A STORY ABOUT RADON
By Richard Acree
HABITEC Home and Building Inspections, LLC
The US Environmental Protection Agency (EPA) has designated January is the National Radon Action Month. This is a story about radon that everyone should read. First a brief review.
Radon is an odorless and invisible radioactive gas that is produced from the natural breakdown of the uranium found in most rocks and soils. As the breakdown occurs, radon emits atomic particles into the air we breathe.
Once inhaled, these particles can be deposited in our lungs. The energy associated with these particles can alter cell DNA, thus increasing the risk of lung cancer. In fact, the Surgeon General of the US has warned that radon is the second leading cause of lung cancer in the US. The National Academy of Science estimates that radon causes between 15,000 and 22,000 lung cancer deaths each year in the US. Any home can have radon. The only way to know if your house has a radon problem is to test (sample). For this reason, the EPA and Surgeon General recommend testing all homes for radon every two years! More on this later.
On average, 1 out of every 15 homes in the US is estimated to have an elevated radon level. The risk of radon exposure varies by location. The EPA has designated 3 zones of risk in the US, based on geological surveys. Zone 1 is a High Risk area, Zone 2 is a moderate risk area, and Zone 3 is a low risk. Most of the United States is in either Zone 1 or Zone 2. A map depicting the zones is available at http://www.epa.gov/radon/zonemap.html.
Radon is normally measured in pico curies per liter (pCi/L). The EPA guidance says that if a home radon measurement is equal to or higher than 4 pCi/L, the home should be mitigated. In other words "fixed". The EPA goes on to say that even if your home were to test below 4.0 pico curies (below the action level) there is NO absolutely safe level of radon.
Now back to the story. I am a home owner in Brentwood, TN and I am also the President and a Home Inspector at HABITEC Home and Building Inspections, LLC. In the fall of 2005, I tested my own house for radon. The test was set up in my finished basement. The results came back as 2.7 pCi/L, below the EPA action level. Although this initial measurement was below the action level of 4.0 pCi/L, I purchased and installed a continuous radon monitor as part of my personal radon monitoring program. For the next 6 months my radon level remained at an average of 2.7 pCi/L. Then, in the spring of 2006, my radon level started to climb. Over a period of two months it reached a level of 10.7 pCi/L, almost four times what it was just six months prior and well above the EPA action level!
Now it is widely known among radon measurement technicians that radon levels can be affected by such things as weather and ventilation. In this case there had been some rain but it was not out of the ordinary. Also, the HVAC system was operating about as it was when the fall test was run. So what could have caused this event? An investigation would ensue; however, the radon level was high and had to be corrected regardless.
A radon mitigation company was contracted and an active radon mitigation system installed. A subsequent radon measurement was taken and the radon level now indicated below 2.0 pCi/L. Whew! Problem solved. But what could have caused the radon to take off like that?
Further evaluation may have solved the puzzle. Apparently, there is growing evidence that blasting associated with construction can have an effect on radon measurements. When we think about it, if construction is underway nearby and blasting is part of the process, there has been ample evidence that the blasting can rattle nearby homes and buildings. Sometimes this blasting may even cause structural damage including cracks in concrete and bricks. It is also known that radon can enter a home through cracks in the foundation. It follows then that if a foundation develops a crack from whatever source, the potential for radon to enter the home goes up.
Another possibility is the effect of blasting on the rocks and soil below or abeam a foundation. If concrete can crack because of blasting, it is possible that limestone or other more fragile rock could also crack. Compacted soil may also loosen. If either of these conditions occur, it may be possible for radon to be more easily emitted by the subterranean conditions near the structure.
Although it is virtually impossible to connect the dots directly between the blasting and the elevated radon level, it is certainly a possibility. So the moral of the story is if you have heard blasting near your home, it might be a good idea to have your home tested for radon. Besides, earlier it was pointed out that the EPA recommends testing every 2 years anyway.
Reference the 2 year rule offered by the EPA. HABITEC suggests that home owners in Zones 1 or 2 with a full basement or a home built over slab-on-grade should have there homes checked every year. We say this because we live in a Zone 1 area and because of the difference between the ventilation associated with basements or slabs and crawl spaces. We say this also because of the story we are telling in this article. Better safe than sorry.
HABITEC Home and Building Inspections, LLC, provides building inspections for residential and commercial buildings. Additionally, we offer environmental services to evaluate a structure for radon, mold and water quality. Please visit our website at http://www.habitecinspections.com/. Richard Acree is certified by the National Environmental Health Association as a Residential Radon Measurement Provider.