[' ', ' ', 'Human', 'Responses', 'to', 'Propionic', 'Acid', 'Vapor', 'MARTIN', 'KENDAL-REED’', '&', 'JAMES', 'C.', 'WALKER?', '(‘University', 'of', 'North', 'Carolina,', 'Chapel', 'Hill,', 'NC;', '?R', 'J.', 'Reynolds', 'Tobacco', 'Company,', 'Winston-Salem,', 'NC)', 'In', 'each', 'of', 'four', '50-trial', 'sessions,', 'ten', 'subjects', '(5', 'male,', '5', 'female)', 'were', 'presented', 'with', 'clean', 'air', 'controls', 'and', 'a', 'range', 'of', 'four', 'logarithmically-spaced', 'concentrations', '(0.08', 'to', '80', 'ppm)', 'of', 'propionic', 'acid.', 'This', 'range', 'was', 'selected', 'to', 'extend', 'from', 'below', 'the', 'olfactory', 'threshold', 'to', 'above', 'the', 'trigeminal', 'threshold.', 'Breathing', 'data', 'were', 'collected', 'in', 'successive', '15', 'sec', 'periods', 'just', 'before', 'and', 'during', 'stimulus', 'presentation,', 'after', 'which', 'the', 'subjects', 'entered', 'ratings', 'of', 'odor', 'strength', '(OS),', 'nasal', 'irritation', '(NI),', 'annoyance', 'and', 'acceptability', 'on', 'unstructured', 'line', 'scales.', 'Threshold', 'estimates', 'were', 'computed', 'for', 'each', 'session.', 'These', 'were', 'used', 'to', 'examine', 'session-to-session', 'fluctuations', 'in', 'perceptual', 'and', 'respiratory', 'responses', 'for', 'each', 'subject', 'and', 'to', 'assess', 'inter-subject', 'variability', 'in', 'sensitivity,', 'For', 'OS,', 'NI,', 'and', 'tidal', 'volume', '(TV;', 'the', 'total', 'volume', 'of', 'air', 'inhaled', 'during', 'odorant', 'presentation)', 'the', 'within-subject', 'range', 'of', 'thresholds', 'averaged', '0.20,', '0.96', 'and', '0.90', 'log', 'unit;', 'respectively.', 'Mean', 'thresholds', 'were', 'computed', 'for', 'each', 'subject,', 'based', 'on', 'the', 'four', 'test', 'sessions,', 'and', 'exhibited', 'the', 'following', 'inter-subject', 'spans:', 'OS:', '0.09', '-', '0.23', 'ppm;', 'NI', '0.08', '-', '1.66', 'ppm;', 'TV', '0.60', '-', '75.91', 'ppm.', 'These', 'results', 'will', 'be', 'discussed', 'in', 'terms', 'of', 'the', 'value', 'of', 'tidal', 'volume', 'as', 'a', 'measure', 'of', 'trigeminally', 'mediated', 'nasal', 'irritation', 'and', 'the', 'minimum', 'amount', 'of', 'testing', 'needed', 'to', 'characterize', 'individual', 'sensitivity', 'to', 'odorants', 'or', 'irritants.', '.', 'Supported', 'by', 'a', 'gift', 'from', 'R.J.', 'Reynolds', 'Tobacco', 'Company', 'and', 'NIH', 'grant', 'DE06957.', 'SB', 'ee', 'ecm', 'den', 'subjetts', 's&', 'St', 'Loe', 'PY', '“4', 'aw', 'uve', 'CEA', ',', 'prepritine', 'a', ';', 't-te', '—', 'Uh', 'Stade.', 'ke', '“ves', '9@7S', 'O9LTS']