• Use a test device that frequently records radon or decay product levels to detect unusual swings;
  
  
• Employ a motion detector to determine whether the test device has been moved or testing conditions have changed;
  
  
• Use a proximity detector to reveal the presence of people in the room which may correlate to possible changes in radon levels during the test;
  
  
• Record the barometric pressure to identify weather conditions which may have affected the test;
  
  
• Record the temperature record to help assess whether doors and windows have been opened;
  
  
• Apply tamper-proof seals to windows to ensure closed house conditions; and
  
  
• Have the seller/occupant sign a non-interference agreement.

Home buyers and sellers should consult a qualified radon test provider about the use of these precautions.

Length of Time to Test
There are two general ways to test your home for radon - Because radon levels vary from day to day and season to season, a short-term test is less likely than a long-term test to tell you your year-round average radon level. However, if you need results quickly, a short-term test may be used to decide whether to fix the home.

1. Short-Term Testing - The quickest way to test is with short-term tests. Short-term tests remain in your home from two days to 90 days, depending on the device. There are two groups of devices which are more commonly used for short-term testing. The passive device group includes alpha track detectors, charcoal canisters, charcoal liquid scintillation detectors, and electret ion chambers. The active device group consists of different types of continuous monitors.
   
   Whether you test for radon yourself or hire a state-certified tester or a privately certified tester, all radon tests should be taken for a minimum of 48 hours. A longer period of testing is required for some devices.
   
   
2. Long-Term Testing - Long-term tests remain in your home for more than 90 days. Alpha track, and electret ion chamber detectors are commonly used for this type of testing. A long-term test will give you a reading that is more likely to tell you your home's year-round average radon level than a short-term test. If time permits (more than 90 days) long-term tests can be used to confirm initial short-term results. When long-term test results are 4 pCi/L or higher, EPA recommends fixing the home.