An olfactory method for simultaneously assessing a quantity and a quality of odors in an airstream, comprising the steps of determining a first mean value of results of ratings of an acceptability of an
odor of a single airstream, rated by a group of test persons; determining a second mean value of results of ratings of an odour intensity done by the same group of test persons for the same odorous airstream; determining a decipol value of ratings of a perceived air quality according to the method of Fanger of the same odorous airstream, rated by the same group of test persons; providing a matrix containing all mathematically possible values of the acceptability of rating, the
odor intensity rating and the decipol values of the perceived air quality, wherein each value or a range of values of one the three rating categories is assigned to one
score in a scale of scores: determining a
score for each of the values taken from steps a), b), and c) by classifying it into one of the values or ranges of values in a corresponding category in the matrix of step d), which results in three scores; and calculating a third mean value of the three scores, resulting in an overall average
score corresponding to an overall quantitative and qualitative
odor characteristics of the airstream evaluated.