Strategies for Preventing or Controlling Exposure

Housing Types and Specific Reduction Methods
Other Types of Radon Mitigation
Post-Mitigation Testing

Preventing and Controlling Radon

A variety of methods can be used to reduce radon in homes and buildings.
The IEMA Radon Program recommends reducing levels to the lowest level achievable.
Mitigation can also decrease moisture and other soil gases entering the home, reducing the potential for mold, mildew, methane, pesticide gases and other air quality problems.

Housing Types and Specific Reduction Methods

Your house type will affect the kind of radon reduction system that will work best. Houses are generally categorized according to their foundation design.

-Types of housing foundations and method necessary:
basement=sub slab depressurization
slab-on-grade (concrete poured at ground level)=sub slab depressurization
crawlspace (shallow unfinished space under 1st floor)=sub membrane depressurization

Basement and Slab-on-Grade Houses

These systems prevent radon gas from entering the home from below. The average cost for a contractor to lower radon levels in a home usually ranges from $700 to about $1,500. Houses with crawl spaces and/or other unusual construction features that take more material and labor can cost more. In houses that have a basement or a slab-on-grade foundation, radon is usually reduced by one of three types of soil suction: subslab suction, drain tile suction, or block wall suction.
Active Subslab suction (also called subslab depressurization) is the most common and the most reliable radon reduction method. Suction pipes are inserted through the floor slab into the crushed rock or soil underneath.

Some houses have drain tiles to direct water away from the foundation of the house. Suction on these drain tiles is often effective in reducing radon levels if the drain tiles form a complete loop around the foundation.
Block wall suction can be used in houses with basements that have hollow block foundation walls. This method removes radon from the hollow spaces within the basement's concrete block wall.

Crawlspace Houses

"Sub-Membrane Depressurization (SMD)" means a radon control technique designed to achieve lower air pressure in the space under a soil gas retarder membrane laid on the crawlspace floor, relative to air pressure in the crawlspace, by use of a fan-powered vent drawing air from beneath the membrane.

Other Types of Radon Mitigation

Other methods to Reduce Radon in Your Home

Sealing cracks
House pressurization Natural ventilation
Heat recovery ventilation

Most of these methods are considered to be temporary measures, or only partial solutions to be used in combination with other measures.

Sealing cracks and other openings in the foundation and concrete floors is a basic part of approaches to radon reduction. Sealing does two things; it limits the flow of radon into your home thereby making other radon reduction techniques more effective and cost-efficient. More importantly, sealing stops conditioned air (heated and air conditioned) from being pulled out of the home by the radon reduction systems - saving hundreds of dollars per year in energy cost.

Some natural ventilation occurs in all houses. By opening windows, doors, and vents on the lower floors you increase the ventilation in your house. This increase in ventilation mixes radon with outside air and can result in reduced or increased radon levels. Natural ventilation in any type of house should normally be regarded as a temporary radon reduction approach because of the following disadvantages: loss of conditioned air and related discomfort, greatly increased costs of conditioning additional outside air, security concerns, and usually not effective.

A heat recovery ventilator (HRV), also called an air-to-air heat exchanger, can be installed to increase ventilation. An HRV will increase house ventilation while using the heated or cooled air being exhausted to warm or cool the incoming air. However this is the most expensive option and will only reduce the radon a few pCi/L.

Post-Mitigation Testing

IEMA Radon Program Rules state that post Mitigation measurement(s) shall be conducted to determine a system's effectivemenss after a permanent radon reduction system has been fully operational for at least 24 hours but not later than 30 days following completion and activation of a mitigation system. The mitigation system shall be operated normally and continuously during the entire measurement period.

To ensure continued effectiveness of the radon mitigation system installed, the client should retest the building at least every two years as recommended by the IEMA Radon Program.
Retesting is also recommended if the building undergoes significant alteration.