On Atmospheric Smoke Pollution observed by Air Filter at Oosaka

[摘要] This paper treats the atmospheric smoke pollution in Oosaka observed by an “Air Filter”. This instrument is devised so as to get automatically a continuous record of the amount of sooty suspension in the air. Air is sucked through a small hole across which a sheet of filter paper is transversally moved so that a blackened line of smoke particles (shade) is obtained on it.The observation was continued about a year at two places, Katuyama and Namba in Oosaka. The former place is in the eastern suburb and the observation was made at the Oosaka Branch of Cent. Met. Obs., while the latter is in the central part of the city. The observed shades were estimated hourly comparing with the standard scale of shade. The standard scale was newly made for this investigation by a photometrical method from 0 (perfect white) to 20 (perfect black). This scale is not always linear to the amount of sooty suspension, as the scale 1 corresponds to an amount of 0.08mg per m3, 5 to 0.96 and 10 to 39mg per m3.The main results obtained are as follows:-(i) Annual variation shows a maximum in Nov. and a minimum in May. See Fig. 2.(ii) Hourly variation shows two maxima, one in the forenoon (about 7h) and the other in the evening (about 19h). See Fig. 4.(iii) Sundays and holidays show a little diminution of pollution.(iv) Amount of pollution is on the average twice in the central part compared with that in the suburb.(v) Hourly change of pollution is closely similar at two places.(vi) The pollution diminishes remarkably as the wind velocity increases.(vii) The sun-shine also diminishes the pollution as it causes the convection in the lower atmosphere.(viii) The precipitation surely cleans the atmosphere, but this fact can not be observable so definitely in the air near the surface.(ix) The variation of the smoke-amount according to the wind direction is not so noticeable in the present investigation.

[学科分类] 大气科学