Radon

EPA Standards on Radon

In 1986, the EPA recommended all homes be tested for radon, and in 1988, the U.S, Congress enacted the Indoor Radon Abatement Act, which set a national goal to reduce radon in buildings to the ambient level of outdoor air. As a result, the EPA set an action level of 4.0 picocuries per liter (pCi/L) for indoor radon. If radon is found above 4.0 pCi/L, the EPA recommends homeowners install mitigation equipment. There is still some risk at levels below 4.0 pCi/L, and the EPA suggests that indoor radon levels are as close to ambient outside air as possible (outside air has approximately 0.4 pCi/L).

Radon Health Effects

Radon is a known human carcinogen. It breaks down into radioactive particles that can damage lung cells and increase the risk of lung cancer. According to the EPA, radon is the leading cause of lung cancer [external link] among non-smokers causing an estimated 21,000 lung cancer deaths in the U.S. each year. The Iowa Radon Lung Cancer Study [external link] tracked nearly 1,000 women who had lived in their homes more than 20 years. The results of the case-control study (after adjusting for age, smoking, and other factors) indicated that a 20-year exposure of radon levels at the EPA guideline of 4.0 pCi/L yielded an increased lung cancer risk of 50%.

Cigarette smoking and radon exposure produce a synergistic effect. In fact, people who smoke who are exposed to high concentrations of radon, have an estimated 10 to 15 times greater risk of developing lung cancer than non-smokers. 

Radon Mitigation

High levels of radon can be easily remedied. If your home has elevated levels of radon above the EPA’s recommended action level of 4.0 picocuries of radon per liter of air (pCi/L), a radon mitigation system should be installed. Radon levels less than 4.0 pCi/L still pose a risk, and in many cases can be reduced. Repairs usually cost no more than many other common home repairs (ranging from $800 - $1,200) and will not change the appearance of your home.

Mitigation Methods

Methods of mitigation depend on the type of foundation your home has and differ for basements, crawl spaces, engineered floors, slab on grade or any combination of these foundations. Radon mitigation can be accomplished by mitigating one or more of the following factors:

• Sources of radon in the soil, building material or well water
• Transport mechanisms that drive radon into a building, usually pressure differentials
• Radon entry pathways that allow radon to enter a structure, usually cracks or openings in the foundation, or open crawlspaces
• Accumulation of radon and RDPs in the building

Active Soil Depressurization

Of these, controlling radon transport by pressure-driven entry is the most common mitigation technique used in Colorado. This is called Active Soil Depressurization (ASD). This technique creates a suction or area of low pressure beneath the structure that is stronger than the partial vacuum applied to the soil by the building. ASD systems consist of pipes connected to a fan, which draws gasses from under the building. Radon is captured and vented to the outside before it has a chance to enter the home. Several types of ASD systems exist including:

• Sub-slab depressurization systems
• Drain tile depressurization systems
• Sub-membrane depressurization systems
• Block-wall depressurization systems
• A combination of the above methods

Hiring a Contractor

All of these ASD systems require expert installation, additional sealing of openings into the home, and of course, testing to verify that radon levels have been reduced to below 4 pCi/L. If you wish to hire a contractor, please visit CDPHE [external link] for more information on finding a certified radon mitigation contractor who is trained in proper and effective radon mitigation. 

Tips for hiring a contractor include:

• Ensure the contract stipulates that the contractor will follow all EPA protocols regarding radon mitigation and will obtain all applicable local permits.
• Get bids from multiple contractors.
• Obtain a guarantee that radon levels will be reduced to 4.0 pCi/L or below.

Doing Your Own Mitigation

If you decide to mitigate yourself, information about mitigation system installation and design is available in the manual “Protecting Your Home from Radon: A Step-by-Step Manual for Radon Reduction” by Douglas L. Kladder and Associates. This manual is available in all Colorado public libraries and is also available at JCPH.

Radon in Schools

Schools and childcares are at risk from radon just like homes. The state of Colorado requires all schools and childcares to test for radon and to maintain records of the test results for disclosure upon request. The statute does not require schools or childcares to mitigate radon. If radon mitigation is needed, the school district and its constituents must address mitigation issues. For more information, visit Rules and Regulations Governing School in the State of Colorado [external link] and Rules and Regulations Governing Health and Sanitation in Child Care Facilities (PDF).

Radon in Water

Soil gas is the largest natural source of radon in homes; however, well water can be a significant factor if high concentrations of dissolved radon are found. In 1992, the EPA proposed a maximum contaminant level (MCL) of 300 pCi/L for public water supplies. As a result of these proposed MCLs, radon may become the most common treated-for contaminant in well water. In Colorado, radon in well water averages well above the proposed MCL.

High radon levels in water are required to significantly elevate radon in air. The EPA uses a "rule of thumb" of 1:10,000. That is, if you have 10,000 pCi/L of radon in water, indoor radon concentrations might increase by 1 pCi/L. Recent studies indicate that elevated radon levels in water are an inhalation threat and may be an ingestion hazard, increasing the risk of stomach cancer.

Treatment for Radon in Water

There are three recognized treatment methods to remove radon from water:

• Storage of the water until the radon decays
• Aeration to strip the radon from the water
• Granular activated carbon filter

Storing Water

Storing water until the radon decays is somewhat impractical because it takes 27 days for 99% of the radon to decay. A typical family of four using 300 gallons of water per day would need 8,100 gallons of storage. A tank this large is impractical and expensive.

Aeration

Aeration is the preferred method for treating radon in water. As the water is aerated, radon is released and piped outside. This method requires another pump to pressurize the pressure tank, a radon fan and biological treatment of the aerated water because it may be contaminated by the air used for aeration.

Granular Activated Carbon

Granular activated carbon (GAC) removes radon in water by adsorbing the radon onto the carbon; however, gamma radiation results from the radon decay products (RDPs) that accumulate in the filter. To prevent radiation hazards to the occupants, the filter must be shielded or remotely located.

Testing for Radon

Testing for radon is simple and inexpensive. Any home can have a radon problem including apartments. Jefferson County Public Health offers radon test kits for only $10. Call 303-271-5700. Long-term test kits are also available at local hardware stores, supermarkets and other retail outlets. 

If you have questions or need more information on radon, radon testing and radon mitigation, contact Public Health.