Radon Testing Information

Testing Your Home or Office

The only way to know if you have a radon problem in your home or office is to test.

Pennsylvania law requires that persons, other than the owner, performing radon services (testing, mitigation, and/or laboratory analysis) be certified by the Department of Environmental Protection (DEP).
We recommend you verify certification.
Testing Devices
  • Short-term versus Long term

    • A short-term test remains in your home or office from two to 90 days, depending on the device. A long-term test remains in your home or office for more than 90 days.

    • Because radon levels tend to vary from day to day and season to season, a long-term test is more likely to tell you your year-round average radon level. A short-term test is the quickest way to screen your home for a potential radon problem.

  • Passive versus Active

    • Passive radon testing devices do not need power to function. They include charcoal canisters, alpha track detectors and charcoal liquid scintillation devices that are available in hardware stores, drug stores and by mail. Electret ion chambers are generally only available through certified testers or laboratories. Passive devices are exposed to the air in the home or office for a specified period of time and then sent to a certified laboratory for analysis.

    • Active radon testing devices require electrical or battery power to function. Continuous radon monitors and continuous working level monitors require operation by certified testers.

  • Radon Measurement Method Definitions (EPA)
    • Excerpted from U.S. EPA National Radon Proficiency Program Handbook, Appendix A: Radon Proficiency Program Measurement Method Definitions, pp 70-74, July 1996.

  • Indoor Radon and Radon Decay Product Measurement Device Protocols (EPA)
    • U.S. EPA, Office of Air and Radiation (6604J)
      EPA 402-R-92-004, July 1992
Where to Test

DEP recommends testing the lowest livable area of the building and considers the basement, if any, to be the lowest livable area if it can be used as a living area without major structural changes. For real estate transactions, this is true even if the basement is not currently renovated into a finished living space because the buyer may renovate and use the basement as a living space. Naturally, basements with ground floors or low ceilings would need major structural changes and, therefore, would not be considered the lowest livable area.

DEP recommends testing two or more locations, including the lowest livable, if the house has separate structural zones such as a family room above a crawl space or on a slab-on-grade.

Testing Protocols
  • Closed House Conditions

    • If a radon test is placed for less than four days, all doors and windows must be closed, except for normal entrance and exiting, and all fans and other external/internal ventilation systems, except the furnace, must not be operating for at least 12 hours prior to the test and during the entire testing period.

    • Short-term tests lasting less than four days should not be conducted during severe storms or periods of high winds.

  • Placement: All radon testing devices must be placed at least:

    • 20 inches off the floor,
    • 4 inches from other objects,
    • 1 foot from external walls,
    • 3 feet from windows or other potential openings in the exterior walls and
    • for at least 48 continuous hours.

  • Results

    • The Environmental Protection Agency (EPA) recommends that you take action to reduce you home indoor radon levels if your radon test is 4 pCi/L or higher.

    • If the test was not done as part of a real estate transaction, DEP's A Citizen's Guide to Radon is the best guide to interpret your results.

    • If the test was done as part of a real estate transaction, Pennsylvania's Home Buyer's and Seller's Guide to Radon is the best guide to interpret your results.

    • If your radon test result is greater than 100 pCi/L, DEP will provide free confirmatory testing.