The World Health Organization (WHO) Handbook on Indoor Radon

On September 21, 2009, the World Health Organization (WHO) released a guidance document on radon risks titled: WHO Handbook on Indoor Radon - A Public Health Perspective. This summary is intended to clarify our understanding of the WHO "Handbook" and to help you communicate with your customers and to separate fact from fiction.

Since the launch of the Handbook, there have been press releases, news articles, and Internet blogs that have been circulating around the US. Many of the stories are written by individuals who do not fully understand the intent of the Handbook, which has led to the inaccurate statements. The most popular rumor circulating within the real estate community is that the 4.0 pCi/L radon Action Level, set by the US Environmental Protection Agency's (EPA), has been lowered to 2.7 pCi/L by the World Health Organization. This rumor is untrue. The US Action Level has not been changed and is still 4.0 pCi/L.

The WHO working group on radon was primarily made up of scientists and health experts, which were focusing on lung cancer statistics and health implications of radon exposure with hopes of bringing more attention to the adverse health effects of prolonged radon exposure. They also set goals for maximum radon exposure that will become useful to policymakers around the world working to develop and strengthen radon programs in countries around the world. In reality, the WHO position reinforces EPA's longstanding guidance that homeowners should consider fixing their homes when the indoor radon level is between 2 and 4 pCi/L; since there is significant risk at levels below 4 pCi/L and no known "safe" level of radon exposure. EPA believes that many homes can be reduced to below 2 pCi/L.

Updates on EPA's radon program, can be obtained from their website:

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