When should I have my house tested for Radon?

You may use this test during any season, as long as closed building conditions can be maintained. All external doors, windows, and vents should be kept closed from 12 hours before starting the test until the end of the test, minimum of 48 hours. You don’t need to change your normal entry and exit routines, just make sure you close the door behind you. If the building has a permanently installed radon mitigation system, air to air heat exchanger, and/or combustion air supplies for furnaces, etc., they should be operated normally. However, do not operate any whole house or window fans during the test.