The VOCs sampled in a newly-built house were determined to belong to a certain number of types when their pattern of concentration was studied; VOCs change their concentration pattern over a long period of time. In this paper, we aim to classify VOCs into three pattern groups, on the premise that those VOCs showing similar transition characteristics must belong to the same group. We respectively selected a representative compound for each classified type in order to verify the process of transition statistically with a view to proposing a new method creating a representing index of VOC concentration indoors, which, we believed, would contribute to precise evaluation of the degree of air pollution. As a result, we obtained three types of groups described below :
Type 1 : VOC concentration, relatively high at the time of the completion of the house, rapidly decreased its concentration thereafter.
Type 2 :. VOC concentration, relatively low at the time of the completion of the house, tended to decrease overall although a process of increasing and decreasing had been repeated in the meantime.
Type 3 : Some VOCs we measured showed a single peak at a certain time during our measuring period.
Our method was verified to have statistical significance. Ethylbenzene was selected as the compound representing Type 1 and styrene as representing Type 2. Classifying VOCs into different groups and selecting those representating respective groups from the viewpoint of their pattern of concentration transition should be considered a significant method.
