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The technical building code includes radon

This month, since the 8th, the European Directive 2013/59/Euratom, approved four years ago, has come into force, and the deadline for its transposition in Spain was this February. The directive not only affects European Union (EU) governments, but also building codes.

Since the entry into force of this new European directive, governments are obliged to measure radon and mitigate its concentration in cases where it exceeds 300 becquerels per cubic metre, the unit of measurement used for this gas. The directive could have been more demanding, given that the World Health Organisation (WHO) sets the limit for the danger at 100 becquerels (in the USA it is 148 becquerels).

In addition to this, there is also the impact on building codes, which must include measures to prevent the entry of this gas into newly constructed buildings. Not only that, but they will also have to include actions to reduce exposure in existing houses. This appears in the latest update of the DB-HS ‘Health’ of the Technical Building Code (CTE), which even includes subsidies for these corrective measures.

According to data handled by the Nuclear Safety Council (CSN), radon is present in dangerous concentrations in 10% of our buildings.

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What is radon?

It is a tasteless, colourless, odourless gas found in granitic and shale subsoils because the rocks of these types of rocks are rich in uranium, which is the source of this gas. This gas decays radioactively naturally, releasing Polonium-218 and Polonium-214, which are hazardous to health. In fact, according to the WHO, exposure to radon is the second leading cause of lung cancer after tobacco.

According to the Nuclear Safety Council, the areas of Spain with the highest concentration of radon gas are in Galicia (especially Ourense and Pontevedra), followed by Castilla y León, Extremadura, Madrid and certain areas of Castilla La Mancha.

During 2017, technicians from the Ministry of Public Works have been working on a decree for the Technical Building Code to contain the ‘regulatory requirements relating to protection against radon gas in residential buildings’.

Where does it enter houses?

The exposure of houses to radon depends on different aspects, from the local geology (if the soil is granitic), to the access and pathways that facilitate the exhalation of the gas indoors or the exchange of air between indoors and outdoors, which depends both on the type of construction and the ventilation habits we have.

Studies to date reveal that the highest concentrations of radon in dwellings are found mainly in basements, cellars and ground floors, through cracks or crevices, i.e. in structural elements that are in direct contact with the ground. However, there are other routes of entry:

  • The sill: this is the piece of wood on which the roof is raised, located at the top of the walls.
  • The exterior walls: through the interior of its air chamber.
  • Basements: their walls and the entire network of sewerage pipes, together with the sanitary floor slab, can allow gas to enter.

How are buildings protected?

At present, there are various mechanisms for protecting buildings from the threat of radon. One of the simplest measures is the use of insulating materials, waterproofing sheets that provide a real barrier against radon, as well as safeguarding the home from the rigours of the weather.

It is also possible to apply extraction or pressurisation systems, so that air can be extracted from both the foundations and the side walls. In the same vein, it is also possible to use vacuum pumps, thanks to which the radon molecules are extracted from the sealed space.

A fourth option is to expel the gas outside the buildings by constructing a well to act as a suction pit. This must always be accompanied by the sealing of any cracks or fissures to prevent the gas from re-invading the space.