While EPA guidelines focus on radon ranges above 4 pCi/L, homeowners may want to take action even if test results are in the 2-4 pCi/L range. Homeowners have a variety of options when it comes to reducing or mitigating radon levels. Deciding on the level of monitoring required, disruption to home and property, and cost is a good first step.
Two Approaches to Mitigation
There are two ways to reduce the radon in a house:
- Prevent the gas from getting in.
- Vent the gas to lower the concentration.
The methods used and costs involved depend on the radon level, construction of the home, and characteristics of the underlying soil. Costs can vary from $200 to $2,500 with some methods requiring annual operating costs and increased heating or air conditioning bills.
- The simplest way to keep radon out is to seal the openings through which it enters. Gaps around utility pipes and cracks in basement floors and between the basement floor and walls are easy to seal with minimally expanding foam. However, smaller cracks may be difficult to identify. Sealers also age and crack, and the normal settling of a house tends to open new cracks and reopen old ones. For those reasons, the EPA says sealing alone does not lower radon levels significantly or consistently but works best when used with other methods.
- Another simple approach is to just open windows and doors. This mixes outdoor air with indoor air and reduces radon concentrations. However, the fix is only temporary. Once doors and windows are closed, radon concentrations often return to earlier levels in less than a day. It also can mean a loss of heated or cooled air, increased energy costs, and security concerns.
- Providing proper air intake and exhaust for combustion appliances is another way to prevent radon penetration. It eliminates the negative air pressure created when furnaces and clothes dryers use indoor air, creating suction that draws radon into the home.
More Involved Solutions
There are several active methods to prevent radon from entering the home or to dilute its concentration. A house may combine more than one approach to attain a lowered radon reading.
|House/room pressurization. With this method, a fan blows air into the basement from either upstairs or outdoors to create enough basement air pressure to prevent radon from entering. To keep that pressure, doors and windows at the lowest level should remain closed except for normal entry and exit. With this method, more outdoor air enters to dilute interior air, but along with it comes increased moisture.|
|Forced ventilation. This method is similar to house/room ventilation. It uses fans to increase a home’s natural air exchange by drawing air into the house. As the existing indoor air leaves the house through vents or open windows, it takes the radon with it. Heat loss can be a problem during cold weather, so this technique should be considered carefully. A heat-recovery ventilator, or air-to-air heat exchanger, is an option. It uses exhausted air to warm or cool incoming air. A heat exchanger is most effective for basement use. It must be properly maintained and can add to energy costs.|
|Sub-slab depressurization. This approach is the most common method for radon mitigation. It generally runs $1,000-$1,500, depending on the local market, how complicated it is to run the pipe(s), and makeup of the underlying soil.
The system involves:
A passive system may also be used, relying on natural pressure differences and air currents to draw radon up the pipe and out of the house. The passive system, however, is not considered as effective.
|Drain-tile suction. This technique uses a continuous loop of perforated tiles around the house perimeter. It can work with an existing drain-tile system to keep water away from the foundation. An exhaust fan is hooked up to the system and the suction created pulls radon away from soil around the house. Sump-hole suction, where the sump pump is capped and serves as the site for a radon-suction pipe, is another option.|
|Crawlspace ventilation. Homes with crawlspaces require additional methods. One is to cover exposed soil in the crawlspace with a barrier, such as concrete or polyethylene. It also may be necessary to vent the radon from under the barrier by pipe and fan to the outdoors. Another option is to use vents in the crawlspace to allow outdoor air to enter or use a fan to blow air across the crawlspace. In cold climates, venting may require insulating affected water lines.|
Research Radon Contractors
Homeowners should consult with a radon specialist about the best mitigation method for their home. Since the EPA closed its proficiency program in 1998, however, there has been no federal certification available. Some states have their own certification programs and others have lists of qualified mitigation specialists. Several states require providers to be licensed or registered. State radon offices can be located at the EPA website.
Two independent groups—the National Environmental Health Association (radon.org) and the National Radon Safety Board (nrsb.org) offer national certification programs.
Always check references to avoid a ineffectual or dangerous repair. Michael Murphy, health physicist for Region 5 of the EPA, says he has heard about horrendous fixes by unqualified contractors. In one case a dryer-vent hose, which could be easily torn, was used in place of the schedule 40 PVC pipe.
Retest after Mitigation
After remediation, test to see if the system is working. The test should be conducted within 30 days, but no sooner than 24 hours, after installation to give the system a chance to work. While the contractor may perform a post-mitigation test, a homeowner may want an independent follow-up test.
A two- to seven-day measurement is recommended. Contractors may provide a guarantee to adjust or modify the system to reach a negotiated radon level. Retesting every two years will indicate whether a system is still working effectively.
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