Radon

Radon has been classified as a known pulmonary carcinogen by the WHO since 1987. The risk of developing lung cancer associated with radon exposure depends on the concentration of radon in the home and the time spent in rooms where the concentration is high. The higher the radon concentration and the longer the exposure, the greater the health risk.

Today, lung cancer is the only scientifically recognised health effect of radon exposure (IRSN 2021).

Radon and tobacco are both pulmonary carcinogens. Smoking is the leading risk factor for lung cancer. However, the combined exposure to the two factors multiplies the negative effects.

As the air pressure inside a house is often lower than in the subsoil, air tends to flow from the ground into the house to equalise the pressure. This difference in pressure is more prevalent in winter when the house is heated. If the interface between the building and the ground is not sealed, air containing radon in varying amounts content can get into the house. Any openings, such as piping and cracks, even if they are invisible to the naked eye, can let radon in.

There are no obvious symptoms of radon exposure. Radon does not cause coughing, headaches or any other symptoms. The health risks of radon are to be considered for long-term inhalation of high concentrations. In this case, radon leads to a higher risk of developing lung cancer. This increase is proportional to cumulative lifetime exposure. Therefore, the risk is associated with both the concentration of radon and the duration of exposure.

There is no legal obligation to measure the radon in your house, even if you live in a radon priority area (see radon map (Pdf, 135 Kb)). Nonetheless, measuring radon allows you to identify a potential health risk and to remedy it, if necessary.

However, since May 2019, measuring radon levels has been required in some workplaces. The workplaces concerned are specified in the radiation protection law of 28 May 2019 and the Grand-Ducal Regulation of 1 August 2019.

Either the tenant or the owner/landlord can apply to have a radon measurement done. It should be noted that measuring is done free of charge by the Health Directorate's Radiation Protection Division.

• Application form

The radon concentration in a house depends on a number of factors, including:

• the geological formation and permeability of the soil;
• the sealing and ventilation characteristics of the building;
• the occupants' lifestyle.

As each building is different and since everyone has their own way of life, radon concentrations can vary considerably between two houses, even if they are built on the same soil (given that soil permeability also varies locally). The only way to know the radon concentration in your house is to get it measured.

• Application form

Fill in the application form. The measurement kit will be sent to you by post. Measurement is free for all Luxembourg residents.

In a private home, the first radon measurement should be done in at least two main rooms, one of which is typically on the ground floor – with the exception of the kitchen – and the other in a bedroom. The measurement period is 3 months, preferably between October and the end of April. Measurement in uninhabited rooms such as cellars or attics is not necessary. Important information about the rooms where measurements must be taken in the workplace can be found in the Measurement Guide.

An interpretation of the measurement results is included in the analysis report. Additional information can be requested from the Radiation Protection Division by telephone or email.

There are several things you can do yourself. How effective they are depends on the radon concentration. The higher the radon levels, the more complex effective measures are. In this case, we recommend contacting an expert. Often, several actions need to be combined to achieve the desired reduction in radon concentration.

• Increasing air renewal inside the house is the first step. This reduces the radon concentration and, at the same time, improves general air quality. If you have natural ventilation, we recommend opening the windows for at least ten minutes to create a flow of air in the house, and doing this two or three times a day.
• If you have a mechanical ventilation system, make sure it is properly maintained to prevent the inlet and outlet filters getting clogged and to ensure that the volume of air changed is appropriate. You may also want to increase the flow of air.
• Increasing the renewal of air in the substructure of the house helps to evacuate radon before it can get into inhabited rooms.
• Blocking radon inlets helps to reduce the amount of radon that gets in. It is important to block all cracks and openings between the subsoil and the cellar (or crawl space) and between the cellar and the ground floor.

Every house is different. This is why a site visit by an expert can be very helpful. Here is a list of building professionals who are familiar with radon-related issues.

• List of experts (Pdf, 286 Kb)

It is impossible to provide a general cost. The factors that affect the price are the radon concentration and the general condition of the house. However, domestic radon remediation should not cost more than a few thousand euros. A subsidy can be applied for from the Ministry of Housing.

When renovating an existing house, the most important thing is to prevent radon getting into the building. An airtight envelope around the house that goes down to the ground is essential. In addition, a regular supply of fresh air ensures that the atmosphere inside the house remains healthy, and also dilutes the concentration of radon. Last but not least, it may be useful to take radon measurements before and after renovation.

• Find out more...

At present, radon levels measured in low-energy and passive houses in Luxembourg are very low. This suggests that current construction methods provide sufficient protection against radon. However, as there is no long-term data on the tightness of these constructions, installing a radon barrier provides additional protection. This barrier is a sheet that is impermeable to radon, made up of different layers (polyethylene, aluminium, etc.). 

In this case, the radon barrier (radon membrane) must be installed over the entire surface area of the building that is in contact with the soil. The sheets of the radon barrier must be carefully glued together and inserted into the perimeter of the building and in the interior walls. As a result, installing a radon barrier requires a certain amount of experience and should therefore be done by a specialist. The radon barrier under the foundations prevents radon from getting inside buildings. Radon can pass through traditional damp proof courses. Installing a radon barrier proves highly effective for new builds.

A soil radon measurement gives no information about the subsequent radon concentration in your house. The building's characteristics and the lifestyle of the occupants greatly influence the radon concentration. However, if you build a house in a radon area, in terms of prevention, installing a radon barrier under the concrete foundations really helps to stop radon getting into the building. In any case, once construction is completed, it is recommended that you measure the radon concentration in your house.

You can ask the owners if they have measured the radon concentration in the house. If they have, check that no work has been done since then that could affect the house's permeability and/or ventilation. These factors play an important role in terms of radon concentration. If no measurement has been taken, and if the house is in a radon area, you can contact the Radiation Protection Division when you buy the house to get a measurement done. Note that a representative radon measurement is done over a period of three months between October and the end of April. The radon concentration can be estimated by doing a shorter measurement. It is important to note that radon remediation is often relatively simple.

Some construction materials, such as granite, can be a source of ionising radiation because of the natural disintegration of the radioactive elements contained in these materials. One of the products of this disintegration is radon. But exposure to radon from construction materials is generally quite low and poses no real danger to inhabitants. If you are in any doubt, get a radon measurement done.

Even if vegetables grow in soil that is rich in radon, they do not become radioactive themselves. The same goes for food stored in a cellar where the radon concentration is high. You can therefore eat food grown in your garden or stored in your cellar with no risk to your health.

No, radon measurement is not currently mandatory before selling a house.

There are several remediation options if the radon concentration is high. Because of their experience, the experts on our list can advise you. At present, every house in Luxembourg with high radon concentrations has been successfully rectified. The value of your house is therefore not affected by the radon result.

To find out the radon concentration in your office, get a measurement done. Radon levels are often highest in rooms in contact with the soil. However, not all cellars necessarily have high concentrations.

The European Radiation Protection Regulation introduced the principle of a reference level to regulate situations in which a limit could not be applied. As a high radon concentration is a natural phenomenon, it cannot be prohibited (like exceeding a limit). Nonetheless, a target can be defined with the aim of reducing exposure as much as possible to below the reference level, and promoting optimisation below this level. In Luxembourg, the reference level is set at 300 Bq/m³.