Equilibrium factor aerosol sources

The paper summerizes the experimental data on the equilibrium factor, F, the free fraction, fp, the attachment rate to the room air aerosol, X, the recoil factor,, and the plateout rates of the free, qf, and the attached, q3, radon daughters, determined in eight rooms of different houses. In each room several measurements were carried out at different times, with different aerosol sources (cigarette smoke, stove heating etc.) and under low (v<0.3 It1) and moderate (0.3[Pg.288]

The mean value of the equilibrium factor F measured in houses without aerosol sources was 0.3 t 0.1 and increased up to 0.3 by additional aerosol particles in the room air. The fraction of the free radon daughters had values between fp = 0.06-0.13 with a mean value near 0.1. Only additional aerosol sources led to a decrease of f - values below 0.05. 

The equilibrium factor F in low ventilated rooms without aerosol sources varied between 0.2 and 0.4 (Table la) with an average value near 0.30 a similar value as reported by Keller and Folkert, 1983, and by Wicke and Porstendorfer, 1982. In rooms with additional aerosol sources an average F-value between 0.4 and 0.5 was obtained (Table III). An error of about 20 % can be estimated for the equilibrium factor. 

Table III. The aerosol particle concentration (Z), the equilibrium factor (F), the free fraction (fp), the attachment parameters (X,B,d), the plateout rates (qf, qa) and the recoil factor (ri), obtained in lowly ventilated rooms with aerosol sources.

The mean value of the equilibrium factor F in houses i/as 0.3 0.1 without aerosol sources and can increase up to 0.3 with cigarette smoke in the room air. 

Then the unattached fraction was calculated in each measurement and was found to be between. 05 and. 15 without aerosol sources in the room and below. 05 in the presence of aerosol sources. The effective dose equivalent was computed with the Jacobi-Eisfeld model and with the James-Birchall model and was more related to the radon concentration than to the equilibrium equivalent radon concentration. On the basis of our analysis a constant conversion factor per unit radon concentration of 5.6 (nSv/h)/(Bq/m ) or 50 (ySv/y)/(Bq/m3) was estimated. 

Table II shows the nominal alpha dose factors for occupational mining exposure. Table III shows the alpha dose factors for the nominal environmental situation. Table IV shows the bronchial dose factors for the smallest sized particles, that dominated by the kerosene heater or 0.03 pm. particles. The radon daughter equilibrium was shifted to a somewhat higher value in this calculation because this source of particles generally elevates the particle concentration markedly with consequent increase in the daughter equilibrium. Table V shows the alpha dose for a 0.12 pm particle, the same as the nominal indoor aerosol particle, but for a particle which is assumed to be hygroscopic and grows by a factor of 4, to 0.5 pm, once in the bronchial tree.

There are two distinct situations for uranium exposure environmental and occupational. A population inhales and ingests fairly constant daily quantities of uranium from natural, local airborne, and dietary sources. This results in an equilibrium or steady-state condition for the intake and excretion of uranium. In the occupational circumstance, the quantity of the material, type of exposure (acute or chronic), exposure route, aerosol particle size, solubility class, biological half-times for elimination are some factors that influence the metabolic fate of the uranium. 

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