1963 Volume 12 Issue 11 Pages 1053-1057
This study was carried out using the British Standard deposit gage (BG), a wet modification of BG (wet BG), and the dust jar recommended by the Pharmaceutical Society of Japan (DJ), at 4 stations in Tokyo city. The deviation coefficient (d) used by the authors to show the reproducibility was the following,
d=|m-a|/m×100=|m-b|/m×100,
where, a, b, …… measured value of one material,
m=a+b/2
There were stational, monthly and instrumental fluctuations in the deviation coefficient, although d by the same instrument was about 25% in the annual mean and was distinctly smaller than d between different kinds of instrument which was usually over 20%. Among 3 dust collectors tested, BG tended to give the largest d.
As collective conclusions from their 3 successive reports remarkable and irregular differences were seen between BG values and the other two in the amount of deposition (average annual values by the latters were 1.52 times greater than the former) as well as in its composition. The differences were seen in every places, and in every months or years. Meanwhile, the DJ and the wet BG methods gave values in good agreement, and generally with higher reproducibility than the BG method.
DJ is much easier in the practical oper than BG, and by the use of DJ, they can avoid accidental errors caused by meteorological conditions, especially by the wind, which are almost unavoidable in BG. Thus, DJ should be recommended as the dust collector instead of BG. The adoption of the DJ or wet method is essential in the measurement in rainless season in large city with multiple smoke sources.
