Getting Tested: Home Radon Detectors

Am I being exposed?

Where can I get a radon detector to test my home?

What kinds of  radon tests are best?

What tests should I do if I am:

selling a house?

buying a house?

How does radon change over time in a house?


What are short-term tests good for?

Should I test my water supply for radon?

Are tests available for materials or surveys?

The text on this page is designed to inform you about radon testing in your home or workplace  To skip ahead to decide what kind of test to do  click here ; to order a detector kit click here

Am I being exposed to dangerous levels of radiation from the radon in my home or workplace?
That's the question that leads most people to think about testing their home or workplace for radon. There are many buildings where long-term exposure to radon-related radiation can be a serious health hazard. Most radon experts and radiation protection specialists believe that if you are constantly being exposed at concentrations of approximately 4 pCi/L or more, then you are at risk. The only way to know for sure your radon exposure is to test the radon levels in the spaces where you spend time. Make sure that you do tests that give you information that is accurate enough to make a good decision.

What kinds of radon tests are best?
You will need to do a long-term test to get a measurement that will help you decide if it is worthwhile to take action to reduce your radon exposure. By long-term, we mean 90 days or more. The 90 days should span a strong seasonal change when your house goes from closed conditions (continuous heating or cooling) to open or natural ventilation conditions. It is best if the test lasts for a year. Unfortunately, most of the radon tests being done today are short term, lasting only 2 to 7 days. That is too short a time to reliably estimate the average radon concentration over the typical time most people reside in their home because radon gas levels can vary tremendously from day-to-day and season to season. That means if you happen to measure during a short period when the radon is unusually high or low, you may be seriously misled. Follow this link to help you plan the kind of radon test suited to your specific purpose.

How does radon change over time in a house?
Take a look at how the radon concentration varies in my house. (Temporal indoor radon changes).  My house is not unusual in its radon variation. Radon also varies within the building, so it is important to measure the long-term average radon concentration in your lived-in spaces.   If you only are making a single measurement in a house be aware that in most houses the radon concentration is highest in those rooms that are poorly ventilated and are close to, or surrounded by,  the ground.

Where can you get an inexpensive detector for a long-term radon measurement in my home?
Alpha track detectors (ATDs) are the best choice for your first long-term radon measurements.   ATDs are available online; RSSI, Accustar and Landauer make acceptable ATDs.  

What  short-term tests good for?
Short-term or screening measurements are fine if you want to quickly find out if your homes has extremely high radon. But short-term measurements don't accurately predict the health hazards associated with a lifetime's exposure to radon decay products.    If you are worried that your radon is so high that a year is too long to wait, combine a year long measurement with a 30 day screening measurement.  Follow this link for a more detailed response.

What kind of test do you recommend  if you are selling  your house?
Start a long-term test using an alpha track detector as soon as you decide that you might sell your house. The whole selling process is likely to take more than a month, so you can start a towards a long-term measurement. The longer you have the detector in place, the better the measurement. If you get an interested buyer who asks for a radon test, you can send the detector back to the lab when the buyer makes a serious offer and have the results within a week. Please note that some states or cities may have specific rules for real-estate transactions.  You should check with your state's radon contact. Follow this link for a more detailed response.

What kind of test do you recommend  if you are buying a house?
Ask for the results of a test that lasted for more than a few days. If no test has been done,  ask the seller to allow a 7 day to one month test. If only a 2 day test was done, ask for a second  test under closed house conditions. This second test could consist of a week-long test for a rapid screening for extremely high radon, and an alpha track test whose results could be used to access mitigation funds in an escrow account post-sale. If you must take a 2 day test, I prefer an EPERM device because it is less likely to fail than one based on charcoal canister.  Please note that some states or cities may have specific rules for real-estate transactions.   You should check with your state's radon contact. Follow this link for a more detailed response.

Should I test my water supply for radon?
Test your air first. If you find high radon, you may want to test your water if your water comes from wells. Surface water does not contain high radon concentrations. Water is not a major source for radon exposure in most homes.

Testing of materials and surveys?
For those interested in more exotic tests we can: measure the radon potential of source materials like water, soil, rock, and building materials; get an immediate picture of the radon levels in a neighborhood or town using grab samplers; test radon reduction systems by monitoring (almost instantaneously) changes in radon concentrations; measure the radon concentrations outside your home. Call 800-820-3209 to discuss your needs and interests.


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Questions/Comments, e-mail: Dr. Steck

Last revised : 22 February, 2013 

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