Radon that enters your home eventually decays into radon decay elements. It is these decay products that are of concern to us. While radon is a gas, these radioactive elements are solid particles that become suspended in air. As we inhale these extremely small particles, they attach themselves to our lung tissue. Because these particles have very short half lives, our lungs do not have the time to exhale them out before they break down. It is the break down of these particles that releases alpha, beta, and gamma radiation directly into our sensitive lung tissue. Most hazardous of these is alpha radiation. It can kill a lung tissue cell, and/or cause a mutation in the cell’s DNA causing that cell to develop into a cancerous cell. This leads to an increased risk of developing lung cancer over prolonged exposure.
Pressurization uses a fan to blow air into the basement or living area from either upstairs or outdoors. The goal here is to create enough pressure (positive pressure) at the lowest level indoors, such as in a basement, to prevent radon from entering the house. The effectiveness of this technique can be limited by house construction and climate. 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. Blowing air out of the basement to reduce radon levels, although seemingly a good idea, might actually increase the flow of radon into your home. As you blow air out, a vacuum effect is created (negative pressure) which will cause greater influx of radon into your basement from the surrounding soil.
Another form of ventilation is natural ventilation, which is achieved simply by opening doors and windows at the lower levels of your home. Natural ventilation mixes outdoor air with the radon contaminated indoor air, thus reducing overall radon levels.
There are some obvious drawbacks to both of the above techniques. Once you close your windows and doors, or turn off your fan that blows air into your basement, radon concentrations most often return to previous values within about 12 hours. Furthermore, as a result of more outdoor air being introduced into the home, you might see moisture intrusions, loss of conditioned air, and energy penalties, particularly during the winter months.
Consequently, both of these techniques are regarded as only temporary approaches to radon reduction and should only be considered after the other, more-common techniques (such as sub-floor mitigation) have not sufficiently reduced radon levels.
Another form of mechanical ventilation can be accomplished by installing a heat recovery ventilator (HRV), sometimes referred to as air-to-air heat exchanger. HRVs ventilate by introducing outdoor air while using the heated or cooled air being exhausted to warm or cool the incoming air. The advantage of an HRV system over other ventilation techniques is that besides supplying balanced ventilation, a HRV will reduce the energy penalty associated with providing more ventilation to a home. As an added benefit, an HRV can improve air quality in houses that have other indoor pollutants.
Sealing the cracks in the foundation and other openings, such as drainage and sump pump sinks, is a basic part of most approaches to radon reduction. This technique reduces the flow of radon into your home thereby making other radon reduction techniques more effective and cost-efficient, and also reduces the loss of conditioned air. This technique, however, has its limitations. It is difficult to identify and permanently seal all the places where radon can enter, and if you have a finished basement, this is almost impossible without extensive and possibly expensive work. Furthermore, even if you were able to do so in an unfinished basement, normal settling of your house will eventually open new entry routes and reopen old ones.
You can try a special floor drain adapter for your drainage holes in your basement. I myself have purchased couple of these Dranjer D-R2 floor drains. They allow for water to flow down the drain but prevent any gas/air from coming up through it into the living space. According to the website I purchased these from it does the following: “Dranjer seals permit unrestricted flow of water into floor drains or sump pits while sealing out the entry of mold spores, insects and radon gas from the sub-slabe floor area.” To be completely honest, I am not sure these worked very well, as my radon detector did not register any significant changes.
As a side note: 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