Radon monitoring

Detecting and monitoring radon in homes in Cornwall and the South West. How to choose a radon detector.

Measuring radon

There are many different ways of measuring radon. Detection methods range from complex scientific instruments, to simple passive detectors, or carbon canisters. For domestic purposes, measurements to within 10Bqm-3 are sufficient as measurements finer than that are not required for understanding radon and its remediation in a property. For normal home and workplace measurement passive radon detectors and electronic radon monitors are most widely used.

Radon detectors are safe and simple to use: e.g., they can sit on a shelf. The hollow plastic shell contains a piece of clear plastic that records the damage caused by radon. A radon detector does not emit anything and does not collect anything dangerous. However, a radon detector can be damaged by heat or submersion in water and should not be opened.

Radon detectors compared

Passive detection provides a standardised result on printed paper. It is used for completing standardised tests for radon in properties in the UK. Passive detectors do not have a readable display, and need to be sent to a laboratory for analysis and results, so results can be delayed by weeks at times. A passive radon detector can be placed for periods from 7 days up to 1 year, but usually they are placed for a minimum of 3 months to reduce errors and allow an annual average calculation to be applied.

Electronic monitors can begin giving radon measurements on their display panel after 5-6 hours. They produce a clear reading that the user can read instantly, and is updated hourly. However, they do not produce a paper document that can be used for legal transactions, and are not seasonally corrected. They are not used as the standard method for recording radon levels in a property in the UK.

Measuring radon in the home

Domestic properties should aim to keep radon levels below 200Bqm-3 to comply with UK Government guidelines; known as the radon Action level. The standard means of determining if the radon in the home is below the domestic Action Level is to use two passive detectors over a 3 month period. Often residents first become aware of radon when selling or buying a property, when they might be asked to supply/ or be supplied with radon information on their property.

To conduct a standard domestic test, one detector is placed in the main Living Room, and one in the main bedroom. A minimum of 3 month placement is required to allow a seasonal correction to be applied, resulting in an Annual Average result for the whole property. Passive detectors need to be analysed in a laboratory to get the result. A paper document is supplied to the purchaser to state the radon levels in each room, and an Annual Average result.

If an occupant/owner requires information for themselves, and do not require paperwork to authenticate their radon results, then an electronic monitor can be used. These can produce results within a day, and will show the reader a short-term and various longer-term measurements on an on-going basis, depending on the model. This type of instruments can be used to determine averages across a house in a short period of time, but the results can be misunderstood if understanding of the basic monitoring principles (above) are not adhered to. The user must be sure that they keep good records of results and the monitoring period to reduce inaccuracy and provide good evidence.

It is recommended that your monitor results be discussed with a radon specialist before any remedial action is undertaken, as the results can lead to confusion and misinterpretation, without a wide knowledge of radon and its remediation.

If your radon measurements show your property is above the 200Bqm-3 action level, then radon remediation is required.