The EPA recommends that all houses be tested for radon. Montgomery county, the area I serve, has been identified by the EPA as an area with a higher potential for elevated radon levels. This is true of much of south eastern Pennsylvania. See EPA Map of Radon Zones for Pennsylvania.
I use a continuous radon monitor (CRM) it takes hour by hour measurement. Additionally, there are anti-tampering devices built in to it. If your house is being tested for radon, all exterior doors and windows (not just the basement) must be closed for 12 hours before the test begins and during the test. You can enter and exit and run the heat of air-conditioning, but you should not run exhaust fans.
Radon: The Health Hazard with a Simple Solution
Radon is a cancer-causing natural radioactive gas that you can’t see, smell or taste. Its presence in your home can pose a danger to your family’s health. Radon is the leading cause of lung cancer among non-smokers. Radon is the second leading cause of lung cancer in America and claims about 20,000 lives annually. Learn how you can protect your family.
Have Spotlight Home Inspection Test Your Home for Radon… it’s easy and inexpensive. Fix your home if you have a radon level of 4 pCi/L or more.
Additional Information on Radon