Ticking Time Bomb

Radon a killer PDF Print E-mail
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Earthquakes and volcanic eruptions demand our attention, but not all subterranean killers announce themselves so boisterously. One in particular is both sinister and stealthy, creeping into millions of homes across the United States every day and night, killing thousands of people each year. 

Radon is the country's No. 2 cause of lung cancer, behind only cigarette smoke, and has a yearly U.S. death toll of about 21,000 people. It's a naturally occurring, radioactive gas that's colorless, odorless, tasteless and chemically inert, so it can easily go unnoticed in someone's house for years. The EPA estimates that about one in 15 American homes has elevated radon levels. 

 

How radon gets inside

Nearly all soils contain low levels of decaying uranium, which emits radon gas, although certain regions have more than others.  It's normally harmless — groundwater absorbs some of the radon, and the rest floats to the surface and radiates softly into the air. The problems arise when ascending radon hits the underside of a building. If it finds any openings (see the graphic above for examples), it seeps through to the inside — because air pressure is lower indoors than in the surrounding soil, the building acts like a vacuum, sucking the radon in.

That's especially dangerous in enclosed areas like basements and cellars, where trapped radon can build up to high densities. On the flip side, though, radon usually isn't a danger above the second or third floor of a building. Even if it can't squeeze through the floors and walls, radon can still sneak in with the water.

Wells or public water supplies that use groundwater are especially at risk, since groundwater absorbs radon from soil and rocks, but surface-water supplies may also be contaminated. Radon in water poses a mild risk for stomach cancer when ingested, but the main threat is still inhaling it, which can happen after it's released from the water in the shower or at the sink.    

Granite countertops caused a stir recently when studies pointed out that granite can emit small amounts of radon. The EPA acknowledges this, but says radon from granite countertops is so miniscule that, in most cases, it's not dangerous. The majority of indoor radon gas still comes from soil, but the EPA recommends testing your home for radon regardless of its source.  

Areas with large deposits of uranium, as well as granite, shale and phosphate, are likely to have higher levels of radon wafting up from the soil. The long-term use of phosphate fertilizers on cropland may also increase soils' uranium content, and therefore the risk of radon exposure. Still, the determining factor on whether airborne radon gets inside is ultimately a building's foundation. A house in Pennsylvania in 1984 that had the outrageously high radon level of 2,700 pCi/L was 100 feet away from another house, on the same soil and geologic formation, whose radon levels were normal. Well-built houses can be radon-free even in high-risk areas, and vice versa. That's why the EPA warns against relying on the map above to decide whether to worry about radon exposure. The only way to know for sure is to test your home.

 

How to test for radon

The easiest starting point is a do-it-yourself radon test kit, which you can find online, at a hardware store or other retail outlet. If you're buying or selling a home, however, you may want to hire a qualified radon tester to come by your house. Check with your state radon office for a list of qualified testers, or try one of the two national, privately run radon-testing programs. But the cheapest way is usually to just do it yourself. There are two kinds of home radon tests: short-term and long-term. 

short-term test remains in your home for two to 90 days, depending on the type, and is the fastest way to find out if you have a radon problem. But because radon levels often vary from day to day and season to season, short-term tests aren't always reliable. 

Long-term tests, such as "alpha track" or "electret" detectors, stay in place for more than 90 days, and generally give readings that more accurately represent your home's year-round average. If your short-term test reveals a radon level of 4 pCi/L or more, the EPA recommends doing either a short-term or long-term follow-up. 

The average indoor radon level is about 1.3 pCi/L, and outdoors it's normally about 0.4 pCi/L. Congress' long-term goal of reducing indoor radon throughout the United States to outdoor levels still isn't practical in many cases, but most homes now can be at least brought down to about 2 pCi/L. Still, no radon is safe to breathe, and the EPA points out that any reduction in radon exposure reduces the risk of lung cancer. How to handle a radon problem 

The EPA has compiled a comprehensive handbook for ridding your home of radon, the Consumer's Guide to Radon Reduction, which lists a variety of methods, depending on a house's foundation type. Some radon-reduction techniques simply remove radon that's already entered, while others prevent it from entering in the first place; the EPA recommends the latter

 
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