This is done with the charcoal activated canister method. The canister is about 4 inches in diameter and 1 inch high. The radioactive material in the air adheres to the charcoal. The canister must be exposed for a minimum of 48 hours (and ideally not more than 96 hours), after which it is analyzed by an EPA approved laboratory. The laboratory. analysis should be done as quickly as possible after the end of the test period, because of the short half-life of the radioactive material. For this reason, the canister should be returned to HRSS promptly after the test period.
Because this test covers a period of only a few days, there is a limit to its accuracy in reflecting an annual exposure average. If the reading is low, there probably is little likelihood that there is a radon problem. If the reading is slightly above the minimum, then a homeowner might want to do seasonal testing or perform a long-term test. If the reading is very high, you may have a serious problem. See Section About Exposure levels
HRSS delivers all canisters to the EPA-approved laboratory within one business day of receipt in Albuquerque. HRSS normally receives the laboratory results on the next business day after delivery to the laboratory. HRSS e-mails the results to its customer the same day as received from the laboratory, and then mails the original laboroatory report to its customer.
Long-term testing is known as an Alpha Track test. The minimum exposure period is 90 days, and the maximum exposure period is one year. Because this test covers a longer period of time than the charoal activated canister method, it more accurately reflects an average exposure.