Radon Gas: Detection and Testing

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Home Improvement

How is Radon Detected?

Radon is a colorless and odorless gas that poses a significant health risk. Therefore, it is important to test homes for radon. According to the U.S. Office of the Surgeon General and U.S. EPA, all homes should be tested for radon especially during buying, selling, or building. Testing can be done by professionals or homeowners using an EPA-approved “do-it-yourself” kit.

Radon levels can vary with time and season, so testing can be done for short-term (two to 90 days) or long-term (more than three months). Short-term tests are best if results are needed quickly, followed by another short-term test. Long-term tests provide better information on a home’s average radon levels throughout the year. Radon testing devices are placed in the lowest level of the home that is occupied.

Types of Radon Test Devices

Radon tests measure either radon gas directly or the daughter products of radon’s radioactive decay. There are two categories of radon test devices: passive and active. Passive devices do not require electrical power and trap radon or its daughter products for later analysis in a laboratory. Passive devices include charcoal canisters, charcoal liquid scintillation detectors, alpha track detectors, and electret ion detectors.

  • Charcoal canisters and charcoal liquid scintillation detectors absorb radon or its products onto the charcoal. In the laboratory, the radioactive particles emitted from the charcoal are counted by a sodium iodide counter or converted to light in a liquid scintillation medium and counted in a scintillation detector.
  • Alpha track detectors have a plastic film that is etched by alpha particles that strike it. In the laboratory, the plastic is chemically treated to make the tracks visible, and then the tracks are counted.
  • Electret ion detectors have a statically charged Teflon disc. When an ion generated from radon decay strikes the Teflon disc, the electrical charge is reduced. In the laboratory, the charge reduction is measured, and the radon level is calculated.

Passive devices, except electret ion detectors, are available in hardware stores or by mail. Electret ion detectors are usually available through laboratories. Passive devices are generally less expensive and may require little or no special training. Of the passive devices, the charcoal canisters and charcoal liquid scintillation detectors are typically used for short-term tests.

Active devices need electrical power and include continuous monitoring devices like continuous radon monitors and continuous working level monitors. Active devices detect and record radon or its daughter products continuously. They are generally more expensive and require professionally trained testers for operation.

The average home has radon levels of about 1.25 picocuries per liter of air (pCi/L). If a radon test shows levels of 4 pCi/L or greater, then action must be taken to reduce the radon level. Radon can be reduced by preventing its entry into the home or by removing it once it has entered the home. Active ventilation in the basement or below the slab of the home is a common solution.


1. What is radon?

Radon is a colorless and odorless gas that is naturally present in the environment. It is formed by the decay of uranium in soil, rocks, and water.

2. How does radon get into homes?

Radon can seep into homes through cracks in the foundation, walls, and floors. It can also enter through gaps in pipes, drains, and other openings in the building.

3. What are the health risks of radon exposure?

Radon exposure can increase the risk of lung cancer, especially in smokers and those with a history of lung disease. Prolonged exposure to high levels of radon can also lead to other respiratory problems.

4. How can I test for radon in my home?

You can purchase a radon testing kit from a hardware store or online. The kit will include instructions on how to use it and where to send it for analysis. You can also hire a professional to test for radon in your home.

5. What is a safe level of radon in my home?

The US Environmental Protection Agency recommends that homes should have a radon level of 4 picocuries per liter (pCi/L) or lower. However, it is important to note that no level of radon exposure is completely safe.

6. How can I reduce radon levels in my home?

You can reduce radon levels in your home by sealing cracks and gaps in the foundation, walls, and floors. You can also install a radon mitigation system, which will vent radon gas from the soil beneath your home to the outside.

7. How often should I test for radon in my home?

The US Environmental Protection Agency recommends testing for radon every two years, or more frequently if you have made structural changes to your home or if there has been a significant seismic event in your area.

8. Is radon a problem in all areas?

Radon can be a problem in any area, but it is more common in certain regions, such as the Midwest and Northeast of the United States. It is important to test for radon regardless of where you live.

9. How does radon affect children?

Children are more susceptible to the harmful effects of radon exposure, as their lungs are still developing. Radon exposure in children can increase the risk of respiratory problems and lung cancer later in life.

10. Can radon be found in drinking water?

Radon can be present in well water, but it is not typically a problem in public water supplies. If you have a private well, it is recommended to test for radon in both air and water.

11. Are there any regulations for radon in homes?

There are no federal regulations for radon in homes, but some states and localities have their own regulations. It is important to check with your state or local health department for any regulations or guidelines.

12. What should I do if my home has high levels of radon?

If your home has high levels of radon, it is important to take steps to reduce the levels. You should contact a professional radon mitigation contractor to install a system to reduce the levels of radon in your home.

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