CHARCOAL TEST KITS
Charcoal kits are short term devices and if properly deployed can provide fairly accurate radon tests. However, there are several "weaknesses" of charcoal kits:
1) Upon their completion, they must be "mailed off" by the tester to a laboratory for processing AND analysis and interpretation.
2) They only provide a single "average" at the end of the test based on the total exposure (whereas good "continuous monitors" take hourly samples and let you see HOW the final result was obtained).
3) Charcoal kits are "biased" towards the last 12 hours or so of a test. If the test was deployed in the morning during a home inspection that means the last 12 hours would be into the "previous evening". Radon TENDS to be "higher" in the evenings so you dont know if "evening spikes" have "weighted" your test abnormally. With continuous monitors, you can SEE the hour by hour test data!
4) Charcoal kits are more susceptible to "tampering" which could directly impact final test results!
5) If you are concerned about "test integrity" you should NOT rely on charcoal tests for real estate transactions or to solely determine whether your home should be mitigated!