How to Test Your Home for Radon

Radon is a naturally occurring radioactive gas that enters homes silently through soil and rock beneath foundations. Because radon is colorless, odorless, and tasteless, testing is the only way to determine whether a home has elevated levels. Health agencies worldwide agree that every home should be tested regardless of location, construction type, or age. Understanding how radon testing works and which method to choose is essential for making informed decisions about indoor air safety.

Radon testing methods fall into two primary categories: short term tests and long term tests. Each approach measures radon differently and serves a distinct purpose. Selecting the correct method depends on whether the goal is initial screening, confirmation, or long range exposure assessment.

How Radon Enters the Home

Radon originates from the natural decay of uranium present in soil, rock, and groundwater. As uranium breaks down, radon gas forms and migrates upward through pore spaces in the ground. Homes create a pressure differential that draws soil gases inside through cracks in foundations, slab joints, sump pits, crawlspaces, and utility penetrations. Once indoors, radon can accumulate to hazardous levels, particularly in lower living areas such as basements and ground floors.

Because soil composition, moisture, building design, ventilation, and weather all influence radon movement, levels can vary significantly between neighboring homes. This variability makes regional assumptions unreliable and reinforces the importance of individual testing.

What Radon Tests Measure

Radon tests measure the concentration of radon gas in indoor air, typically expressed in picocuries per liter. A picocurie represents the radioactive decay rate, which correlates to potential radiation exposure in lung tissue when radon is inhaled. Long term exposure to elevated radon increases the risk of lung cancer, particularly for children and non smokers.

Testing devices do not measure uranium or radiation directly. Instead, they capture radon gas or its decay products over a defined period and calculate an average concentration based on exposure time.

Short Term Radon Testing Methods

Short term radon tests are designed to provide a quick snapshot of radon levels over a brief period. These tests typically remain in place for two to seven days and are commonly used as an initial screening tool.

Short term tests include charcoal canisters, charcoal liquid scintillation vials, electret ion chambers, and continuous radon monitors. Most consumer home test kits rely on charcoal adsorption because it is reliable, cost effective, and scientifically validated.

Charcoal based tests work by allowing radon gas to diffuse into a container where it is adsorbed onto activated charcoal. After the exposure period, the device is sealed and analyzed, either by laboratory measurement or internal colorimetric indicators depending on the design.

Short term testing is useful for identifying whether radon may be present at elevated levels, but results can be influenced by short term fluctuations caused by weather changes, ventilation patterns, or temporary pressure differences in the home. For this reason, short term results near or above action levels often require confirmation.

Short term tests should be conducted under closed house conditions. Windows and exterior doors should remain closed except for normal entry and exit. Testing should occur in the lowest lived in level of the home, such as a finished basement or first floor, and away from drafts, direct sunlight, and high humidity sources.

Long Term Radon Testing Methods

Long term radon tests measure average exposure over an extended period, typically ninety days to one year. These tests provide a more accurate representation of annual radon exposure and are considered the gold standard for risk assessment.

Long term testing devices include alpha track detectors and long duration electret ion chambers. Alpha track detectors are widely used in residential settings due to their stability and accuracy over long durations.

Alpha track detectors contain a special plastic film that records microscopic damage caused by alpha particles released during radon decay. Over time, these tracks accumulate and are later counted to calculate the average radon concentration.

Because long term tests smooth out daily and seasonal fluctuations, they are particularly useful for confirming borderline short term results or for homes where mitigation decisions require high confidence data.

Long term testing is especially recommended for families with children, homes with basements used as living spaces, and properties being evaluated for purchase where long term occupancy is expected.

Choosing Between Short Term and Long Term Testing

Short term tests are appropriate for initial screening, real estate transactions, and situations where quick results are needed. Long term tests are better suited for understanding chronic exposure risk and confirming results before mitigation.

Health agencies often recommend beginning with a short term test. If results are below the action threshold, periodic retesting may be sufficient. If results are elevated or close to action levels, a follow up long term test provides better decision making data.

In practice, many homeowners choose to use both methods sequentially. A short term test identifies potential risk, and a long term test confirms whether mitigation is necessary.

Interpreting Radon Test Results

Radon test results are reported in picocuries per liter. In the United States, the Environmental Protection Agency recommends action if levels are at or above four picocuries per liter. However, no level of radon exposure is considered completely safe, and many health experts encourage mitigation at lower concentrations, especially for families.

Results below two picocuries per liter are generally considered low risk, though periodic retesting is advised. Results between two and four represent moderate exposure and warrant further evaluation or long term testing. Results above four indicate a clear need for mitigation.

When interpreting results, it is important to consider test duration, placement, and conditions during testing. Improper placement or ventilation changes can affect accuracy.

Common Testing Errors to Avoid

Testing in kitchens, bathrooms, or laundry rooms can produce misleading results due to humidity and airflow. Placing tests near windows, exterior walls, or heating vents can dilute radon concentrations. Testing during major renovations or unusual weather events may also skew results.

Failing to follow closed house conditions during short term testing is one of the most common causes of inaccurate readings. Proper adherence to instructions is essential for meaningful results.

Using At Home Radon Test Kits

At home radon test kits provide a practical and accessible way for families to assess indoor air safety without specialized equipment. Modern kits are designed for ease of use while maintaining scientific reliability.

The Detekt Home radon test is designed to support both short term screening and accurate household assessment, making it suitable for families seeking dependable insight into their indoor environment without complicated procedures.

When using any home test kit, careful attention to placement, timing, and instructions ensures data quality comparable to professional screening methods.

Retesting and Ongoing Monitoring

Radon levels can change over time due to structural settling, seasonal moisture shifts, HVAC changes, and home modifications. Retesting every two to five years is recommended, as well as after major renovations or changes in occupancy patterns.

Homes with previously low radon levels should not assume permanent safety. Ongoing awareness and periodic testing help maintain long term protection, especially in homes where children spend significant time indoors.

Conclusion

Testing for radon is a critical step in protecting family health. Short term tests provide rapid insight into potential risk, while long term tests deliver the most accurate measure of chronic exposure. Understanding how each method works allows homeowners to choose the right approach and interpret results with confidence.

Because radon cannot be detected by human senses, proactive testing remains the only reliable safeguard. With proper testing practices and scientifically validated tools, families can make informed decisions about their indoor air and reduce long term health risks associated with radon exposure.

By Ryan N., PhD