What is a long-term radon test?
Short-term radon tests are generally 2 to 7 days in length. Short-term tests must be made with closed house conditions. A long-term radon test is three months to one year in length. Long-term tests do not require closed house conditions. If radon measurements during a real estate transaction are questionable, a long-term test is sometimes performed with money left in an escrow account to pay for a radon mitigation system if the long-term test results are above the 4.0 pCi/L guideline.
