Radon detector calibration: when it is needed, how often to do it and why it matters

Measuring radon means producing technical data that may influence important decisions: environmental assessments, workplace checks, remediation planning, periodic monitoring and technical documentation.

For this reason, owning a measurement device is not enough. It is also important to know whether that device is measuring reliably.

Radon detector calibration serves exactly this purpose: it checks the behaviour of the instrument by comparing it with known references, helping users better understand its performance and increasing confidence in the data it produces.

In this guide, we explain what it means to calibrate a radon detector, how often calibration should be performed, what a calibration report usually contains and why this process is especially important for professionals, companies, technicians and laboratories using instruments for radon measurement.

Why radon measurements must be reliable

Radon is a naturally occurring radioactive gas that can accumulate indoors, especially in basements, semi-basements and poorly ventilated rooms. Radon measurement has become an increasingly important topic for homes, workplaces, schools, public buildings and professional environments.

In Italy, radon is regulated by Legislative Decree 101/2020, which implements the European radiation protection framework. Reference levels for indoor radon are linked to the annual average concentration and apply to both dwellings and workplaces.

The Italian National Radon Action Plan 2023–2032, adopted by Prime Ministerial Decree on 11 January 2024, also defines the national strategy to reduce long-term risks from radon exposure in homes and workplaces.

In this context, measurement quality becomes essential.

A radon concentration value is not just a number: it is technical information that can be used to assess a risk, plan an intervention or demonstrate compliance with specific requirements. If the instrument is not checked over time, the reliability of the data may be reduced.

Calibration: what does it really mean?

In everyday language, the terms “calibration” and “checking” are sometimes used loosely. In technical terms, calibration refers to comparing an instrument with a known reference.

Calibration makes it possible to determine the metrological characteristics of the instrument by evaluating the difference between the value indicated by the device and the reference value. In general, calibration activities help improve measurement reliability and support metrological traceability to national or international standards.

Applied to radon measurement, this means exposing the instrument to controlled radon-222 activity concentration conditions and evaluating how the instrument responds.

The result is not an automatic repair or adjustment of the device. Instead, calibration provides a technical snapshot of the instrument’s behaviour at that specific time.

In other words, calibration helps answer questions such as:

• is the instrument measuring correctly?
• how much does it differ from the reference value?
• is the data produced compatible with the intended use?
• should a correction or further technical evaluation be considered?

How often should a radon detector be calibrated?

The calibration frequency depends on how the instrument is used, how intensively it is used, operating conditions, internal procedures and the level of measurement confidence required.

For professional use, periodic calibration is generally recommended, often on an annual basis. RadonStar explains in its FAQ that calibration is a “snapshot” of the instrument’s characteristics at the time of testing and recommends performing it at least once a year.

This periodic approach is particularly useful when the instrument is used for:

• measurements in workplaces;
• environmental monitoring campaigns;
• technical assessments for clients;
• checks before and after remediation work;
• repeated professional measurement activities;
• comparisons between different instruments;
• technical documentation that needs to be retained.

An instrument used only occasionally may seem less exposed to wear, but even in that case it is useful to periodically check its behaviour. Sensors, electronics, firmware, batteries, transport and environmental conditions can all affect performance over time.

What happens if a radon instrument is not calibrated?

An uncalibrated instrument may continue to display readings, but this does not necessarily mean that those readings are reliable.

Over time, any measuring instrument may change. The sensor may respond differently than in the past, the electronics may be affected by ageing, or the device may have been exposed to impacts, transport, unsuitable environmental conditions or long periods of inactivity.

In radon measurement, this can lead to several problems.

Less reliable data
The displayed value may differ from the actual value more than expected.

Reduced comparability between measurements
If multiple instruments are used in the same project, lack of calibration makes it more difficult to compare results.

Weaker technical documentation
For professionals, being able to demonstrate that the instrument has been checked is an important element of credibility.

Decisions based on uncertain data
Unreliable data may affect risk assessment, remediation choices or verification of remediation effectiveness.

Lower trust from clients
When working with companies, building managers, technicians or organisations, the quality of the instrumentation is part of the overall quality of the service.

Calibration does not eliminate uncertainty, but it helps users understand and manage it in a technical and documented way.

What does a radon calibration report include?

The calibration report is the document that records the results of the test performed on the instrument.

In general, a calibration report may include information such as:

• instrument identification;
• model and serial number;
• test conditions;
• references used;
• results obtained;
• any deviations observed;
• associated measurement uncertainty;
• date of calibration;
• information about the laboratory or calibration system.

At the end of the RadonStar calibration process, the customer receives the calibration report by email. The service is organised through scheduled calibration sessions dedicated to specific categories of devices.

The report should not be seen as a simple administrative attachment. It is a technical document that helps demonstrate that the instrument has been checked and that its performance has been evaluated under defined conditions.

Calibration certificate and calibration report: are they the same thing?

In everyday language, people often refer to a “calibration certificate”. However, it is useful to distinguish the terminology.

The document produced at the end of the test may be called a calibration report or a calibration certificate depending on the context, the type of laboratory and the procedures applied.

What matters most is not only the name of the document, but its technical content:

• does it clearly identify the instrument?
• does it report the test conditions?
• does it show the results obtained?
• does it allow the behaviour of the instrument to be assessed?
• does it provide useful information for traceability and instrument management?

For those who use radon instruments professionally, this document becomes part of the instrument’s technical documentation and should be kept together with measurement records, internal procedures and any reports prepared for clients.

Which radon instruments can be calibrated?

RadonStar offers calibration sessions organised for specific categories of radon measurement instruments. Sessions are scheduled according to a dedicated calendar, and each session is intended for a specific group of devices.

The instrument categories currently listed on the RadonStar website include:

• Corentium Pro / Corentium Plus;
• RadonEye / RadonEye Plus2;
• EcoQube.

For instruments not included in the standard sessions, RadonStar provides a special calibration request option.

This session-based organisation helps manage laboratory activities more efficiently and allows customers to choose the most suitable time window for sending their instrument.

How the RadonStar calibration service works

The RadonStar service is designed to make the calibration process simple and easy to plan.

In summary, the operational flow is as follows:

1. the customer checks the calibration calendar;
2. the customer chooses the session available for their instrument;
3. the service is booked;
4. the instrument is shipped according to the instructions received;
5. RadonStar performs the calibration during the scheduled session;
6. the instrument is returned;
7. the customer receives the calibration report by email.

RadonStar defines a calibration session as a time window that starts with the deadline for requesting the service and ends with the return of the calibrated instruments and the delivery of the calibration reports to customers.

This approach is particularly useful for professionals and companies, as it allows them to plan instrument downtime and organise their measurement activities accordingly.

Why calibrate a new instrument?

A new instrument may be fully functional, but this does not mean that checking its behaviour is unnecessary.

Initial calibration can provide a documented reference from the very beginning of the instrument’s operational life. This is particularly important if the device will be used for professional activities, technical comparisons or measurements requiring documentation.

Calibrating a new instrument helps to:

• create a metrological history;
• verify behaviour before operational use;
• document the initial condition of the instrument;
• compare future calibrations over time;
• increase confidence in the data produced.

For users managing multiple devices, initial calibration is also useful for checking the consistency of the entire instrument fleet.

Calibration and professional reputation

Those who measure radon do not simply provide a reading: they provide technical data.

For this reason, instrument quality and metrological management are part of a professional’s reputation.

A client may not know every technical detail of radon measurement, but they can easily understand the difference between an instrument used without checks and an instrument that is periodically calibrated.

Being able to state that a radon detector has undergone periodic calibration helps communicate seriousness, technical care and responsibility.

This is even more important when the data is used to:

• assess exposure in a workplace;
• support a remediation project;
• compare measurements before and after mitigation;
• prepare documentation for a client;
• manage internal quality checks.

Calibration, therefore, is not only a technical activity. It is also a tool for building trust.

Frequently asked questions about radon detector calibration

Is radon detector calibration mandatory?

It depends on the context of use, applicable procedures and client requirements. In any case, for professional use it is strongly recommended to schedule periodic checks of the instrument, because data quality also depends on the reliability of the equipment used.

How often should I calibrate my radon detector?

For professional use, annual calibration is a prudent choice and is consistent with good instrument management. RadonStar recommends carrying out calibration at least once a year.

Can I calibrate an instrument that is not listed in the calendar?

Yes. If the instrument is not included in the available standard sessions, you can use the special calibration request available on the RadonStar website.

How long does calibration take?

It depends on the chosen session and the available calendar. The session includes the period for requesting the service, sending the instrument, performing the calibration, returning the device and issuing the calibration report.

Does calibration automatically adjust the instrument?

Not necessarily. Calibration evaluates the behaviour of the instrument against a reference. Any adjustment, maintenance or operational decision depends on the device type, the result obtained and the applicable procedures.

Should instruments such as RadonEye, Corentium Pro or EcoQube also be calibrated?

Yes, especially if they are used for professional measurements or in activities where data reliability is important. RadonStar organises sessions dedicated to specific categories of instruments, including those listed on its website.

Conclusion: reliable measurement starts with a checked instrument

Radon measurement is a technical activity that requires care, method and reliable instruments.

Radon detector calibration helps users better understand instrument behaviour, document performance and increase confidence in the data produced.

For professionals, companies and technicians, calibrating instruments periodically means working with greater awareness and offering clients a more solid, transparent and credible service.

Do you need to calibrate your radon detector?
Check the RadonStar calibration calendar and choose the next available session for your instrument.