Lung cancer: over 6% of deaths may be caused by radon

Radon in the human body

The radioactive gas radon is one of the most common causes of lung cancer after smoking. A recent study by scientists at the Federal Office for Radiation Protection (BfS) shows what this means in concrete terms: according to the study, some 6.3% of all lung cancer deaths in Germany can be attributed to radon in homes. That's around 2,800 cases per year. The scientists have published their findings in the renowned journal Radiation and Environmental Biophysics.

Radon is produced everywhere in the ground. Even the slightest leak in the floor area of a building is enough to allow the radioactive gas to enter. If radon accumulates in living spaces in this way, residents regularly inhale the gas over long periods of time – and their risk of lung cancer increases. The higher the radon concentration in the indoor air, the higher the risk. Elevated radon concentrations occur primarily in basements and ground floors.

Effective protection against radon is possible

Dr Inge Paulini

"The figures clearly show that radon is a serious health risk," says BfS President Inge Paulini. "The Federal Office for Radiation Protection has long campaigned for protection against radon and provides information on what each and every individual can do to protect themselves and their families. The first step is a radon measurement in your own four walls, which is simple and inexpensive to achieve. If the radon levels are too high, effective protection is possible."

Study reveals regional differences

Estimated average radon activity concentrations (arithmetic mean) of indoor air to which residents of a municipality are exposed in their homes.

The average quantity of radon that inhabitants of a municipality are exposed to in their homes varies significantly from one region to the next. The main causes are the geological composition of the soil and the settlement structure. In Germany, elevated radon concentrations in homes are particularly common in semi-mountainous regions and in the foothills of the Alps.

Accordingly, the analysis by the BfS scientists reveals differences between the federal states: in states with higher average radon concentrations in homes, the proportion of lung cancer deaths caused by radon is higher than in states with lower average levels. At the top of the list are Thuringia (10.0%) and Saxony (9.5%), while the rate is lowest in the city states of Berlin (3.2%), Hamburg and Bremen (3.3% each).

Reducing radon levels across the board

Although the analysis by federal state reveals regional focal points, elevated radon levels can occur in homes anywhere in Germany. Paulini says: "Anyone who detects elevated radon levels in their own home should take action. The study shows how important this is. There are effective – and usually also inexpensive – measures available for reducing radon concentrations."

About the study

The BfS wanted to find out the average level of radon present in German homes.

With their investigation, the BfS scientists built on research projects conducted by their colleagues: in the years 2019 to 2023, extensive work was carried out to survey the radon situation in homes in Germany. Some of this work was commissioned by the BfS, and some was done by the BfS directly. Paulini praises this joint approach as an excellent example of interdisciplinary collaboration and long-term research planning at the Federal Office for Radiation Protection.

In addition to data on the regional distribution of radon concentrations in homes, the researchers also used current data on lung cancer mortality and the smoking behaviour of the population, as well as risk models, to describe the relationship between radon and lung cancer and between smoking and lung cancer. To compensate for the effects of annual fluctuations in the number of deaths, the total number of lung cancer deaths was averaged over the years 2018 to 2022.

In terms of methodology, the BfS scientists based their work closely on a publication from 2008, which found that an average of 5% of all lung cancer deaths – around 1,900 cases per year – were caused by radon in the mid-2000s. The recalculation by the BfS scientists used an up-to-date and improved database which therefore reflects the current situation.

The study "Lung cancer mortality attributable to residential radon in Germany" is available as an open access publication here.

Protection against radon

Increased ventilation helps as an initial measure to protect against radon Source: britta60/Stock.adobe.com

The protective measures against radon are aimed at ensuring that the radioactive gas does not enter a building in the first place or that it leaves the building again quickly. Regular ventilation therefore helps as an immediate measure in the event of increased radon levels. If this measure can reduce the radon concentration sufficiently, then a technical ventilation system represents a sensible permanent solution.

To prevent radon from entering a building, one option is to seal entry points such as cracks or pipe penetrations in the area of the building that is in contact with the ground. In more serious cases, the radon-containing air can be extracted from beneath the building. Radon specialists can assist with the planning and implementation of protective measures.