Characteristics of Radon-222

Fate and Transport

Monitoring in the Environment


Measurement Methods

Control and Prevention

Harmful Effects

Absorption, Distribution and Organic Sites of Toxicity

Radon Dose

Radon Biomarkers

Risk Assessment

Molecular Action and Genetic Effects

Radon for Skeptics

Radon for Children

Strategies for Preventing or Controlling Exposure

Preventing and Controlling Radon

  • A variety of methods can be used to reduce radon in homes and buildings.
  • The EPA recommends reducing levels to 4 pCi/L or less.
  • Radon exposure can come from both water and soil/rock

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=suction device
slab-on-grade (concrete poured at ground level)=suction device
crawlspace (shallow unfinished space under 1st floor)=ventilation

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 can range from $800 to about $2,500.

In houses that have a basement or a slab-on-grade foundation, radon is usually reduced by one of four types of soil suction: subslab suction, drain tile suction, sump hole suction, or block wall suction.
Active Subslab suction (also called subslab depressurization) is the most common and usually the most reliable radon reduction method. Suction pipes are inserted through the floor slab into the crushed rock or soil underneath. They also may be inserted below the concrete slab from outside the house. Passive subslab suction is the same as active subslab suction except it relies on air currents instead of a fan to draw radon up from below the house. Passive subslab suction is generally not as effective in reducing high radon levels as active subslab suction.
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 basement houses with hollow block foundation walls. This method removes radon from the hollow spaces within the basement's concrete block wall.

Crawlspace Houses

In houses with crawlspaces, radon levels can sometimes be lowered by ventilating the crawlspace passively (without the use of a fan) or actively (with the use of a fan). Crawlspace ventilation lowers indoor radon levels both by reducing the home's suction on the soil and by diluting the radon beneath the house. Natural ventilation in a crawlspace is achieved by opening vents, or installing additional vents. Active ventilation uses a fan to blow air through the crawlspace instead of relying on natural air circulation.

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 either temporary measures, or only partial solutions to be used in combination with other measures.

Sealing cracks and other openings in the foundation is a basic part of most approaches to radon reduction. Sealing does two things, it limits the flow of radon into your home and it reduces the loss of conditioned air, thereby making other radon reduction techniques more effective and cost-efficient. It is difficult to identify and permanently seal the places where radon is entering.

House pressurization uses a fan to blow air into the basement or living area from either upstairs or outdoors. The effectiveness of this technique is limited by house construction, climate, other appliances in the house, and occupant lifestyle. In order to maintain enough pressure to keep radon out, the doors and windows at the lowest level must not be left opened, except for normal entry and exit.

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 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, and security concerns.

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.

Radon in Water Supply

  • If you’ve tested for radon entering your home in air and have elevated radon levels and your water comes from a private well, have your water tested.
  • Most of your risk from radon in water comes from radon released into the air when water is used for showering and other household purposes.
  • A radon in water problem is more likely when its source is ground water, e.g. a private well or a public water supply system that uses groundwater. Some public water systems treat their water to reduce radon levels before it is delivered to your home.
  • If you’ve tested your private well and have a radon in water problem, it can be fixed in two ways:

1) Point of entry treatment removes radon from the water before it reaches your home; granular activated carbon (GAC) filters or aeration devices are used. While GAC filters usually cost less than aeration devices, filters can collect radioactivity and may require a special method of disposal.

2) Point of use treatment devices remove radon from your water at the tap, but only treat a small portion of the water you use, e.g. the water your drink. Point of use devices are not effective in reducing the risk from breathing radon released into the air from all water used in the home.

Post-Mitigation Testing

  • To ensure continued effectiveness of the radon mitigation system installed, the client should retest the building at least every two years or as required or recommended by state or local authority.
  • Retesting is also recommended if the building undergoes significant alteration.

Finding a Mitigation Contractor

  • Get more than one estimate and check your contactor’s references.
  • Any contracting work must conform to state regulations.
  • It’s best to check radon levels again after work has completed.
  • Find a Qualified Radon Service Professional: http://www.epa.gov/iaq/radon/proficiency.html


1.) EPA Radiation Information – Radon

2.) EPA Indoor Air Information – Radon

3.) Minnesota Dept of Health - Radon

4.) The Minnesota Radon Project

5.) Radon Occurence and Health Risk

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