Radon

Radon and cancer

As radon^[1] forms naturally by radioactive decay inside minerals, part of it escapes into the atmosphere and indoor air, where it becomes a potential hazard to the occupants, exposed mainly through inhalation (Joint Research Centre, 2019). Radon and its decay products are known carcinogens, causing, or contributing to, lung cancer, a risk enhanced by exposure to air pollution and smoking. Although cancer risks from radon are limited to exposure to relatively high and sustained indoor concentrations, radon is one of the leading causes of lung cancer (Ruano-Ravina et al., 2017). 1.2-1.9% of all cancer cases, and 1 in 10 lung cancer cases in Europe may be due to indoor radon exposure (Darby et al., 2005; Brown et al., 2018; IARC, 2018; Couespel and Price, 2020). According to Global Burden of Disease study data, around 19,000 lung cancer deaths in Europe in 2019 may have been due to naturally occurring indoor residential radon (Murray et al., 2020). The risk of lung cancer increases in non-smokers by about 11-16% for exposure to every additional 100Bq/m³ (a measure of exposure to radiation) increase in long-term average indoor radon concentration (Ruano-Ravina et al., 2017; WHO, 2021b). While the association of radon with other types of cancer has been studied, the evidence is still inconclusive.

Although radon comes from natural sources, exposure can be reduced in existing and new buildings, and radon prevention should be considered at the design stage in radon-prone areas. WHO (2021b) lists technical solutions that can significantly reduce radon levels in existing buildings, such as increasing under-floor ventilation, installing a radon sump system, preventing radon passing from the basement into living spaces, sealing floors and walls, and improving ventilation. Recommended policy solutions include providing information on radon levels and health risks, establishing radon concentration reference levels, including radon prevention in building codes, radon measurement testing protocols and programmes, education on and subsidies for radon reduction measures, and including radon as a risk factor in national strategies related to cancer control, tobacco control, indoor air quality and energy conservation.

Trends in exposure to radon in Europe

The spatial distribution of indoor radon concentrations across Europe reflects the underlying geology, with high indoor concentrations found in granitic zones and areas with certain types of rock. Climatic and some anthropogenic factors also contribute to indoor radon concentrations, but their spatial distribution is still unclear (Joint Research Centre, 2019). Radon concentrations also increase with depth, which contributes to high levels of occupational exposure in some types of mining activities and higher radon concentrations in ground and lower floors in dwellings (Kropat et al., 2014). There are no robust data on trends in indoor radon concentrations over time, although some studies suggest that improvements in insulation in dwellings may in fact have led to an increase in radon levels, with older buildings having lower indoor radon concentrations (Ringer, 2014; Baeza et al., 2018; Florică et al., 2020). Specifically, energy efficiency-oriented retrofitting, such as replacing old windows with energy-efficient double-glazed ones, insulating walls and ceilings, or replacing old doors with better-sealing ones, may reduce ventilation and increase buildings’ airtightness, thus increasing indoor concentrations in radon-prone areas (WHO Europe, 2009; Pampuri et al., 2018; Symonds et al., 2019).

What the EU is doing about radon

The Basic Safety Standards Directive (EU, 2013) introduced for the first time legally binding requirements on protection from exposure to natural radiation sources and mandated all EU Member States to establish national radon action plans, define reference levels for indoor radon concentrations in dwellings and workplaces, and identify and delineate radon priority areas. Europe’s Beating Cancer Plan supports Member States in implementing the requirements on protection from ionising radiation, particularly radon, which causes a substantial number of lung cancers. One of the 12 messages of the European Code against Cancer calls upon citizens to “Find out if you are exposed to radiation from naturally high radon levels in your home. Take action to reduce high radon levels.”

Cover photo © TakeActionOnRadon on pixabay.com