Are you concerned about radon?
Some government agencies and health-interest groups think you should be.
The U.S. Environmental Protection Agency identifies radon as the "No. 1 environmental pollutant" and says it is second only to smoking as the cause of lung cancer. The American Lung Association says radon is responsible for "thousands" of the 140,000 lung cancer deaths each year.
What is it, exactly? Radon is a colorless, odorless, radioactive gas that comes from the natural breakdown of uranium in the soil. Radon occurs in nearly every part of the country; some areas have higher levels than others. Radon hot spots occur in Colorado, Florida and in a broad band of the eastern seaboard from Pennsylvania to Connecticut. In Maryland, the highest average levels are in Carroll County; the lowest are in Worcester and Wicomico.
Radon gets into houses from below, through cracks, gaps, mortar joints, exposed soil (in crawl spaces, for instance, or around a sump pump), in spaces around loose-fitting pipes, drains or French drains in the basement floor, through the open tops of concrete blocks, and with water from an underground source. If it reaches concentrations above 4 pico-Curies per liter (a measure of radiation), according to EPA, it's a hazard and you should take steps to reduce it.
While no one disputes the fact that high concentrations of radon increase the risk of lung cancer, there is some evidence that the radon "scare" of six years ago was short-lived.
For one thing, there is controversy over the actual number of lung cancer deaths attributable to radon. Some critics contend that areas of the country with high levels of radon are the same places where lung cancer deaths are low. EPA has revised downward its "estimated" number of radon-induced lung cancer deaths per year, from 20,000 a few years ago to the current 13,000. Legislation to establish a national policy to deal with radon has languished. At least one company that leaped into the radon-test-kit business a few years ago has filed for bankruptcy.
So what's a homeowner to do?
Play it safe. Radon-testing kits are widely available, they're simple to use and they're not expensive. And if a test reveals a radon problem, the remedies are not difficult and may not be expensive.
There are two types of radon-detecting tests: Charcoal detectors, $10-$25 each, which are set out for a week or so then sent off to a lab for analysis; and alpha-track devices, just slightly more expensive, which are more accurate but take a minimum of four weeks before analysis.
Start with the simplest first. Place charcoal canisters in the basement and first floor. According to the EPA, levels about 200 pico-Curies per liter mean a serious problem that needs immediate action. A level between 20 pCi/l and 200 pCi/l is above average and action should be taken to mitigate it, while doing a follow-up test of no more than three months. A level between 4 pCi/l and 20 pCi/l means follow-up measures are advisable and detectors should be exposed for a full year, or four one-week periods during each season. Relatively low concentration levels, below 4 pCi/l, are about average and generally do not require follow-up action.
Never act on the basis of your neighbor's reading; you must test your own house. Radon levels can vary hugely from house to house depending on what's underneath.Loose soil will allow more radon to seep through, clay will allow less.
If the test shows a slightly elevated level of radon, you may be able to reduce it to acceptably safe levels simply by ventilation -- leaving basement windows open. If you live in a climate where that's not practical, implement the simpler steps first and test again.
Start by sealing basement cracks.
*Seal floor cracks with grout (in traveled areas) or rubberized caulk (where it won't be kicked up).
*Paint porous walls with a commercial sealer.
*Seal cracks in walls with mortar or caulk.
*Seal gaps around pipes with caulk (for a small hole) or mortar and caulk (for a larger hole).
*Seal joints between walls and floors with caulk. If you have French drains around the perimeter walls, seal them with concrete and caulk. (If you have a water problem, you'll have to solve it externally.)
*Seal the top row of exposed cinder block with mortar.
*Cover exposed dirt with concrete. If you have a sump-pump well, cap it.
*Remove and seal floor drains.
L *Seal off crawl spaces from the basement and ventilate them.
Then test again.
If the simpler methods haven't worked, you may need a more radical -- and somewhat more expensive -- solution. Try to find a contractor with experience in radon mitigation. Prices may vary considerably, so competitive bids are a good idea. You may be able to get a list of contractors in your area from the local department of the environment.
More serious mitigation methods are: