What is radon gas and how does it affect health?

The ongoing monitoring study carried out by the Galician Radon Laboratory, of the University of Santiago de Compostela, shows that in two out of three municipalities in this region there is a high level of exposure to radon. Furthermore, according to the Nuclear Safety Council's map of radon potential in Spain, this problem is also significant in the Pyrenees and the western area of Extremadura and Castilla y León. But what is radon and why should we care?

What is radon gas?

Radon is a gas that has no colour, odour, or taste and is also soluble in water. This noble gas is also inert (it does not react with other chemical elements) and is released naturally by the radioactive decay of uranium present in soils and rocks. Some rocks, such as granite (of which there is a significant presence in the soils of the northwest of the Iberian Peninsula), have more uranium than others and, therefore, release more radon. But the most problematic element in the description of this gas is not its lack of colour or its origin but its radioactivity.

Once it passes into the air, radon decays, losing energy in the form of radioactive particles. In breathing in these particles, according to the World Health Organization (WHO), there is a risk that the radioactive elements will be deposited in the cells of the airways, resulting in damage to DNA and causing lung cancer in the long term. The good news is that radon is quickly diluted in the open air and with certain good practices its risk to health can be eliminated.

How is radon detected?

Outdoors, radon doesn't cause major problems, but everything changes if this gas starts to accumulate inside our home. As the concentration increases, so does the potential risk to health. However, due to its characteristics, it cannot be detected with the naked eye, or by any other human sense.

So the only way to determine whether we are breathing more radon gas than we should is to do a test or acquire a detection device or hire an expert to measure it. In Spain, the Nuclear Safety Council has accredited a number of entities to perform these measurements.

What are its health impacts?

Radon concentrations in homes vary widely, from a few becquerels per cubic meter of air (the unit in which this gas is measured, abbreviated as Bq/m3) to several hundred. There is not a building that does not contain at least a minimal amount of radon in its interior and the low levels do not pose a health risk.

However, the WHO specifies that prolonged exposure to concentrations exceeding 100 Bq/m3 can begin to have significant effects. The higher it is, the greater the risks. Many jurisdictions, including Spain's, recommend not exceeding 300 Bq/m3.

The WHO's International Agency for Research on Cancer classifies radon as a group 1 carcinogen. In other words, an element whose carcinogenic potential in humans is scientifically proven.

According to the WHO, radon is in fact one of the leading causes of lung cancer: Every 100 Bq/m3 increase in the concentration of this gas to which a person is exposed entails a 16% increase in the risk of lung cancer. There is also a 25-fold increase in the probability of falling ill among smokers.

How can the presence of radon gas in our home be reduced?

According to the WHO, radon concentrations in buildings depend on the geological characteristics of the place where they are located, the routes that radon can find to infiltrate homes, its release from the building materials themselves and the air change rate in the home.

Taking this into account, the organisation has published a series of tips to reduce the presence of radon gas in our home.

Tips for Reducing Radon in Homes

Radon passes from the soil to the interior of buildings through cracks, junction points between walls, spaces around pipes or cables, small pores in materials, and other cavities. The closer the home is to the ground, the higher the radon concentration. Thus, there is usually more gas in basements, cellars and ground-floor homes.

Ventilation: The first (and easiest) step

Radon concentration increases at night and decreases during the day. For low concentration levels of a few hundred Bq/m3, providing natural ventilation for 15 minutes in the morning is an effective measure.

But for higher concentrations, the WHO advises construction modifications. In Spain, these are detailed in the Technical Building Code.

1. Increase the ventilation of the subfloor. A continuous flow of air under the building structure must be ensured.
                
2. Install a mechanical radon evacuation system in the basement or foundation.
                
3. Prevent it from leaking from the ground floor into the rooms by means of protective barriers.
                
4. Thoroughly seal floors and walls.
                
5. Improve the general ventilation of the building and common areas.