced-Choice Odor Bag Method, Nasal Ranger^® Method and Six-Points Odor Intensity Scale Method, were investigated for the purpose of coping with malodor complaints by related staffs in local governments with using these simplified methods. A series of comprehensive discussion concluded that Paired Odor Bag Method brought the highest performance, in viewpoints of cost, operational efficiency, consistency of measured values to those of the official method, inter-laboratory data deviation, dispersion of individual olfactory threshold, and data accuracy only by two sniffing panels. Paired Odor Bag Method could acquire approximately equivalent measurement results to those obtained by official method, in conditions of using six sniffing subjects and of applying duplicate measurement for each dilution step.

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In order to achieve a simple on-site Odor Index (10*log (Odor Concentration)) measurements of environmental atmosphere such as the air of the site-borderline of odor-emitting activities, an instrument on olfactometry was developed to perform a series of operation from gas sampling to arranging diluted-samples to be sniffed. Although there are two diluting mechanisms, volumetric and flow-controlling methods, a trial-manufacture of the instrument was made adopting a volumetric type by reasons of its easy accuracy management and of its simple assembly. On-site olfactory measurement was carried out using this instrument, checking the acuity of sniffing panels simultaneously. Consequently, slightly lower values of Odor Index were observed through the measurement, and sufficient correlations were not recognized between these values and those measured by official method. Further improvement of this instrument, a countermeasure to avoid olfactory adaptation of panels’ sense of smell to the site, etc. were pointed out for the future study.

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When novel members are joined into existing concept that was formed artificially, sharing process of this new situation would lead some cognitive modification. In this paper, we regard this modification process as learning.
We utilized odor category of city gas as experimental material for learning and discrimination task for learning, recognition task for performance investigation. At first, participants were instructed that they should discriminate traditional odor quality of city gas from novel odor qualities, and simultaneously memorize these novel odor qualities as “tentative new gas odor” on learning session. After this learning, they were asked to recognize learned new odor qualities as target members from unlearned distracting items. We investigated three aspects as follows, (1) the temporal retention of learning effect, (2) the effect of relearning two months after learning session, and (3) effect by operating a number of repetition of target members during learning and relearning session.
Results showed that it is not easy to add novel members into existing category by once learning nor learning and relearning after two months. There showed, furthermore, possibility of not only keeping novel target members but also adding other distracting items into this category.

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