Evaluation Model of Suspended Particulate Matter using the Sequential Sampling Method

<p>In Japan, the mass concentration of suspended particulate matter (SPM) in rooms must be maintained under 0.15mg/m³ according to the Building Sanitary Law. On the other hand, the average SPM mass concentration of buildings in Tokyo city is approximately 0.008~0.012mg/m³, which is considerably lower than the value accepted by this law. In general, temporal inspection is carried out for a duration of approximately 5 min., and if the average concentration is less than the regulated value, the room is judged as sufficiently clean. However, a period of 5 min is not enough to obtain a statistical sample, and a judgement based on this measurement has no statistical meaning. In this study, the distribution of the SPM mass concentration was investigated though an actual survey, and a statistical temporary distribution model was suggested. Based on the results of this survey, a model to judge the SPM concentration was suggested by using the sequential sampling method. Moreover, the proposed model was verified using Monte-Carlo simulations. The results are as follows; 1) Poisson distribution was developed with the trends in the temporal SPM concentration fluctuation, 2) An SPM concentration judgement model was developed by using the sequential sampling method, 3) The significance of this model was confirmed using Monte-Carlo simulations, 4) According to this model, the concentration of SPM in ordinary rooms can be judged to be acceptable or not according to the regulation in a few minutes.</p>