Radon zones

MAP 31.1 United States map of radon zones. (Adapted from U.S. EPA, EPA Map of Radon Zones, EPA-402-F-93-013, U.S. Environmental Protection Agency, Washington, DC. Available at http //www.epa.gov/ radon/zonemap.html, February 2009.)... 

A FIGU RE 21.26 EPA map of radon zones in the United States. The color coding shows average indoor radon levels as a function of geographic location. 

A fijll-page version of the Radon Zone Map is available at the EPA radon web site, http //www.epa.gov/radon/ zonemap.html. What are the predicted average indoor radon levels for the counties where your college and home are located If the munbers are low, does this mean you do not need to worry about radon exposure ... 

Zone 1 Counties that have a predicted average indoor radon screening level greater than 4pCi/L (picocuries per liter)—the highest potential. 

Radon (Rn-222) daughter exposure at home is a potentially significant contributor to background lung cancer rates. In western countries, an increase in the number of energy-efficient homes threatens to increase the exposure of the occupants to radon and its decay products by reducing ventilation rates. This is also true in Japan, especially in winter. Japan is situated in the temperate zone, which results in a rather long hot and humid summer climate. Consequently,... 

Fig. 3. Backscattered electron image of a zoned murataite-5C crystal in a Synroc-type ceramic containing 20 wt% HLW surrogate produced by ICCM at SIA Radon (Sobolev et al. 1997c). Scale ban 5 pm. Numbers mark locations of analyses listed in Table 3. ACT concentrations in the core are approximately 10-20 times higher than at the edge.

The amount of radon that enters a building depends on the geology of the zone, the concentration of the gas, the pathways into the building and its ventilation rate. The US EPA recommended limit indoor radon concentration is 4 pico Curies/L. 

Martins C., Kipphut G. W., and Klump J. V. (1980) Sediment-water chemical exchange in the coastal zone traced by in situ radon-222 flux measurements. Science 208, 285-288. 

Chalov, P.I., Tuzova, T.V. and Alekhina, V.M., 1976. Fluctuations of helium and radon anomalies in some springs located along faults of the north Tien-Shan seismic zone during the period preceding the Kochkor earthquake of 1974. Dokl. Akad. Nauk SSSR, 231 26-28. 

Yasko, V.G., 1981. Radon in spontaneously-evolving gases of hot springs of the Baykal rift zone. Dokl. Akad. Nauk. SSSR, 245 124-126. 

Burnett, W. C. and H. Dulaiova. 2003. Estimating the dynamics of ground water input into the coastal zone via continuous radon-222 measurements. J. Environ. Radioactivity 69(l-2) 21-35. 

Zone 2 Predicted average indoor radon screening level between 2 and 4 pCi/l Zone 3 Predicted average indoor radon screening level less than 2 pCi/L... 

The migration of gas becomes an important consideration in certain geoenvironmental engineering applications when the gas content in a porous medium is sufficiently high such that the gas phase is continuous. Examples of such apphcations include the removal of VOCs and SVOCs from the imsaturated or vadose zone above the water table in the subsurface via the gas phase and the minimization of oxygen influx or radon efflux from engineered covers for tailings disposal applications. In the former case, removal efficiency is improved as gas permeability increases, whereas in the latter case, the objective is to minimize the gas permeability and therefore minimize the gas flow. 

Natural distributions of elements in subsurface geologic formations can give rise to ground water or soil zone contamination. Two examples of note are the generation of radioactive decay products (e.g., radon gas, radium) from natural thorium and uranium, and the release of naturally occurring arsenic or selenium from earth materials. 

This EPA map shows predicted average indoor radon levels for all Untted States counties Zone 1, >4 pCi/L Zone 2,2-4 pCi/L Zone 3, <2 pCi/L. Homes in the lower zones are not necessarily safer houses with elevated radon levels have been found in all three zones. 

A Map of the United States showing radon levels. Zone 1 counties have the highest levels, and zone 3 counties have the lowest. 

Based on results from Texas and Wyoming, radiogenic radium and radon are excellent short-range indicators of uranium mineralization. Radon greaterthan 1000 pCi/l may indicate zones of economic significance. ... 

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