History of Radon in Nevada
Nevada conducted radon surveys in 1989 and 1990-1991 to determine the extent of elevated radon concentrations in homes.
In the 1989 survey, 307 homes were evaluated utilizing short-term radon detectors. Of the 307 homes, 20 percent exceeded the EPA recommended remedial action level of 4 pCi/l of air. This compared closely to the later and more extensive survey of 1990-1991. In the latter survey, 2,048 homes were surveyed and the remedial action level was exceeded in 19 percent. However, on the basis of numbers of households, population centers were sampled less intensively than rural areas. For example, only 12 percent of the homes sampled were in Clark County where more than half of the state's population lived. When weighted to compensate for variability in sampling intensity (giving more weight to urban data), the data indicate that about 10 percent of Nevadans live in houses with radon levels exceeding 4 pCi/l.
It should be noted that radon concentrations in homes do not follow neighborhood, city or county boundaries and that many communities in the state have grown beyond the 1990-1991 boundaries possibly into areas more susceptible to elevated radon concentrations.
EPA Map of Radon Zones in Nevada
From the 1989 and 1990-1991 radon surveys, the EPA determined three zones for each state: Zone 1, greatest potential for elevated radon levels; Zone 2, moderate potential; and Zone 3, lowest potential for elevated radon levels. However, elevated radon levels can be found even in Zone 3 areas. The only way to determine whether a house has elevated radon levels is to test.
- Zone 1 counties have a predicted average indoor radon screening level greater than 4 pCi/L (red zones)
- Zone 2 counties have a predicted average indoor radon screening level between 2 and 4 pCi/L (orange zones)
- Zone 3 counties have a predicted average indoor radon screening level less than 2 pCi/L (yellow zones)