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Testing for Radon Gas

Several different measurement methods may be used to determine the radon concentrations in structures. Each method has its own advantages and disadvantages. Users must decide which method is best suited to their situation.

The Public Health Division recommends a method which will provide an annual average radon concentration in the living area of a structure.

Short-term tests last from 2-90 days whereas long-term tests last from 91 days to 1 year. Various other dynamic testing methods are also available but are generally much more expensive to use.

Performing a Radon Test Yourself

You can easily test your home yourself. The Environmental Protection Agency recommends the following:
Step 1. Take a short-term radon test. If your result is 4 pCi/L or higher, take a follow up test to be sure. 
Step 2.  Depending on the results of your first test, follow up with either a long-term test or a second short term test. If your short-term test results were 8 pCi/L or above, follow up with another short-term test. If your short-term test results are below 8 pCi/L follow up with a long-term test. Long-term tests will give you a more accurate reading of your year-round average radon level. 
Step 3.  If the average of your first two short-term tests is 4 pCi/L or above, or the result of your long-term test was 4 pCi/L or above, fix your home. 
If your test results are below the action level of 4 pCi/L, you may want to retest in two to five years. You 

To make sure your test results are accurate, here are important things to remember:

  • For short-term testing, close your home's windows and outside doors at least 12 hours before beginning test.
  • During the test, keep windows and outside doors shut except for normal entry & exit from the home. Your heating and cooling systems should be set appropriateley for the season. [Such "closed house" conditions are not required for long-term tests i.e. those that take 91 days or more.]
  • Do not conduct short-term tests during unusually severe storms or periods of unusually high winds.
  • Place kit at least 20 inches above floor in a location it won't be disturbed - away from drafts, high heat, high humidity and the home's exterior walls.
  • Leave the kit in place for as long as the package says.
  • When you've fnished the test, reseal the package it came in, and send it immediately to the test kit manufacturer's laboratory specified on the package. You may want to copy down the test kit's serial number and the company's customer service number. Why? If you don't get your test result back a few weeks after mailing it, you'll be able to call and find out about the status of "your" kit.

IMPORTANT: Most short-term kits come with the postage pre-paid. They are manufactured to be accurate as long as the make it back to the lab eight days after the test is stopped. A test processed after that point may give invalid results. If you know regular US Mail is slow in your area, we recommend you send it to the lab using 2-3 day "US Priority Mail" (or an "overnight" service like Fedex).

What Your Test Results MeanDrawing of lungs

Radon is measures in picocuries per liter (pCi/L). The EPA's "action level" of 4.0 pCi/L, where it  strongly advises that a home be fixed, is not a health-based standard. There is no “safe level” of radon exposure; any radon exposure carries some risk. Even radon levels below 4.0 pCi/L pose some risk. You can reduce your risk of lung cancer by lowering your radon level. See What are the health risks associated with radon? for more information on those risks.

The EPA has estimated that the average indoor radon level in the U.S. is 1.3 pCi/L. The average radon concentration in the outdoor air in the U.S. has been estimated to be about 0.4 pCi/L. Congress has set a long-term goal that indoor radon levels be no more than outdoor levels. While this goal is not technologically achievable in all cases, most homes can be reduced to 2 pCi/L or below. 

Radon Measurement & Mitigation Companies

Radon Measurement Companies (download as a pdf)
Radon Mitigation Companies (download as a pdf)