Knowing whether or not to install a radon mitigation system is a good thing. Not knowing? Let's just say that's unacceptable. Many tests are anticipated with a bit of anxiety, causing people to procrastinate and put them off, but a radon test shouldn't be one of them. It is, in fact, the only way to know for sure that mitigation is necessary. If you test your home for radon gas levels and find all is well, that's great. You're good to go. If your test results indicate high levels of this dangerous radioactive gas, it's still great. You know there are steps you should take to protect those who breathe the contaminated air. Either way, knowing the radon level in your home is a good thing.
Radon, an odorless, colorless, tasteless gas, is the leading cause of lung cancer in non-smokers. It is second only to smoking as the source of the disease. It is possible to temporarily reduce radon levels by simply opening doors, windows, and vents on lower floors of your home, but that should not be used as a long-term mediation strategy. This type of ventilation sees values return to their previous levels in just 12 hours. That's not good enough.
Test results indicate the need for mitigation
Measured in units expressed as picocuries of radon per liter of air, or pCI/L, The U.S. Congress recently set a goal to lower indoor levels in the country to that of outdoor levels, a rather ambitious 0.4 pCi/L. The U.S. Environmental Protection Agency advises mediation if your long-term test, or two short-term tests, return results measuring 4 pCI/L or more.
Radon mitigation methods
Foundation type and mitigation choice
Homes with basements or slab foundations are usually mitigated with suction systems. In a passive suction system, pipes are inserted into the rock and soil below, either from the floor slab or from outside the home. The radon test results indicate how many pipes will be needed and where they should be located. It is often the case that just one pipe is required to achieve a recommended level.
Active suction systems connect pipes like those described above to a vent fan located outside the house or in an unconditioned area like a garage or attic space. The fan draws the gas from below the home and releases it into the outdoor environment, creating a vacuum under the slab.
Homes with basements may have block wall suction systems that make use of the hollow areas in the block foundation walls, effectively depressurizing them and directing the gas to outdoor release.
Homes with crawlspaces can be fitted with a high-density plastic sheet that covers the earth beneath the home. A pipe below the sheet vents to the outdoors, directing the gas out of the home. These radon mitigation systems can be fitted with a fan to create a stronger vacuum. Some homes achieve adequate reduction of levels simply by ventilating the crawlspace, either passively, or actively with the use of a fan.
While not a stand alone method, sealing reinforces the effectiveness of other mitigation systems, limiting the flow of radon into the home. As foundations settle, soil moves, and cracks form, new openings may occur in a previously sealed foundation, again allowing dangerous levels of radon gas to accumulate in the indoor environment.
Heat Recovery Ventilator
Also called an air-to-air heat exchanger, this system relies on increased ventilation to reduce radon levels. Most effective when used in basements, these systems require a proper balance to reduce the levels, but can be helpful in reducing other indoor air contaminants as well. This system may, however, result in significant energy use for heating and cooling.
This system relies on a fan blowing air from upstairs or outdoors into the lowest level of the home. Doors and windows on the lower level must be closed as much as possible. Introducing moisture and temperature challenges, this method may prove costly by comparison, depending on the layout, construction, and radon levels of the home.
Water treatment at point-of-entry
Posing much less of a risk than airborne radon gas, water could be responsible for some of the radon concentration in a home from showering, drinking, or running the tap. Wells, springs, and underground water sources are much more likely than surface water sources to carry radon into the home, and therefore should be tested. Mitigation for the water supply at the point-of-entry is the recommended treatment, using a granular activated carbon filter or aeration system.
Costs associated with radon mitigation
Suction and depressurization radon mitigation systems typically run anywhere from $500 to $2,000, with some more challenging fixes priced at between $3,000 to $5,000. The typical radon reduction seen with these systems ranges from 50 to 99 percent, with passive subslab systems sometimes a less effective choice that also results in increased energy costs.
Considering the alternatives, these costs pale in comparison to the costs of the associated disease. Additionally, the peace of mind that comes with knowing your loved ones are safe is priceless.
- The effectiveness of mitigation for reducing radon risk in single-family Minnesota homes. Steck DJ. 2012. http://www.ncbi.nlm.nih.gov/pubmed/22850228
- The cost effectiveness of radon mitigation in existing German dwellings -- a decision theoretic analysis. Haucke F. 2010. http://www.ncbi.nlm.nih.gov/pubmed/20619957
- Radon Reduction Methods -- A Homeowners Guide (PM-1350) Iowa State University College of Engineering and the College of Agriculture and Life Sciences. 1995. http://www.abe.iastate.edu/extension-and-outreach/radon-reduction-methods-a-homeowners-guide/
- EPA Consumer's Guide To Radon Reduction: How to fix your home. 2003. http://www.cpe.rutgers.edu/CT-Radon/downloads/Consumers-Guide-to-Radon-Reduction.pdf