Warning: “Radon is all around us. You are now entering a radioactive area.”. It could be the sign at your front door. Would you stay – or would you turn round into the open air?
It is an invisible, odourless gas that seeps out of the ground and it is called radon.
Radon is a natural radioactive gas produced by the decay of uranium 238, which is present throughout the Earth’s crust. In the open air, radon causes no problems. We all breathe it. But it can seep into buildings through cracks and holes in the foundations, where it can rise up to dangerous levels.
The most important pathway for human exposure is permeation of radon gas into buildings, but radon from water, outdoor air and construction materials can also contribute to the total exposure. What makes it dangerous is that, being odourless and colourless, it is easy to ignore. Professor Sir Richard Peto, a well-known cancer epidemiologist, once remarked: “If only it were blue and people could see it they would take it seriously, but unfortunately it isn’t.”
At home we are at risk from unsafe exposure to indoor radon gas, which may cause lung cancer. Smoking is the leading cause of lung cancer. Radon is the number one cause of lung cancer among non-smokers. The largest and most rigorous study of radon, published in 2004, showed that the gas is responsible for about 20,000 deaths from lung cancer in the European Union each year. The research combined the results from 13 studies and showed that smokers were at greatest risk. Worldwide, radon causes a million deaths every decade. Neil McColl, of the HPA’s Centre for Radiation, Chemicals and Environmental Hazards, says: “The scientific evidence has shown that the lung cancer risk is proportional to the long-term exposure to radon. There is no safe or unsafe level. We want to keep our focus on homes above 200 becquerels (bq) but we also want to make sure that people who are reducing the level should not think that below 200 they are safe. The risk is smaller, but it is not zero – particularly if they are smokers or ex-smokers.”
Previous warnings about the risks have been based on evidence from miners who were exposed to high levels of radon while working underground. Current policy in house building is to identify areas where radon levels are high, seal the foundations of new homes with gas-resistant membranes and advise existing home owners how to reduce their exposure by building a radon sump. Home owners have to create a radon sump by digging below the foundations and installing a fan and pipe to blow the gas to the outside. But nowaday it’s not safe to focus on radon high radiation. The national policy could force the installing of sealed membranes in all new homes, regardless of where they are built.
Indoor pollution, much more than tobacco smoke
Many of us might spend up to 90 % of our day indoors — at home, work, school or in the cars. The quality of the air we breathe indoors also has a direct impact on our health. What determines indoor air quality? How can we improve indoor air quality? The quality of air in our homes, work places or other public spaces varies considerably, depending on the material used to build it, to clean it, and the purpose of the room, as well as the way we use and ventilate it.
Smoking is not the only source of indoor air pollution. Erik Lebret from the National Institute for Public Health and the Environment (RIVM) in the Netherlands says “Air pollution does not stop at our doorsteps. Most outdoor pollutants penetrate into our homes, where we spend most of our time. The quality of indoor air is affected by many other factors, including cooking, wood stoves, burning candles or incense, the use of consumer products like waxes and polishes for cleaning surfaces, building materials like formaldehyde in plywood, and flame retardants in many materials. Then there is also radon coming from soils and building materials.”
According to the latest report by the World Health Organization (WHO) titled “Ambient Air Pollution: a global assessment of exposure and burden of disease”, air pollution (outdoor and indoor) is the main environmental risk factor for the health of the world population. “Between 1930 and 2000 the global production of man-made chemicals increased from 1 to 400 million tons a year – says Professor Alessandro Miani, President of SIMA ONLUS – and in the last 50 years man has released about 80 thousand new chemicals into the environment “.
The indoor air is basically the same as the external air, but with different quantities and types of contaminants. The health effects of exposure to indoor air pollutants are a function of several factors: time spent in a certain environment, the actual air pollutant concentration, temperature and humidity levels. Since most people spend 85–90 % of their time indoors, indoor sources actually provide most of the personal exposure to certain chemicals. Measures to improve indoor air quality have to be part of a comprehensive management strategy, taking account of climate and outdoor air quality, building materials and technologies, knowledge of behaviour patterns of the occupants, including use of consumer products, as well as energy and sustainability policies.
Regulators, as well as many scientists, didn’t take much notice of contaminant intrusion until the 2000s. At that time, awareness had grown about the hazards of radon. The average person is not likely to detect radon intrusion. You need sophisticated instrumentation to measure low concentrations that are involved.The World Health Organization concludes that radon causes lung cancer in Europe, North America and Asia. The analyses assume that the lung cancer risk increases proportionally with increasing radon exposure.
This assumption has been questioned. As many people are exposed to low and moderate radon concentrations, the majority of lung cancers related to radon are caused by these low exposure levels rather than by higher concentrations (WHO). Most of the radon-induced lung cancer cases occur among smokers due to a strong combined effect of smoking and radon. WHO proposes a reference level of 100 Bq/m3 to minimize health hazards due to indoor radon exposure (WHO). However, if this level cannot be reached under the prevailing country specific conditions, the chosen reference level should not exceed 300 Bq/m3.
Indoor radon pollution mapping in dwellings
In 2006, the Joint Research Centre of the European Commission launched a project to map radon at the European level, as part of a planned European Atlas of Natural Radiation starting with a map of European indoor radon concentrations. Although a few uninhabited areas remain, the reason for which is that radon surveys are still ongoing, or national surveys have concentrated on high-radon areas.
Almost all European countries have monitoring programmes for radon. Clearly, radon monitoring and reduction strategies are best developed in countries with an established radon problem. Radon mitigation in these countries includes national information systems, guidance documents for buildings and local and national radon maps.
The majority of European countries do not have different policies for the various population groups — only a few countries make distinctions between children and the rest of the population by establishing lower reference levels for radon in schools and kindergartens or offering additional financial support for remediation to reduce children’s exposure.
The European Commission issued a Recommendation (EC, 1990) on the protection of the public against indoor radon exposure (90/143/Euratom) in order to harmonize Member States’s provisions for the application of the basic safety standards for health protection against the dangers arising from ionizing radiation. This Recommendation gives guidelines for public information, an indoor radon reference level, an annual average concentration of 400 Bq/m3 applicable for existing dwellings; and design levels of an annual concentration of 200 for future construction, above which remedial actions and preventive measures should be considered.
In addition to reference levels for indoor radon concentration in workplaces (1000 Bq/m3) and dwellings and buildings with public access (300 Bq/m3 for existing, 200 Bq/m3 for new ones), the Euratom Basic Safety Standards foresees obligating EU Members to establish a radon action plan, aimed at managing long-term risks of radon exposures in dwellings, buildings with public access and workplaces for any source of radon ingress, whether from soil, building materials or water. JRC has prepared a map on indoor radon concentration and is currently trying to produce a European geogenic radon map.
A geogenic map has been produced and a first trial version was presented at the 11th International Workshop on the Geological Aspects of Radon Risk Mapping held in Prague in 2012. After that the JRC has created a more comprehensive geogenic radon database asking the participating countries to supply radiometric data related to radon. Nowadays, the range and distribution of indoor radon levels in other countries, such as the US, have been quantified and scientifically measured by national surveys.
Don’t worry. You can still rent a house for your holidays even abroad. The risk from radon is on the basis of a lifetime spent in the same house. Some experts argue that small doses of radiation may even be good for us, stimulating our immune defences. But if they invite you to try, politely decline: “I am trying to give up smoking. Radon, at least”.