Making mitigation decisions based on short-term tests of 222Rn.

One test option recommended by the EPA for deciding to mitigate involves up to two short-term measurements. If the initial measurement is > or = 148 Bq m-3, the test is repeated and the house is mitigated only if the mean of the two measurements is > or = 148 Bq m-3. The frequency of errors under this test option was evaluated using 2-d and 1-y measurements from 1,449 houses. The chances of making incorrect mitigation decisions vary from 1% to more than 50%.