How do I test for radon?
Short-Term Tests - Radon Potential
Long-Term Tests - Actual Radon Exposure
Testing for Radon Decay Products
Key Points About Testing
What do test results mean?
How do I find a radon measurement contractor?
HOW DO I TEST FOR RADON?
Short-Term Test Devices Picture: US EPA
There are reliable ways to measure indoor radon for short-term test periods that last only a few days, and for long-term test periods that may range from a few months to more than a year. Using recommended measurement devices, you can determine the radon potential of the home under "worst case conditions" (short term test) or measure actual radon exposure under normal living conditions (long term test).
SHORT-TERM TESTS - RADON POTENTIAL
Often, at the time of resale, it is desirable to know what the potential radon exposures could be, independent of how the occupants use a building. Short-term tests typically are conducted over a two to seven day period. Results of short term tests represent the radon potential of the home, more than the actual average exposure to residents under normal living conditions, unless the residents keep the home's windows and doors closed year-round.
This is because EPA guidelines for short-term radon tests require "Closed-House Conditions" to promote maximum radon concentration during the brief test period.
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Short Term Test Devices
There are two types of short-term test devices:
- Integrating Devices, which measure radon in real time and provide an average reading over the time of the test; and
- Continuous Radon Monitors, which measure radon and provide hourly readings as well as an overall average.
It is not appropriate to use "Grab Samples," which test for less than 48 hours, as this is more of a diagnostic device and will not provide a representative radon potential measurement for the home.
If a short-term radon test is conducted correctly for a minimum of two days, under closed-house conditions, one can reasonably say:
- If the result is less than 4.0 pCi/L, the annual average of the home under normal lived-in conditions is also likely to be less than 4.0 pCi/L.
- If the level is at or above 4.0 pCi/L, the house has the potential to average more than 4.0 pCi/L, and you should consider follow-up testing or taking action to reduce (mitigate) the radon in the home
LONG-TERM TESTS MEASURE - ACTUAL RADON EXPOSURE
For the occupants of a home, actual radon exposure depends on how they use the home, where in the home the occupants spend their time, and how much fresh air is brought into the living area. Since these factors may vary over time, the only reliable way of measuring the actual radon exposure is to conduct a long-term test for a minimum of 91 days under normal living conditions.
In the past, prospective homeowners have often been reluctant to purchase a home before performing a long-term test for fear of not being able to correct a radon problem afterward. However, improved technology and the proven durability of radon mitigation systems have served to reduce much of that concern.
This does not mean that a short-term test is less valuable as part of a home inspection process, but rather, if the results of that test show a potential radon concern, a long-term test can more accurately show average radon levels. By conducting a long-term test after moving into a home, the homeowner can control test conditions and, if needed, make decisions on how the mitigation system will be installed.
The placement of the test device within the home must be in accordance with the manufacturer's instructions.
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TESTING FOR RADON DECAY PRODUCTS
Radon decay products can also be measured using a special monitor that reports in Working Levels (WL). This can be done as an initial measurement or, more typically, after initial measurements have identified a potential concern in commercial buildings or homes with relatively low initial radon readings. The EPA guidance for radon decay products (comparable to 4.0 pCi/L of radon) recommends that people should avoid long-term exposures in excess of 0.02 WL of radon decay products.
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KEY POINTS ABOUT TESTING
Homebuyers and sellers often prefer to have a radon test performed by a trained professional tester. In that case, EPA strongly recommends the use of a qualified radon measurement professional who has been trained in the proper placement of radon measurement devices and the interpretation of their results.
Here are some tips for testing and reducing radon:
- Radon tests are to be placed in livable areas - not crawlspaces or attics.
- Radon tests are to be placed no closer than 20 inches to the floor, and no closer than three feet from openings in exterior walls, such as windows and doors.
- Collecting data for less than 48 hours is not valid for determining the need to reduce radon in a home.
- When performing a short-term test of less than 90 days, all exterior doors and windows are to be closed other than for normal entry and exit; and the test device is to be placed in the lowest level of the home suitable for occupancy.
- When doing a long-term test of more than 90 days, no special conditions are required and the test device is typically placed in the lowest level of the home that is frequently occupied.
- Radon levels vary from season to season and long-term tests are the preferred method for determining health risk.
- For most homes, test devices need to be placed in only one room on the selected level of the home.
- If the radon measurement professional performs two short-term tests at the same location, under the same conditions, but at different times, the results should be averaged. It is not acceptable to continue to test until a preferred result is obtained.
- Radon test results obtained from different parts of the home are NOT averaged.
- During short-term tests, evaporative coolers (swamp coolers) and other devices that cause a significant exchange of outdoor air for indoor air should be shut-off, unless part of a bonafide radon mitigation system.
- Test devices should not be placed on hot surfaces, or in areas of elevated humidity.
- If a continuous monitor (which measures radon or radon decay products hourly) is utilized, the average of the measurements is used to determine the need for follow-up, rather than the highest observed reading.
- Continuous monitors are sometimes used to detect occupant tampering of test conditions.
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WHAT DO TEST RESULTS MEAN?
- There is no “totally safe” level of radon exposure.
- 4 picoCuries per liter is the “action level” recommended by the EPA
- All radon problems can be fixed
- Radon levels in homes can typically be reduced to between 2 - 4 picoCuries per liter.
HOW DO I FIND A RADON MEASUREMENT CONTRACTOR?
The Arizona Radiation Regulatory Agency (ARRA) does not regulate or certify radon testers or mitigation specialists.
Contractors are licensed and regulated in Arizona by the Arizona Registrar of Contractors (ROC). Radon testers or mitigation specialists may need to be licensed by the ROC. You can contact the ROC as follows:
Within Maricopa County: (602) 542-1525
Toll free: 1-877-MY AZROC (1-877-692-9762)
To find qualified radon contractors, EPA recommends that you contact one or both of the two privately-run national certification programs listed below. You can find a listing of certified individuals through their websites as follows:
National Environmental Health Association
National Radon Proficiency Program (NEHA NRPP)
Address: PO Box 2109, Fletcher, NC 28732
Phone: (800) 269-4174; (828) 890-4117
Fax: (828) 890-4161
National Radon Safety Board (NRSB)
Address: PO Box 703, Athens, TX 75751
Phone: (866) 329-3474
Fax: (903) 675-3748
In addition to asking about a radon contractor's training and credentials, homeowners should always:
- Ask for references;
- Require proof of certification, including agreement to follow protocols and codes of ethics;
- Ask for proof of insurance including workers' compensation; and
- Ask for a concise contract.