How do professionals test for radon?

Radon professionals generally use the same devices as available to home-testers. However, professionals have training and experience on where to place detectors, how long to leave them to measure radon concentration correctly, and the proper interpretation of test results. A professional may be able to characterize changes in radon concentration due to fluctuating weather changes and to identify tampering with a test device. Some radon professionals may also use devices that give continuous (realtime) measurements, to identify entry points.

Are contractors certified to address radon?

California law requires all individuals providing radon services to be certified by either the National Radon Safety Board (NRSB) or the National Environmental Health Association (NEHA).¹ No professional groups currently are exempted from this requirement, neither Industrial Hygienists (IHs), Registered Environmental Assessors (REAs), nor licensed or professional geologists.

The California Radon Program maintains lists of currently certified radon testers, mitigators, and laboratories.  Contact CDPH's Indoor Radon Program if you feel the service you received was not in accordance with applicable mitigation or testing standards.  Someone there will help you file a formal complaint with the NRSB or the NEHA.

Does the size of the problem matter?

The cost of radon reduction depends on the size and design of the building and the radon reduction methods that are needed. The EPA and the National Cancer Institute estimate that these costs typically range from $800 to $2,500, with an average cost of $1,200 for a home.

Is there guidance on hiring a contractor to fix radon?

If you are having a radon system installed you should look at the Radon Mitigation Standards so that you will know what you are supposed to be receiving and whether the system was installed correctly.