Long-term measurement
You always begin by performing accredited long-term measurement over a minimum period of 2 months. If the results indicate elevated radon levels, proceed to Step 2.
Dosimeters and digital detectors for the home
The first thing you should do as a homeowner when you want to determine the radon level in your home is to carry out accredited and approved long-term measurement using dosimeters. If high levels of radon are confirmed, an inspection should be performed, followed by radon decontamination.
In order to ensure that radon decontamination and measures are working, the homeowner should continuously monitor radon levels after the implementation of measures. This can be done by installing a digital radon detector that is linked to a cloud database. By measuring how radon levels vary over time, it is possible to tell whether or not the measures are actually working. This gives you a complete overview of radon levels once action has been taken.
To be on the safe side, it is a good idea to follow up on measures taken by measuring the average annual value using an accredited and approved method. This is important both for health reasons and, for example, if you want to sell your house. It is also a requirement to be able to apply for a grant to help with the cost of radon decontamination (if these are available on your market).
If you have a limited amount of time available (e.g. because of a house sale/purchase), you can opt for short-term measurement. This type of measurement takes just 7–10 days. However, the results should be regarded as an indication, rather than a more precise measured value.
About radon and health risks
The earth’s crust contains a number of different radioactive substances that were created when the earth was formed. Of these, there are three isotopes deemed to be of particular interest from a radiation safety perspective: thorium-232, uranium-235 and uranium-238. Each of these isotopes has a long half-life and during a series of transformations (into stable substances), known as a decay chain, they are converted into the noble gas radon. As a noble gas tends not to react with other substances, the radon can spread from the ground to indoor air.
A cause of lung cancer
Radon is radioactive and forms so-called radon progeny as it decays. These are charged metal ions that tend to react to and attach to dust particles and aerosols (finely dispersed microscopic particles). Radon progeny are also radioactive and emit alpha radiation as they decay. The unbound radon progeny that are present in inhaled air are particularly harmful, as they tend to become trapped in the respiratory tract and lungs.
The alpha radiation that is emitted inside the body is harmful and can cause tissue damage, which in turn can lead to lung cancer. The World Health Organization (WHO) estimates that the number of cases of cancer caused by exposure to radon each year is approximately 230,000.
About various radon isotopes
Radon-219 is also called “actinon” and is the radon isotope formed as part of uranium-235’s decay chain. As it has a half-life of just four seconds, it tends not to be encountered in indoor environments. In other words, it does not have the time to be transported as a noble gas from the ground to indoor air before it decays into polonium-215.
Radon-222 is derived from uranium-238 and is the isotope commonly referred to when talking about and working with radon. It has a half-life of almost four days (3.8 days), which gives the gas plenty of time to enter a building’s indoor air. Consequently, at a certain concentration it can pose a health risk to people who spend time in an indoor environment where it is present. Radon-222 decays to form polonium-218, which is an alpha emitter with an energy of 6.00 MeV.
Common errors when measuring radon
With instruments
- The instrument has not been calibrated
- Disregarding the fact that radon progeny must decay in the measurement chamber before new measurement can be performed
- Moving the instrument between different measuring points too quickly
- Not waiting for equilibrium between the radon and the radon progeny
With passive detectors
- The dosimeters are incorrectly positioned
- Too few measuring points are used
- The dosimeters are not sent for analysis immediately after measurement is complete
- The dosimeters are analysed by an unaccredited laboratory