If the Radon level is above is 4 pCi/L or more fix your home. There are several methods, ways to mitigate, and lower the radon levels in your home. Some techniques prevent radon from entering your home while others reduce radon levels after it has entered. Your house type will affect the kind of radon mitigation system that will work best. Houses are generally categorized according to their foundation design such as basement, slab-on grade (concrete poured at ground level), or crawlspace (a shallow unfinished space under the first floor). Some houses have more than one foundation design feature. In these situations a combination of radon reduction techniques may be needed to reduce radon levels.

In Basement and Slab-on-Grade Houses, radon is usually reduced by one of four types of soil suction: sub-slab suction, drain tile suction, sump hole suction, or block wall suction:

• Active sub-slab suction (also called sub-slab depressurization) is the most common and usually the most reliable radon reduction method. One or more suction pipes are inserted through the fl oor slab into the crushed rock or soil underneath through the house thru the roof. They also may be inserted below the concrete slab from outside the house. The number and location of suction pipes that are needed depends on how easily air can move in the crushed rock or soil under the slab, and on the strength of the radon source. Often, only a single suction point is needed. A radon vent fan connected to the suction pipe(s) draws the radon gas from below the house and releases it into the outdoor air while simultaneously creating a negative pressure (vacuum) beneath the slab. Common fan locations include unconditioned house and garage spaces, including attics, and the exterior of the house.
• Passive sub-slab suction is the same as active sub-slab suction except it relies on natural pressure differentials and air currents instead of a fan to draw radon up from below the house. Passive sub-slab suction is usually associated with radon resistant features installed in newly constructed homes. Passive sub-slab suction is generally not as effective in reducing high radon levels as active sub-slab suction.
• Some houses have drain tiles or perforated pipe to direct water away from the foundation of the house. Suction on these tiles or pipes is often effective in reducing radon levels. One variation of sub-slab and drain tile suction is sump hole suction. Often, when a house with a basement has a sump pump to remove unwanted water, the sump can be capped so that it can continue to drain water and serve as the location for a radon suction pipe. Block wall suction can be used in basement houses with hollow block foundation walls. This method removes radon and depressurizes the block wall, similar to sub-slab suction. This method is often used in combination with sub-slab suction.

Crawlspace Houses:

• An effective method to reduce radon levels in crawlspace houses involves covering the earth floor with a high density plastic sheet. A vent pipe and fan are used to draw the radon from under the sheet and vent it to the outdoors. This form of soil suction is called sub-membrane suction, and when properly applied is the most effective way to reduce radon levels in crawlspace houses.
• Another less-favorable option is active crawlspace depressurization which involves drawing air directly from the crawlspace using a fan. This technique generally does not work as well as sub-membrane suction and requires special attention to combustion appliance back-drafting and sealing the crawlspace from other portions of the house.
• In some cases, radon levels can be lowered by ventilating the crawlspace passively (without the use of a fan). Crawlspace ventilation may lower indoor radon levels both by reducing the home’s suction on the soil and by diluting the radon beneath the house. Passive ventilation in a crawlspace is achieved by opening vents, or installing additional vents. In colder climates, for either passive or active crawlspace ventilation, water pipes, sewer lines and appliances in the crawlspace may need to be insulated against the cold. These ventilation options could result in increased energy costs due to loss of conditioned air from the house.

Other radon reduction techniques that can be used in any type of house include: sealing, house/room pressurization, heat recovery ventilation, and natural ventilation:

• Sealing cracks and other openings in the foundation is a basic part of most approaches to radon reduction. Sealing the cracks limits the flow of radon into your home thereby making other radon reduction techniques more effective and cost-effi cient. It also reduces the loss of conditioned air. The EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently. It is difficult to identify and permanently seal the places where radon is entering. Normal settling of your house opens new entry routes and reopens old ones.
• House/room pressurization uses a fan to blow air into the basement or living area from either upstairs or outdoors. It attempts to create enough pressure at the lowest level indoors (in a basement for example) to prevent radon from entering into the house. 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 be left closed, except for normal entry and exit. This approach generally results in more outdoor air being introduced into the home, which can cause moisture intrusion and energy penalties. Consequently, this technique should only be considered after the other, more common techniques have not sufficiently reduced radon.
• Heat Recovery Ventilator (HRV), also called an air-to-air heat exchanger, can be installed to increase ventilation which will help reduce the radon levels in your home. An HRV will increase ventilation by introducing outdoor air while using the heated or cooled air being exhausted to warm or cool the incoming air. HRVs can be designed to ventilate all or part of your home, although they are more effective in reducing radon levels when used to ventilate only the basement. If properly balanced and maintained, they ensure a constant degree of ventilation throughout the year. HRVs can also improve air quality in houses that have other indoor pollutants. There could be significant increases in the heating and cooling costs with an HRV, but not as great as ventilation without heat recovery.
• 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 outdoor air with the indoor air and can result in reduced radon levels. However, once windows, doors and vents are closed, radon concentrations often return to previous values within about 12 hours. Natural ventilation in any type of house should normally be regarded as only a temporary radon reduction approach because of the following disadvantages, loss of conditioned air and related discomfort, increased costs of heating or air conditioning and security concerns.Lowering high radon levels requires technical knowledge and special skills.  

Radon resistant techniques work. When installed properly and completely, these simple and inexpensive passive techniques can help to reduce radon levels. In addition, installing these when constructing a house makes it easier and less costly to activate the system to reduce levels further, if the passive techniques don’t reduced levels below 4 pCi/L. Radon-resistant techniques may also help to lower moisture levels and other soil gases.

Below are typical cost ranges provided by the EPA as of Dec. 2006. Many factors can affect this so only use them as a guideline, your actual costs may vary.  The fan electricity and house heating/cooling loss cost range is based on certain assumptions regarding climate, your house size, and the cost of electricity and fuel. Costs for cosmetic treatments to the house may increase the typical installation costs.

You should test your home again after it is fixed to be sure that radon levels have been reduced. Most soil suction radon reduction systems include a monitor that will indicate whether the system is operating properly. In addition, it’s a good idea to retest your home regularly or use an "Electronic Digital Detector" to be sure radon levels remain low.