Odor Identification

Many times odors are associated with chemical contaminants coming from inside or outside the fab manufacturing area. The complexity of the semiconductor manufacturing process coupled with tremendous volumes of air circulation by the vertical laminar flow hoods make the identification of the odor sources very difficult. Also, Ihe use of a wide variety of toxic substances in the process adds to concern by employees in the fab area that unusual odors may indicate a potentially harmful exposure. Often, these odors are transient in nature whichmakes response time a critical element in their identification. 

The following table identifies some of the more common examples of transient odors that may be found in the feb area, and direct reading instruments used to determine the level of IH significance. While direct reading instruments are typically adequate for identifying odors at concentrations that are significant from a health concerns perspective, often the odor threshold for these compounds is less than the detection limit for the instrument. 

Various parent compounds, operating characteristics, and plasma etchers are used in etching operations. This results in diverse concentrations and compounds in the breathing zone of the maintenance technician. Currently no procedure exists to determine what reaction products will form in a particular plasma etcher. Information from past plasma etcher surveys can be used to partially determine a sampling strategy for a particular etch system. However, to a certain extent, each different system must be approached as an unknown. Therefore, two separate surveys are usually necessary to evaluate a plasma etcher maintenance operation. 

Solvent— type (glycol-ethers or photoresists) Combustible gas, photoionization detectors (PID), or infrared detectors 

Corrosive-type (HCl, chlorine, or acids) Detectors tubes or colormetric tape detectors 

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Odor identification by males and females predictions vs. performance. Chemical Senses 7,129-142. 

Coleman E, Goetz RR, Leitman D, Yale S, Stanford A, et al. 2002. Odor identification impairments in schizophrenia ... 

MahadikSP, MukherjeeS, Scheffer R, CorrentiEE, Mahadik JS. 1998. Elevated plasma lipid peroxides at the onset of nonaffective psychosis. Biol Psychiatry 43 674-679. Malaspina D, Coleman E, Goetz RR, Harkavy-Friedman J, Corcoran C, et al. 2002. Odor identification, eye tracking and deficit syndrome schizophrenia. Biol Psychiatry 51 809-815. 

The clue to this transition seems to be found in the sense of olfaction. Early in the course of AD, degeneration occurs in the entorhinal cortex-hippocampal-subicular complex (Price and Morris, 1999). The olfactory bulb, particularly the anterior olfactory nucleus, shows numerous neurofibrillary tangles (NFTs). Odor identification deficits during life may be associated with NFTs in the hippocampus (Wilson et al., 2007). 

Clinically, AD patients consistently show deficits in odor identification compared to controls (Doty et al., 1991). These deficits have been shown to be a true decline in odor identification ability that cannot be explained by lexical difficulty in interpreting written words in the multiple choice test formats. The University of Pennsylvania has developed a smell identification test (UPSIT), with ranges 0-40, which is widely used in clinical settings. Recent studies have shown that odor identification deficits predict conversion fi-om normal to MCI, particularly decline of verbal memory (Wilson et al., 2007). Other series (Devanand et al., 2008a) of studies have demonstrated that olfaction has a strong predictive power of MCI to AD in both types of MCI. Many other biomarkers have been used to predict AD... 

Appearance (physical state, color, odor) Identification... 

Hummel, T., Sekinger, B., Wolf, S. R., Pauli, E., Kobal, G., 1997. "Sniffin Sticks Olfactory Performance Assessed by the Combined Testing of Odor Identification, Odor Discrimination and Olfactory Threshold." Chemical Senses, 22 39-52. 

Doty, R.L., Reyes, P.F. and Gregor, T. (1987) Presence of both odor identification and detection deficits in Alzheimers disease. Brain Res. Bull., IS. 597-600. 

Frohlich (12). After morphine administration some errors in odor identification were made, but the errors were least with disagreeable odors such as garlic, asafetida, and carbon disulfide. All substances seemed to be at a distance even when placed under the nose. Later Wikler, Wolff, and Goodell (5) found that morphine did not elevate olfactory thresholds. 

T. Nakamoto, H. Takagi, S. Utumi and T. Moriizumi (1992) Gas/odor identification by semiconductor gas sensor array and an analog artificial neural network circuit . Sensors and Actuators B, 8,181-6. 

Amoore and Hautala also investigated the effects of distraction (e.g. by work-related tasks) on odor Identification and discovered that, under these conditions, the OSF reached 26 before 50% of subjects detected that the TLV had been attained. In the case of subjects given prior warning, 99% could detect attainment of the TLV at OSF=26. 

Cross-cultural Studies of Sex Differences in Odor Identification... 

We recently sought to determine if the sex difference in odor identification ability observed in American Blacks and Whites (Doty et al., 1984a, b Figure 1) was also present in American Koreans and Native Japanese subjects. In this research, the University of Pennsylvania Smell Identification Test (a 40-item standardized forced-choice test with microencapsulated odors) was administered to 438 Black Americans, 1559 White Americans, 106 Korean Americans, and 308 Native Japanese. The Black and White Americans were comprised mainly of university employees and students, participants in regional health fairs, primary and secondary school students, and youngsters enrolled at summer camps and day care centers. The Korean Americans were part of a Sunday school population at a local Korean church, whereas the Japanese subjects were members of the staff and faculty of a hospital in a medium-sized Japanese metropolitan city (Kawasaki-shi). 

As reported in detail elsewhere (Doty et al., 1985), the women of all four groups outperformed their male counterparts, on the average, to the same general degree (Table 1). Thus, whatever the basis of the sex difference observed in odor identification, it appears to transcend the genetic and cultural differences among these groups. 

Doty, R. L., Applebaum, S. L., Zusho, H., and Settle, R. G., 1985, A cross-cultural study of sex differences in odor identification ability. Neuropsychologia, 23 667. 

Hedner, M., Larsson, M., Arnold, N., Zucco, G. M. and Hummel, T. (2010). Cognitive factors in odor Detection, odor Discrimination, and odor identification tasks. Journal of Clinical and Experimental Neuropsychology, 32, 1062-1067. 

Lehmer, J. R, Gluck, J. and Laska, M. (1999). Odor identification, consistency of label use, olfactory threshold and their relationships to odor memory over the human hfespan. Chemical Senses, 24,337-46. 

Stevens, J. C. and Cain, W. S. (1987). Old-age deficits in the sense of smell as gauged by Thresholds, magnitude Matching, and odor identification. Psychology and Aging, 2, 36-42. 

This paper outlines a microsystem for odor identification and classification A selforganizing artificial neural network (SOM) and a sensor array for gas sensing [1] form the basis of the microsystem It is able to work as a stand alone system, suitable both for industrial and biomedical applications... 

J Pierce, BP Halpern. Orthonasal and retronasal odorant identification based upon vapor phase input from common substances. Chem Senses 21 529-543, 1996. 

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