GETM

Indoor Air Quality-RADON (Rn)

Author addresses issues of Radon gas, its impact on human health, and mitigation measures. Review by Pushpa Tuppad & Devanand Maski

January being the National Radon Action Month, its time to refresh the awareness related to the issues of Radon in the environment. Here is a brief review of Radon, indoor Radon concentrations, its impact on human health, and mitigation measures.

Smoking, Radon, and passive (secondhand) smoke are the leading causes of lung cancer. Association of smoking with lung cancer and deaths are widely known facts but Radon as a leading cause of lung cancer in non-smokers and second only to smoking in smokers is a less known fact. Because exposure to high levels of Radon is preventable, there is a pressing need to create awareness in public about health effects of Radon, test homes and schools for Radon concentrations and take necessary actions.

Radon (Rn) is a radioactive inert gas, produced as a decay product of Uranium. Radon has a half-life of 4 days. Uranium occurs naturally in the earth’s crust and continuously undergoes radioactive decay releasing Radon along the way. Being a gas, Radon eventually finds its way up through the soil surface and into the atmosphere. The average background Radon concentration outdoors is 0.4 Pico curies per liter (pCi/l) of air. Radon enters the buildings primarily through the floor (foundation cracks and openings) and builds up in concentration indoors depending on the design of the house, local geology, soil conditions, and weather.

Radon, as such, is not harmful to humans. However, being a radioactive gas emits alpha particles, further decays to Polonium, and eventually to stable Lead. Lead gets deposited onto the indoor air and dust particles, which then eventually enter the lungs when inhaled. Alpha radiation causes damage to sensitive lung tissues. Rather than Radon itself, its decay products further decay quickly producing radionuclides that damage lung tissue.

The U.S Environmental Protection Agency (EPA) indoor air quality standards require the Radon concentrations not to exceed 4 pCi/L of air. To learn more about Radon, please visit the EPA website http://www.epa.gov/Radon

Radon easily dissolves in water and is found in drinking water where groundwater is the primary drinking water source. Because of its gaseous nature, dissolved Radon easily escapes into air when water is agitated or stirred. Radon in water is not a major health concern because alpha particles emitted by Radon and its decay products in water readily lose their energy and are taken up by other compounds in water.

The first and foremost step, after knowing about Radon and its associated hazards, is to test homes and other sensitive indoor buildings to Radon levels. EPA and the Surgeon General recommend testing for Radon in all rooms below the third floor. EPA recommends testing for Radon in schools. Radon testing can be done using low-cost “do-it-yourself” Radon test kits or through certified Radon professionals. If found in concentrations exceeding 4 pCi/L, the next step will be to take measures to reduce it. The typical mitigation system, which is relatively inexpensive, usually has a pipe through the basement floor to the outside of the building. The pipe may also be installed outside the building. A small exhaust fan in the pipe enhances the suction to expel Radon from the floor underground to outside air.

Taking action regarding indoor Radon is purely on a voluntary basis. Just knowing that Radon is carcinogenic, occurs naturally and is the cause of an estimated 21,000 deaths {according to EPA’s 2003 Assessment of Risks from Radon in Homes (EPA 402-R-03-003, http://www.epa.gov/Radon/risk_assessment.html)}, should encourage people to take actions to protect from its dangers. The low cost of treatment makes it a very worthwhile investment.

A detailed document about protection from Radon can be found at http://www.epa.gov/Radon/pubs/citguide.html

Posted by Moderator on January 10th, 2006 filed in review Discuss now »