Abstract
The dust samples collected from 6 a.m. to 10 p.m. by the Owen's jet in the open air and in rooms were determined the particle-size distribution in use of the microprojector. As the result, it is ascertained that by the distribution curves of particle-size every hour shown in Fig. 1 (a)〜(l), the distribution curves of particle-size of indoor dust are similar to the curve of outdoor dust, and the deviations in each distribution every hour are very small. So the average distribution curve of each time is almost equal as Fig. 2. While, about fallen dusts in the room diameters of particles were measured with same aparatus, and the distribution curves at every 10cm distance from window are shown as Fig. 4 (a)〜(e). Fig. 6 or 7 shows the relation between the ranges of particle-size of fallen dusts and the distance from window. As another method of treating the data is to plot the cumulative percentage of particles for the different class intervals, percentage less than a stated size, against the size on normal probability paper, logarithmic probability paper and Rosin-Rammler distribution paper, and draw the best straight line through the points. From this line, which distribution curve assumes the data is considered.
