Interpreting Radon Test Results
- If the short-term test result is 4 pCi/L or higher, conduct a follow-up test to confirm the results.
- Follow-up with either a long-term test or a second short-term test.
- For a better understanding of the home's year-round average radon level, take a long-term test.
- If results are needed quickly, take a second short-term test.
The higher the initial short-term result, the more certain the homeowner can be to conduct a short-term rather than a long-term follow-up test. If the first short-term test result is several times the action level - for example, about 10 pCi/L or higher - a second short-term test should be taken immediately.
If the long-term follow-up test result is 4 pCi/L or more, fix the home.
If the homeowner followed up with a second short-term test: the higher the short-term results, the more certain the homeowner can be that the home should be fixed. The homeowner should consider fixing the home if the average of the first and second test is 4 pCi/L or higher.
Basis for the 4 pCi/L Radon "Action Level"
No radon level is considered "safe". The risk of developing lung cancer is directly proportional to the levels and duration of exposure to radon: the higher the radon concentration, the higher the lung cancer risk. The 4 pCi/L "Action Level" is based on current mitigation technology. Today, mitigation technology can almost always reduce high radon concentration levels to below 4 pCi/l and to 2 pCi/L or below 70-80 percent of the time. The average radon level in homes is about 1.25 pCi/L. Although Congress passed legislation in 1988 establishing a national goal that indoor radon levels not exceed ambient outdoor radon levels (0.2-0.7 pCi/L), this goal is not yet technologically achievable.
Information provided above is from "A Physician's Guide"