Radon exposure is second only to smoking as a cause of lung cancer. What level of radon in the home and long you can safely be exposed to it are the subject of much debate, although the U.S. Environmental Protection Agency has established an annual average of 4 picocuries per liter of air (pCi/L) as the level that indicates you should reduce radon levels in your home. To put this in perspective, the average home is estimated to have levels about 1.3 pCi/L.
There is no way to know for sure how much radon there is in your home without testing; the good news is that radon testing is easy to do and inexpensive.
Two types of testing are done; short term and long term testing. Kits for both kinds can be purchased at hardware stores for between $20 and $40. You could also hire a professional service to perform testing as an alternative. Local government organizations conduct promotions from time to time offering free testing or rebates on test kits, so check around.
It is recommended that you start with a short term test, which will take around 1 week for sampling and a couple of weeks for the analysis. Should the short term test results show radon at levels higher than 2 pCi/L but less than 10 pCi/L, you should conduct a long term test. The long term testing lasts up to one year. The idea is that short term results can vary from season to season and even day to day, so they are less accurate.
On the other hand, if the short test resulted in a reading of 10 pCi/L or higher, then do another short term test and take an average of the two results. This will give a slightly more accurate indication and let you take appropriate action in a timely manner.
Some sort of radon mitigation should be done within the next few months in this case. If the levels in your home test as over 200 pCi/L, then mitigation should be done within weeks, and you should consider relocating temporarily until it has been done.
Testing levels of radon in water is simple, it is just of matter of collecting a water sample and sending it to a qualified laboratory for analysis. Radon in water is only a problem if your home uses water from an underground source, such as a well or underground springs. Other water sources such as the rivers, lakes and reservoirs that supply most municipal water systems have exposure to open air and thus dissipate any absorbed radon.
Radon Testing Kits
Testing kits typically use some form of passive method. There are a few different types, but the most common uses a charcoal monitor. These have a small canister containing activated carbon which absorbs radon. The canisters are placed in different locations and left there, for a couple of days to a week, depending on the manufacturers instructions. After that, the canister is mailed off to a laboratory for analysis and results will be mailed back to you, usually within a week.
It is important to follow the test instructions provided by the kit manufacturer. The lowest lived-in level of the house should be tested, as well as the basement if it is frequently used. Windows and doors to the tested area should be kept closed for a minimum of twelve hours prior to starting the test. In order to rule out water-borne radon as a potential reason for high test results, any appliances or plumbing fixtures using well water should be shut off for twelve hours prior to and during the test.
Individual radon monitors need to be located at least a few feet from each other. They should be at least eight inches below a ceiling and twenty inches above a floor. Placement in kitchens and bathrooms should not be done, unless you are testing separately for radon in the water supply, since humidity and temperature levels in these areas are higher and will skew readings.
Another type of radon testing device that is more suitable for long term testing is the digital type. These are more expensive and use electronic monitoring to display results on an LCD screen or stored in memory. As you will probably only want to purchase one, placement of this type of monitor is critical.
Radon Testing Services
If you are unable to perform testing yourself, professional testing is available. It is also useful in buying or selling a house, where only results from tests done by qualified professionals are accepted. Qualified professional testing companies can be found in the yellow pages of your telephone book, or by contacting your municipal radon office.
Find out what tests and services the company will perform and compare with other companies, as you would when hiring any other professional contractor. Some companies have specialized testing equipment, while others only do passive testing with the same kits you can do yourself. The newer devices are able to immediately take readings of radon levels as well as locate the spots where radon is entering the home.