Radon is a colorless, tasteless, odorless, radioactive gas. It is a product of the natural decay of radium, which itself is a product of uranium, and is found in soils and rocks such as granite and shale. Radon is the heaviest of the noble gases and is chemically inert. However, when radon undergoes radioactive decay those subsequent electrically charged particles become attached to dust, which can then be inhaled into the lungs. According to the EPA, radon is the leading cause of lung cancer among non-smokers and the second leading cause of lung cancer in the United States, claiming 20,000 lives annually.
Uranium is found in varying amounts throughout the earth’s crust and radon is continually being formed. The EPA has created a map of radon zones so that one may determine the risk in a particular area. Radon is not a hazard outdoors as it is quickly diluted to safe levels by the outside air. It poses a health risk only when it builds up inside an enclosed space. This is a particular concern in basements and ground floor rooms where the gas becomes trapped after percolating up through porous soils and entering the building through small cracks in the foundation, insulation, pipes, and drains.
Radon in Water:
Radon can be present in groundwater that has been in contact with radium-containing rock and is the second most prominent source of environmental radon. Groundwater contaminated with radon is a concern because radon is only minimally soluble in water. When a contaminated aquifer is the source for a water supply it can release radon into the air through showers, washing machines, and dishwashers. The risks associated with drinking radon are much lower than those associated with inhaling it. The concentrations found in groundwater are highly variable and depend on such factors as the distribution of the aquifer relative to the rock, groundwater flow patterns, and the uranium content of the rock. Private wells are much more likely to contain unsafe levels of radon than public water systems.
The levels of indoor radon and radon in water are easy (if not quick) to determine. This can be accomplished using a “do-it-yourself” radon test kit that has passed EPA’s testing program or by hiring a contractor certified by the National Radon Safety Board or the National Environmental Health Association. Indoor radon tests typically fall into two categories: short-term and long-term. Radon levels vary dramatically throughout the seasons (sometimes even during short weather events) therefore the Navy’s Radon Assessment and Mitigation Plan (NAVRAMP) recommends that long term tests of more than 120 days be used for initial screening of a particular area. Short term tests with an exposure of 2 to 90 days may be used for follow-up measurements.
Reducing Radon Levels:
Radon is typically measured in picocuries per liter [pCi/L]. A curie is a measure of the intensity of radioactivity and is based on the radioactivity of one gram of radium. Indoor radon levels can be controlled by implementing certain radon-reducing construction techniques. Guidelines for new buildings are posted on the EPA’s website and the DoD has is released its own set of building requirements. In existing structures found to have unsafe levels of radon (concentrations ≥4 pCi/L) NAVRAMP requires that action be taken:
• 0-4 pCi/L no mitigation required
• 4-20 pCi/L mitigate within 5 years
• 20-200 pCi/L mitigate within 6 months
• ≥ 200 pCi/L mitigate within 3 weeks.
Radon can be reduced through passive mitigation (such as sealing cracks in floors) and active forms of mitigation (such as subslab depressurization and submembrane depressurization). Mitigation systems should be inspected every 2 years.
There are several ways to reduce radon in water. A very effective method is through aeration such as a spray, bubble, and packed-tower systems. Homeowners may use a point-of-entry device that treats water where it enters the home. Point-of-use devices (generally installed on a tap) are also available, although they only remove radon from the water at that point and do not reduce the risk due to inhalation.
Toxic Substances Control Act (TSCA) Title III: Indoor Air Radon Abatement
DoD 6025.18: Dept. of Defense Health Information Privacy Regulation (Jan. 2003)
NAVRAMP: Navy Radon Assessment and Mitigation Program (Sept. 2003)
OPNAVINST 5090.1C Chapter 30: Radon Assessment & Mitigation (Oct. 2007)
MCO P5090.2A: Environmental Compliance and Protection Manual (Paragraph 6206)
Public Law (PL) 100-551 (102 Stat. 2755): Indoor Radon Abatement Act 1988
UFC 3-490-04A Design: Indoor Radon Prevention and Mitigation (May 2003)
Contact 401-841-7672 for assistance.