Home Inspection

How Does a Radon Test Work: Radon Gas Testing Processes

Radon tests work by measuring the levels of radon gas in a home or business. These tests typically involve:

  1. Placing a collection device or kit in the lowest area for a specific period of time.
  2. The device or kit then collects air samples to determine the concentration of radon gas present.
  3. The test results can help determine if any mitigation measures are necessary to reduce radon levels and ensure a safe living or working environment.

Radon exposure is the second leading cause of lung cancer after smoking, it’s crucial to understand how to check for and address radon in your living environment.

Radon testing can identify the presence and concentration of radon gas within your home. Radon tests fall into two major categories: short-term and long-term tests.

How Does A Radon Test Work

1. Choosing a Test Kit

There are two primary types of radon test kits: short-term and long-term.

Short-term tests are typically used for initial screenings. They can take from a few days to 90 days, while long-term tests measure radon levels for over 90 days, providing a more accurate assessment of the average radon concentration over time.

Short-term Radon Tests

Short-term tests are used when quick results are needed. They are less accurate than long-term tests because radon levels vary significantly daily and by season. These measure radon levels for 2 to 7 days. They are helpful if quick results are needed but are less accurate than long-term tests.

Charcoal Canisters

  • Description: Small canisters filled with activated charcoal. Radon and its decay products adhere to the charcoal.
  • Duration: 2 to 7 days.
  • Pros: Inexpensive, easy to use.
  • Cons: Less accurate, can be affected by humidity.

Alpha Track Detectors

  • Description: A piece of plastic or film inside a small container. When radon decay particles strike the detector, they cause damage to tracks.
  • Duration: 2 to 7 days.
  • Pros: It is not affected by humidity and is more accurate than charcoal canisters.
  • Cons: Requires analysis by a lab.

Electret Ion Chambers

  • Description: Uses an electrostatically charged disk to measure radon and its decay products.
  • Duration: 2 to 7 days.
  • Pros: Can be read immediately after the test period.
  • Cons: More expensive, requires special equipment to read the results.

Continuous Radon Monitors

  • Description: Electronic devices that provide continuous measurements of radon levels.
  • Duration: 2 to 7 days.
  • Pros: Provides a detailed record of radon levels and can detect unusual or abnormal readings.
  • Cons: More expensive, usually used by professionals.

Long-term Radon Tests

Long-term tests measure radon levels for more than 90 days and are considered more accurate as they account for fluctuations in radon levels over different seasons. These measure radon levels for 90 days to one year. While they take longer, they provide a better understanding of the average radon level over time.

Alpha Track Detectors

  • Description: Similar to the short-term version but used over a longer period.
  • Duration: 90 days to one year.
  • Pros: Provides a more accurate representation of the annual average radon level.
  • Cons: Results are not immediate; they require analysis by a lab.

Electret Ion Chambers

  • Description: Similar to the short-term version but used over a longer period.
  • Duration: 90 days to one year.
  • Pros: Can be more accurate over long periods.
  • Cons: More expensive, requires special equipment to read the results.

Professional radon tests conducted by certified radon technicians or DIY home test kits available at hardware stores can assess radon levels.

Digital Radon Monitors

Radon monitors are technically advanced devices that can be used for both short-term and long-term testing. They provide continuous monitoring and display the radon level. Some models can connect to smartphones or other devices to provide real-time data and alerts.

These electric monitors can detect and record radon levels over extended periods and provide detailed data on fluctuations, making them an invaluable tool for constant monitoring of your indoor air quality.

Though more expensive than other testing methods, these devices give the immediate benefit of not waiting for lab results and allow you to take timely action in the case of high radon readings, potentially leading to prompt radon mitigation steps.

2. Placement of the Test Kit

  • The test kit is usually placed in the lowest lived-in level of the home where people spend time, like a basement or a ground-floor room.
  • It should be removed from drafts, high heat, high humidity, and exterior walls.
  • The kit should be placed at least 20 inches above the floor.

Preparing for Radon Testing

Before you begin testing for radon, ensure your home is ready for the test to guarantee accurate results. You will need to:

  • Close all windows and doors at least 12 hours before starting the test.
  • Avoid placing the radon detector in areas of high humidity or direct sunlight, such as bathrooms or sunrooms.
  • Maintain normal home ventilation without using fans or other machines that bring in air from outside.

The radon test should be placed in the lowest level of your home where you spend time, like the basement or a ground-floor room.

3. Conducting a Radon Test

Conducting a radon test is crucial in assessing whether your home has high radon levels. Your careful attention to preparation, execution, and interpretation of test results determines the accuracy of the reading, which can be vital for your health and safety.

  • Windows and doors should be kept closed as much as possible during the test.
  • Avoid placing the kit in areas of high humidity, like bathrooms or kitchens.
  • Devices that bring in air from outside, like ventilation fans or air purifiers, should not be used during testing.

4. After the Test

After the testing period, send the device to a laboratory, typically using pre-addressed mail provided with the test kit, or if using a digital detector, download the results according to manufacturer directions.

  • Once the testing period ends, the kit is sealed and sent to a laboratory for analysis.
  • The lab measures the amount of radon or its decay products in the device and calculates the radon level in the air during the testing period.

5. Understanding the Results

When you receive your test results:

  • Understand that the EPA action level for radon is 4 picocuries per liter (pCi/L). Further action is recommended if your test results show radon levels at or above this threshold.
  • Consider retesting if the results are close to 4 pCi/L to confirm whether mitigation is necessary. The US Environmental Protection Agency (EPA) recommends taking action to reduce radon levels if the result is 4 pCi/L or higher.
  • For high radon levels, it’s advisable to consult with a radon mitigation professional to discuss steps to reduce radon in your home effectively.

Remember that accuracy in radon testing is essential for your health; hence, follow each step diligently and seek professional advice if necessary.

6. Follow-up Testing

If initial short-term test results are high, a follow-up test is recommended to confirm the results.

If levels are still high, it’s advisable to consult a radon mitigation professional to discuss ways to reduce radon levels in the home.

7. Radon Mitigation

If high radon levels are confirmed, radon mitigation systems can be installed. These systems can significantly reduce radon levels in your home. Common methods include soil suction, which draws radon from beneath the house and vents it outside, and improving the ventilation in the house.

Using a radon test kit that meets the EPA’s requirements or is state-certified is important. Some states offer residents free or discounted test kits, and hardware stores sell them.

Radon Mitigation Fan

Professional Radon Reduction Systems

Hiring a licensed professional is often the most reliable way to reduce radon levels in your home.

Professional radon reduction systems typically consist of a vent pipe system and a radon fan, which work together to pull radon from beneath the building and vent it outside. Sealing gaps in walls and floors with caulk prevents radon from entering.

Professionals may also incorporate radon-resistant construction techniques in new builds, such as installing physical barriers and vent pipes during construction.

DIY Approaches to Reduce Radon Levels

For a hands-on homeowner, DIY approaches can be considered to reduce radon. Simple methods include sealing cracks in the foundation with caulk and using activated carbon filter systems to reduce airborne radon.

More complex techniques should be approached cautiously, like creating suction with a sump pump system. Remember that radon levels can fluctuate, so continuous monitoring is imperative. Always consult a professional before attempting significant modifications to ensure safety and effectiveness.

Maintaining Reduced Radon Levels

After implementing a radon reduction system, it’s important to maintain it to ensure that reduced radon levels remain low. This includes regular inspections of system components such as the vent pipe and radon fan.

Continuous radon tests are recommended to monitor levels over time. Observing operation indicators and maintaining building and construction joints that are effectively sealed will help ensure that your mitigation system functions appropriately.

Understanding Radon Gas

Before you conduct a radon test, it’s important to grasp what radon is, the health implications it may carry, and its common sources in your home.

Radon Characteristics

Radon is a radioactive gas that is both odorless and colorless, making its presence undetectable without specialized testing tools. It arises from the natural decay of uranium, which can be found in nearly all soils and rocks.

Because of its gaseous state, radon can move freely through the soil, enabling it to enter homes through cracks and foundation gaps.

Health Risks Associated with Radon

Exposure to radon leads to inhaling radioactive particles that can damage the cells lining your lungs.

The Environmental Protection Agency (EPA) identifies radon as the second leading cause of lung cancer in the US after smoking. Even at low levels, long-term radon exposure can increase the risk of lung cancer.

Sources of Radon in Homes

Radon typically enters homes through:

  • Cracks in slab foundations or concrete basement floors and walls
  • Construction joints
  • Gaps in suspended floors, particularly above crawl spaces
  • Gaps around service pipes and other wall penetrations

Basements and crawl spaces allow for the highest potential radon concentration due to their proximity to the ground where radon emanates. Radon levels can vary significantly from home to home, and the only way to know your home’s radon level is to test.

How Radon Gas Enters A House

The Importance of Radon Testing

Radon testing is critical for ensuring your home is within safe radon levels, measured in picocuries per liter (pci/L). Understanding and managing radon exposure reduces your risk of lung cancer caused by this odorless and tasteless gas.

Radon Levels and Safety Thresholds

The Environmental Protection Agency (EPA) identifies the action level for radon at 4 picocuries per liter (pci/L). This is the threshold at which you are advised to take measures to reduce radon levels in your home. Keeping indoor radon below this level reduces the risk of health issues associated with long-term exposure.

Risk Factors for Radon Exposure

Your risk of radon exposure depends on several factors, such as the geographic location of your home and its construction. High radon levels can be found in all fifty states and homes of any type. It is essential to test your home, as radon has been identified as the second leading cause of lung cancer.

Long-Term vs. Short-Term Radon Testing

Short-term tests are quick ways to screen your home for radon, typically from a few days to 90 days. For a more accurate assessment, long-term tests last more than 90 days and better indicate average year-round radon levels. It’s crucial to use the correct radon test for your situation to ensure the safety of your living environment.

Legal and Real Estate Considerations

Understanding the legal implications and real estate procedures surrounding radon testing is crucial when buying or selling a property. Radon’s health risks make it a significant factor in real estate transactions.

Disclosure and Regulations

Disclosure: When selling your home, several states require you to disclose known radon levels, mainly if you’ve previously conducted an EPA-approved radon test. Failure to disclose can lead to legal liabilities.

  • Regulations: The Environmental Protection Agency (EPA) provides guidelines for radon levels, recommending mitigation for higher radon levels exceeding 4 pCi/L. While these are not enforceable laws, they influence state and local regulations.

Buying and Selling Property with Radon Concerns

Buying: Before committing to buying a new home, requesting or conducting a long-term radon test is wise. This will ensure your future home has lower radon levels or that you are prepared to discuss mitigation if necessary.

  • Selling: If you’re preparing to sell your house and have not had a radon test recently, engaging qualified radon testers can be a proactive step. This can be part of a broader home inspection process and provide potential buyers peace of mind.

Remember that renovations can influence radon levels by changing how radon enters or is distributed throughout your home. Always test your home after significant changes to its structure.

Support and Resources

Access to reliable support and resources is essential for ensuring accuracy and safety when dealing with radon testing. Your state radon office, the Environmental Protection Agency (EPA), and professional radon mitigation experts offer a wealth of knowledge to assist you through the process.

Contacting State Radon Offices

Your state radon office is a valuable resource for obtaining radon test kits and information specific to your region. These offices provide detailed guidance on testing procedures and what to do if your levels are elevated.

To find your state’s radon office, visit the EPA’s list of regional radon contacts and select your state for targeted assistance.

Utilizing Environmental Protection Agency Resources

The Environmental Protection Agency (EPA) offers extensive resources to educate you about the health risks associated with radon.

They provide a comprehensive range of materials, including publications on conducting a radon test and the steps for radon mitigation. Exploring the EPA’s radon guide is highly recommended for more detailed information.

Professional Support for Radon Issues

If radon testing uncovers levels above EPA recommended limits, seeking professional support is crucial. Qualified radon mitigation professionals have the expertise to advise and implement the most effective measures to reduce radon levels safely in your home.

It is recommended to consult nationwide databases such as the one provided by the National Radon Safety Board or the ‘contact us’ sections on professional mitigation websites to find certified experts near you.

Frequently Asked Questions

Understanding the process and necessary precautions for radon testing is critical to ensuring the accuracy and reliability of your results. These FAQs address the specifics of conducting a radon test in your home.

Is it OK to live in a house with radon?

Living in a house with radon can be safe as long as the radon levels are within the acceptable range or you have a radon mitigation system to reduce high radon levels to minimize health risks.

What is the proper duration for conducting a radon test on a house?

A short-term radon test typically lasts 2 to 90 days, while a long-term test extends beyond 90 days. A short-term test is appropriate for a snapshot of your radon levels; however, long-term tests provide a more accurate assessment of average radon exposure.

How should a radon detection device be positioned within a home for accurate measurement?

Place the radon detection device in the lowest lived-in level of your home where it won’t be disturbed. It should be at least 20 inches above the floor, away from drafts, high heat, humidity, and exterior walls.

Are there specific actions to avoid to ensure the integrity of a radon test?

During a radon test, avoid moving or covering the test device, opening windows, or operating fans that bring in air from outside because these actions can affect test results.

What steps are involved in testing a home for radon presence?

First, choose the type of radon test kit you intend to use. Next, place the device according to the instructions. Once the test duration is complete, send the device to a laboratory for analysis.

What precautions should be taken to prepare a home before initiating a radon test?

Ensure all windows and doors are closed (except for normal entry and exit) for 12 hours before and during testing. Maintain regular heating or cooling patterns and avoid fans that circulate outdoor air.

Is it safe to occupy a home while a radon-level assessment is being conducted?

Yes, it is safe to remain in your home while a radon test is being conducted, as the devices used for testing do not emit any substances, and radon testing is non-invasive.


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.