What is a radon test?

A radon test measures the levels of radon gas — an odorless radioactive gas — due to uranium breaking down within soil and water found present in the home. Radon gas seeps into the home through cracks in the foundation and contaminates the indoor air in your home. Inspectors can test the air inside your home using specialized devices that can detect and measure radon gas concentrations in a building. If radon levels are high, you can perform repairs and interventions to reduce those levels.

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Why do I need a radon test when buying a house?

Your house needs to be tested for radon because research has linked prolonged exposure to radon gas in homes to significant health problems such as lung cancer. You want to ensure that the home you're making an offer on is in a good, safe, livable condition.

According to the EPA and the Surgeon General's office, radon exposure is responsible for more than 21,000 lung cancer deaths yearly in the United States. The radioactive particles can get trapped in your lungs when you breathe in radon.

Radon levels vary throughout different regions of the country and can even vary throughout individual neighborhoods. National Radon Defense has a heat map showing the areas where radon levels could be higher.

Pro tip:

Given that you cannot see, smell, or taste the presence of radon gas, it's essential to test your home to detect its presence.

What is the home radon test process?

The two major categories of radon testing devices are passive and active:

  • Passive radon testing devices include charcoal canisters, which absorb radon. After the test period, the inspector sends the device to a laboratory for analysis to determine the radon levels. DIY radon testing kits are typically passive tests.
  • Active radon testing devices are electronic, continuous monitoring devices that provide real-time measurements of the concentration of radon gas. An active device gives immediate results, and you'll see how radon levels fluctuate over time.

When deciding how to test a home for radon, you have two options:

  1. Hire a qualified radon tester

    A qualified inspector will have passed a state-run radon program or completed courses via the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). Contact your state's local radon programs to find qualified professionals in your area.

    The inspector will place the testing devices in various locations in the home, but typically in the lowest, livable space. With a passive test, the devices go to a lab for analysis. You can monitor active tests in real time. When the test is complete, you'll receive a report about the radon levels in your home. The EPA (Environmental Protection Agency) recommends enlisting the help of a professional radon tester.

  2. Use a DIY radon testing kit

    Contact your state's radon program for information about DIY home radon testing kits and where to obtain them. The EPA has information about radon specific to your local area. Follow the kit's directions closely, as any deviation could result in inaccurate readings. The two types of DIY kits are short-term and long-term. Short-term kits will test your radon levels over 2-90 days. A long-term kit will test levels over more than 90 days.

    The CDC recommends a long-term test (over 90 days) because the more data you obtain, the more accurate your results will be. The process generally involves placing a measuring device in the basement or lowest level of your home, three feet off the floor.

    Should I get a radon test with home inspection?

    When a buyer is considering purchasing a home, they will typically hire a home inspector to conduct a thorough home inspection to ensure it's structurally sound, all the systems are working properly, and it's safe to live in. Testing for the presence of radon is part of the health and safety aspect of a home inspection. Your home inspector can also inspect a radon mitigation system already present in the home to ensure it's functioning properly and reducing radon levels.

    Is a radon home inspection required to sell a home?

    You might wonder, is radon testing necessary? While no federal mandates exist with specific radon requirements, certain states may require a radon test before selling a home. The EPA has set guidelines and recommends that you address a radon reading of 4 pCi/L (picocuries per liter) or greater with repairs and further inspections. A pCi is a measure of the rate of radioactive decay of radon. The CDC has information about what to do should a radon test show high levels (at or above 4 pCi/L).

    A real estate transaction is a common opportunity for a house to get tested for radon. The Minnesota Department of Health (MDH) noticed that in a recent, fast-paced real estate market, when fewer buyers were getting home inspections, the number of home radon tests declined by 39%, meaning fewer home buyers were identifying the cancer-causing hazard lurking in their prospective homes.

    When should you test for radon?

    The seller should share the results with you if they have tested the home for radon recently. If they have not— or if the test results are more than two years old — you can request another test. It's not always required, but knowing potential health hazards is crucial when buying a home. The EPA has a guide for home buyers and sellers about radon. Learn more about what to look for when buying a house.

    There are several points where a radon inspection makes sense, including:

    • Before buying a home so you can be aware of current radon levels and whether they require mitigation
    • Home renovation projects might include a radon test, especially if you will be modifying the basement or lower levels of the home
    • Periodically. If your home hasn't had a radon test in the past two to five years, you might consider getting it tested
    • Your neighbor's high radon test results could mean that your home might also have elevated radon levels
    • After you've installed a radon mitigation system, you might run a test to measure its effectiveness

    Radon testing helps ensure the safety of your home for you and your family. The Centers for Disease Control and Prevention has information about radon house testing. Always follow the guidelines of your local authorities and public health organizations for radon testing and mitigation.

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