Risk Assessment of Radon in Drinking Water (1999) / Chapter Skim
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3 Transfer of Radon from Water to Indoor Air
3 Transfer of Radon from Water to Indoor Air
Pages 50-58
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From page 50... ...
The amount of waterborne radon escaping into the air is different throughout a dwelling but is higher in areas of active water use such as bathrooms and kitchens. It also depends on the radon concentration in the water and the activities that are taking place.
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From page 51... ...
in the literature, and most of them refer to a limited number of geographic areas. Thus, there is considerable uncertainty in the extrapolation of the resulting distribution to the entire housing stock of the United States.
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From page 52... ...
When plotted on a logarithmic scale, the central portion of the distribution is fairly linear and thus the geometric properties have also been calculated. The geometric mean is 3.8 x 10-5 with a geometric standard deviation (GSD)
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From page 53... ...
~McGregor ~ 1 1 1 1 1 1 10 30 50 70 90 99 99.9 Probabilil3r 53 FIGURE 3.1 Cumulative probability distribution of measurements of transfer coefficient. use, and use-weighted transfer efficiency are lognormal and so can be combined as done by Nazaroff and others (1987~.
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From page 54... ...
This study provided mean ventilation rates for each county in the country. Sherman and Matson estimate the number of houses of various types and sizes in each county in the United States by using data from the 1990 national census and the same DOE survey used to estimate
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From page 55... ...
Because the Murray and Burmaster approach was to estimate the distribution over the entire housing population, the committee adopted their GSD to propagate into estimates of the geometric mean and standard deviation of the transfer coefficient. Using the Sherman and Matson model arithmetic mean and a GSD of 2.3 implies a geometric mean of about 0.77 air changes per hour.
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From page 56... ...
Hi a_ o :~: ED : 0. 1 1 ~1 1 f / :/ ; / / f / / / / 1 ~1 1 1 , ' 1 1 10 30 50 70 90 Probabiblty gg 99.9 go.-" FIGURE 3.3 Cumulative probability distribution of water use per day per person based on data from Boulder, CO; Denver, CO; Eugene, OR; Seattle, WA; and San Diego, CA.
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From page 57... ...
TABLE 3.1 Lognormal Distributions of Parameters in Transfer-Coefficient Calculation Nazaroff and others (Nazaroff and others 1987) Parameter Geometric Mean Committee Geometric Standard Deviation Geometric Mean Geometric Standard Deviation Dwelling volume per occupant (m3 person-1)
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From page 58... ...
Considering the problems with both the measurements of the transfer coefficient and the measurements that are the input values for the model, the committee recommends that the Environmental Protection Agency continue to use 1.0 x 10= as the best central estimate of the transfer coefficient, based on the available data. Because of the uncertainty in the value of the ventilation rate and its distributional characteristics, the committee recommends assuming that the transfer coefficient is between 0.8 and 1.2 x 10~.
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