Testing for radon gas within a property is the only way to understand if harmful levels of radon are present, though many are left wondering how often a test should be carried out.

Whilst some may think that a single test is enough, radon levels are not fixed. They can fluctuate over time due to environmental conditions and building alterations. Understanding when and how often to test is key to ensuring the occupiers protections.

Why Test More Than Once

A single radon test, especially a short term one, provides a snapshot of conditions at a specific point in time. Changes in season, ventilation, soil condition and alterations to building structure can all contribute to radon level fluctuation.

Relying on a one-time result may create a false sense of security, while performing ongoing tests will help confirm that radon levels remain within acceptable limits.

Testing Frequency

For most residential properties, the following approach is considered good practice if the property has been identified as lying in a radon ‘affected area’.

· Initial Test: As soon as possible, especially if the property has never been tested

· Follow-Up Testing: At least once every 10 years to confirm levels remain stable

· After Installing a Mitigation System: To verify that it is working correctly

· Periodic Re-Testing: When a mitigation system is in place, re-test once every two years

Certain situations call for more regular testing.

Renovations or structural changes such as extensions, installation upgrades, new flooring, or changing in ventilation can all affect how radon enters and behaves within a building. Installing extractor fans or air conditioning units, sealing drafts, or improving air tightness can all alter airflow and pressure, potentially influence radon levels.

If earlier tests showed radon levels approaching recommended limits, it is worth re-testing more frequently.

Testing After Installing a Mitigation System

Testing after installing a radon mitigation system confirms that the system is functioning correctly, radon levels have been reduced effectively, and no additional adjustments are required.

Even after successful installations, periodic re-testing is essential. Systems can become less effective over time due to wear, building changes or environmental factors.

Practical Approach for Property Owners

A simple proactive approach can make a significant difference:

· Test your property if you have not done so before

· Retest periodically rather than relying on a single result

· Test again after any major building changes

· Confirm performance after installing mitigation systems

Treating radon testing as a routine part of property maintenance helps ensure that protection is ongoing. Regular testing provides reassurance, identified potential issues early and ensures that any mitigation measures continue to perform effectively.

By adopting a regular, planned testing approach, homeowners and property managers can take control of radon risk and maintain a healthier indoor environment.