Minimizing the Risks of Radon in the Home

Radon is a natural radioactive gas that emanates from the ground into the air. It has no odor, color or taste. Radon is produced from radium during the decay of uranium, an element found in varying amounts in all rocks and soil. Radon gas escapes easily from the ground into the air and emits radiation called alpha particles. These particles are electrically charged and attach to aerosols, dust and other particles in the air we breathe. They can be deposited on the cells lining human airways, where the alpha particles can damage the DNA and potentially cause lung cancer.

Radon gas in the air is present worldwide, its concentration depending on the highly variable uranium content of the soil. It is the second most important risk factor for lung cancer, causing between 6% and 15% of all cases. On a global level, tens of thousands of lung cancer deaths annually can be attributed to radon. Although the average exposure to radon varies enormously, recent studies have shown that, when exposed to radon, those who smoke have a much higher risk of lung cancer than non-smokers. Most of the radon-induced lung cancer cases occur among smokers, but radon is also the leading cause of lung cancer for non-smokers.

Yet there is little public awareness of radon as a threat to human health that can be mitigated with relatively simple measures.

According to the National Academy of Sciences and the US Environmental Protection Agency (EPA), 20,000 people die every year in the United States due to lung cancer from exposure to radon in their homes. The science on radon is among the strongest for any environmental contaminant.

Studies Find Direct Evidence Linking Radon in Homes to Lung Cancer
The EPA notes that two recently published studies show definitive evidence of an association between residential radon exposure and lung cancer. Both studies, one in North America and one in Europe, combined data from several previous residential studies. These two new studies confirm the radon health risks predicted by occupational studies of underground miners who breathed radon for a period of years.

Early in the debate about radon-related risks, some researchers questioned whether occupational studies could be used to calculate risks from exposure to radon in the home environment. "These findings effectively end any doubts about the risks to Americans of having radon in their homes," said Tom Kelly, Director of EPA's Indoor Environments Division. "We know that radon is a carcinogen. This research confirms that breathing low levels of radon can lead to lung cancer."

WHO International Radon Project
In an effort to reduce the rate of lung cancer around the world, the World Health Organization (WHO) is launching the International Radon Project to help countries reduce the health risks associated with radon gas. The project will identify effective strategies for reducing the health impact of radon, promote sound policy options for countries and increase public and political awareness about the consequences of exposure to radon.

"Radon poses an easily reducible health risk to populations all over the world, but has not up to now received widespread attention," said Dr. Mike Repacholi, coordinator of WHO's Radiation and Environmental Health Unit. "Radon is all around us. Radon in our homes is the main source of exposure to ionizing radiation, and accounts for 50% of the public's exposure to naturally-occurring sources of radiation in many countries."

Due to dilution in the air, outdoor radon levels are usually very low. Radon can also be found in drinking water, the concentration depending on the water source, and this can sometimes present a hazard. Radon levels are higher indoors, and much higher radon concentrations can be found in places such as mines, caves and water treatment facilities, and an increased lung cancer risk has been found in uranium miners. For the average citizen, by far the greatest exposure to radon comes in the home.

The concentration of radon in a home depends on the amount of uranium producing the radon in the underlying rocks and soils as well as the routes available for its passage into the home and the rate of exchange between indoor and outdoor air. Radon gas enters houses through openings such as cracks at concrete floor-wall junctions, gaps in the floor, small pores in hollow-block walls, and also sumps and drains. Consequently, radon levels are usually higher in basements, cellars or other structural areas in contact with soil, and the radon concentrations in houses directly adjacent to each other can be very different.

Radon exposure in homes can be easily mitigated during the construction of new homes, but existing buildings can also be protected from radon. Most measures such as increasing under-floor ventilation and sealing cracks and gaps in the floor require simple alterations to the building, but other approaches may have to be taken in areas with high radon concentrations. Overall, reducing radon exposure is an important contribution to the goal of good quality indoor air.

Test Household Air for Radon
According to EPA estimates, one in every 15 homes nationwide has a high radon level at or above the recommended radon action level.

US Surgeon General Richard H. Carmona noted, in a National Health Advisory On Radon, "Indoor radon is the second-leading cause of lung cancer in the United States and breathing it over prolonged periods can present a significant health risk to families all over the county. "

Uncomplicated test kits can reveal the amount of radon in any building. Those with high levels "can be fixed with simple and affordable venting techniques," notes the Wisconsin Department of Natural Resources, adding that radon air test kits typically cost from $15 to $30 and are available at most hardware stores. Test kits should display the phrase "Meets EPA Requirements."

The WHO International Radon Project is initially expected to run for three years (2005-2007). The first step will involve setting up a global network of radon scientists, regulators and policy makers to collaborate in the project. Working groups will focus on risk assessment, exposure guidelines, measurement and mitigation of radon levels, investigations of cost-effectiveness and risk communication. WHO guidelines based on this work will help national authorities to develop, promote and strengthen activities at country or regional level.

The WHO International Radon Project also aims to create a global radon database and provide improved global estimates of the disease burden associated with radon worldwide. Overall, together with global tobacco control activities and initiatives on healthy indoor air, the Project is expected to be a key step toward reducing lung cancer risk worldwide.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.