Comparison between the British Standard deposit gage and dust jar

Differences of amounts of deposited impurities obtained by the British Standard deposit gage and dust jar.I

Abstract

The study was carried out on the roofs of buildings at 3 stations in Tokyo city from July 1958 to June 1960. The British Standard deposit gage (BG) and the dust jar recommended by the Pharmaceutical Society of Japan (DJ) were used as dust collectors. The latter had been devised by I. Saito, one of the authors.
There were remarkable differences in the amounts of pollutants between BG values and DJ values, where the latters usually 150200% greater than the former in annual mean values. There were little monthly changes in BG values, while DJ values rose up eminently in the cold season. Consequently, BG values were close to DJ values in the warm or hot season, and were much lower than DJ values in the cold season.
The increase of total amount of deposit was produced chiefly by the increase of its waterinsoluble matter. Seemingly, the amounts of deposit were little changed by the difference of ca. 1 m of the height of the upper surface of the dust collector for the floor. As the cause of these marked differences between BG values and DJ values, the authors assumed, considering seasonal meteorological conditions in Tokyo, the difference of sampling method, namely, the difference of "dry" BG method and "wet" DJ method.