Aerosol underground measurements

Khan, A., F. Bandi, C.R. Phillips and P. Duport, Underground Measurements of Aerosol and Radon and Thoron Progeny Activity Distributions, to be published in Proc. 191st American Chemical Society National Meeting, New York, April 13-18 (1986). 

Underground Measurements of Aerosol and Activity Distributions of Radon and Thoron Progeny... 

The aerosol distributions are calculated in terms of a single mode, without attempting to resolve them into a major large mode and a minor very small (unattached) mode. The unattached mode is very much smaller in diameter (of molecular cluster dimensions) than the major mode of the aerosol and in underground mines its peak height is very small. To resolve such a mode would require more than the three diffusion batteries used for the measurements. 

Figure 5.6 shows the unattached fraction of radon (/ ,Rn) and thoron (/p,Tn) decay products as a function of the particle concentration of atmospheric aerosols. The fp values as a function of the particle concentration, Z, are measured by means of a condensation nuclei counter (CNC). Many working places have aerosol sources due to human activities and combustion and technical processes with a high particle concentration, Z > 4 X 10 particles cm , and therefore fp values below 0.01. The fp values are higher than 0.1 for places with particle concentrations <4 x 10 particles cm . This is the case in poorly ventilated rooms (ventilation rate <0.5 h ) without additional aerosol sources, rooms with an operating air cleaner and poorly ventilated underground caves. For the unattached thoron decay products in indoor air, the unattached fraction is estimated by the equation... 

Cantrell, B.K., and K.L. Rubow. 1992. Measurement of diesel exhaust aerosol in underground coal mines. In Diesels in Underground Mines Measurement and Control of Particulate Emissions. Proceedings Bureau of Mines Information and Technology Transfer Seminar. Minneapolis. September 29-30. 

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