Development of the Automatic Counting System of Airbone Asbestos Fibers in the Atmosphere.
Grant-in-Aid for General Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||Osaka University|
INOUE Yoshio Osaka Univ., Fac. of Eng., Research Assistant, 工学部, 助手 (60203262)
NAKANISHI Sigeji Osaka Prefectur, Tech. Official, 技師
YAMAGUCHI Katsuhito Osaka Univ., Fac. of Eng., Professor, 工学部, 教授 (90029166)
KAGA Akikazu Osaka Univ., Fac. of Eng., Associate Professor, 工学部, 助教授 (90029265)
|Project Period (FY)
1991 – 1992
Completed(Fiscal Year 1992)
|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1992 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1991 : ¥1,600,000 (Direct Cost : ¥1,600,000)
|Keywords||Asbbestos / Image Processing / Automatic Counting / Visual Counting / Measurement / Chemical Treatment / Heat Treatment / 自動化 / 石綿計測|
We had already developed an automatic counting system to determine the fiber concentration of airborne asbestos in workplace. The aim of this research is develop the method of the application of this system to the measurement of fibers in the atmosphere.
The problems included in the application are as follows:
1) Non-asbestos fibers exist plentifully in the atmosphere.
2) Number concentration of asbestos fibers in the atmosphere is much lower than that in a workplace.
To solve these problems, we propose to use a cascade impactor that is a type of the inertia dust collectors as a sampling device. The method can be used jointly with chemical treatment with an acid or alkali and heat treatment.
The results obtained in this research are as follows:
1) The sampling-air-flow rate of the cascade impactor method can be much higher than that of the membrane filter method. Therefor, sampling time can be shortened.
2) Fine particles that mask asbestos fibers on a filter are removed from samples.
3) Cotton and synthetic fibers which occupy the majority of airborne fibers in the atmosphere can be removed by chemical and heat treatment in the arrangement of specimen.
4) The collection efficiency of our test impactor which has serial four stages was 90% or more.
We checked the performance of our counting system through the comparison with visual countings. The same specimens were counted by the system and six visual counting laboratories, and their counting values were compared mutually. As the result, the maximum to minimum ratio of the counting values was about five. Therefor, there seem to be some significant differences among the counting standards of each laboratory. Moreover, it is found that the visual counting men have a tendency to count fibers only thinner than about 1.5 microns in average deameter instead of legal threshold 3.0 microns.
Research Output (6results)