I can not lie. I copied the entire content from a continuing education program I was taking the other day. I know what radon is, however, this excerpt seems to do a better job at explaining than I ever can.
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Radon gas decays, giving off radioactive particles. Radon gas enters buildings through cracks in basement floors and walls, openings around pipes and electrical services into the basement, water supplies, and basement floor drains. Radon exists in patches or streaks like veins of gold; your house may be fine, but the one next door could be contaminated.Radon became a national health concern in the U.S. in the mid-1980s. The U.S. Environmental Protection Agency (EPA) and the National Cancer Institute estimate that between 15,000 and 22,000 deaths occur annually in the U.S. as a result of lung cancer caused by radon gas exposure. As with cigarette smoking, the harmful effects occur over time, and vary directly with the level of exposure. Exposure occurs primarily in the victim’s home.
The EPA and the U.S. Surgeon General recommend radon testing for every homeowner.
Here are various ways to test for radon gas. Some hardware stores carry home testing kits. After testing is complete, the kits are sent to the manufacturer for analysis. Many professional property inspection companies offer radon testing as well. Because radon is everywhere in the soil in trace amounts, testing will reveal minute quantities of radon gas in virtually every building. It only becomes a health issue when levels become elevated.
If testing reveals a problem, it can usually be cured without too much difficulty. Solutions include sealing cracks and openings, improving basement or crawlspace ventilation, or pressurizing the basement to reduce gas infiltration from the ground.
Mechanical radon mitigation methods
(Source: “The Consumer’s Guide to Radon Reduction” by EPA)
Covering exposed earth in basement reduces ingress of radon, as does sealing cracks and openings in ground level walls and floors.
Drain-tiles can be placed surrounding the foundation and vented away from the house (the drain-tile suction method). This method is designed to pull radon from the soil surrounding the house and vent it away from the house.
Sub-slab suction is more difficult to accomplish, as it involves placing pipes under the house (laterally through side walls or by drilling holes in the concrete slab). A fan is used to vent these pipes away from the house.
Concrete block walls can be vented by sucking air from the hollow spaces in the wall and venting it away from the house to prevent radon from re-entering.
Lastly, there are methods for decreasing negative pressures within the house by bringing air into the house in proportion to losses from chimneys, dryers, etc., or by positive pressure including basement pressurization by blowing air from upper floors into the sealed basement.
Combustion gases and fan-suction mitigation systems
Radon mitigation fans draw not just soil gas from the ground but also indoor air from the house through cracks and pores in concrete. This may cause combustion spillage from the furnace, water heater, or fireplace in modern, tight houses.
Houses are already depressurized due to combustion appliances, exhaust fans like in the bathroom and kitchen (may exhaust 750 cfm), clothes dryers, range hoods, natural “stack effect,” etc. The radon mitigation fan flow of say 100 cfm is comparable to a clothes dryer. In a leaky house, this may reduce air pressure by only 1 Pa but in a tight house, it may produce depressurization of 5–10 Pa which will reverse chimney flows. If the house is already depressurized at say 4 Pa, adding the radon mitigation system may take it over the limit of 5 Pa.
Building codes believe that each appliance should provide its own make-up air. And they rely on passive openings but dependent on wind direction, they may actually draw more air from the house. Spillage resistant appliances (e.g. direct vent gas appliances) are a much more reliable solution. Installing a CO alarm is a good idea.
The RadonSeal mitigation method
Unlike paints or surface sealers, RadonSeal concrete sealer penetrates deep inside concrete (up to 4″), chemically reacts with lime, and permanently seals the capillaries in concrete. RadonSeal must be applied to all concrete in contact with the ground, be it a basement or a foundation slab.
RadonSeal just seals the concrete. Afterwards, all cracks or openings have to be sealed and caulked just like with any other radon mitigation method. By using RadonSeal, most homeowners reduce radon to the 1 – 2 pCi/L range. The theoretical bottom limit is the natural level of radon in the ambient air, which averages 0.45 pCi/L in the U.S. but exceeds 1 pCi/L in some areas.
The plagiarism ends here…
Bottomline is that although radon is not a common occurrence in Westchester, it should be part of a normal home inspection. The day you don’t test for it is the day you’ll need it. You should perform a radon test prior to signing a purchase contract so you can make sure the seller will address the issue if one exist. The seller can refuse to remediate the problem, but you can also refuse to purchase the home. You may face a stubborn seller (never happens), but ultimately they’ll be living with the problem if you chose not buy the home, so it’s in their best interest to deal with the problem there and then.
