Read the full document. From the At A Glance fact sheet:
EPA does not perform oversight of radon testing device accuracy or reliability. The 1988 Indoor Radon Abatement Act required that EPA establish proficiency programs for firms offering radon-related services, including testing and mitigation. EPA established and operated proficiency programs until 1998, when it disinvested in these programs. According to Agency representatives, EPA has neither the authority nor resources to ensure radon testing devices and testing laboratories are accurate and reliable. EPA asserts that it shares oversight responsibility with States and industry, including the two national proficiency programs operating under private auspices. However, without oversight, EPA cannot assure that radon testing devices provide accurate data on indoor radon risks or that radon testing laboratories accurately analyze and report radon results.
Recent studies – while not nationwide in scope – have identified problems with the accuracy of radon testing devices. Also, a recent New England study identified problems with the quality of laboratory analyses of radon testing. Nonetheless, a key 2009 EPA publication on the Agency’s Website continues to state that radon testing devices provide reliable measurements of indoor radon levels. In its 2009 A Citizen’s Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon, EPA states:
MYTH: Radon testing devices are not reliable and are difficult to find.
FACT: Reliable testing devices are available from qualified radon testers and companies.
However, EPA does not have data within the last 10 years to support that radon test kits or testers are reliable.