Some environmental safety officials have criticized the Environmental Protection Agency, which conducted the studies, for being unduly alarmist. Richard Guimond, 40, director of the EPA's Office of Radiation Programs, strongly disagrees, calling radon "an extremely serious problem." Guimond spoke with correspondent Margie Bonnett Sellinger about radon testing and remedies.
How many homes in the U.S. are threatened by elevated radon levels?
About 10 percent of the houses in this country may have a radon problem. That means there are probably 8 million homes that should have their radon levels reduced.
How does radon get into a home?
Uranium breaks down to form radon, which then moves through the soil and escapes into the atmosphere. That's not much of a problem until you put a house over the escaping gas and trap it. Holes in the basement floor, drains or sumps offer perfect entry points.
How does radon harm humans?
Radon attaches itself to dust, which is then inhaled and deposited in the upper regions of the lungs. The decaying materials give off alpha particles, which are strong forms of radiation. That radiation can cause cancer.
How many cases of lung cancer can be attributed to radon?
We believe that it's causing as many as 20,000 deaths from lung cancer in the U.S. each year. Currently there are about 140,000 lung cancer deaths annually, and estimates are that about 85 percent are related to cigarette smoking.
And the rest can be blamed on radon?
A substantial portion. There is, of course, an overlap. If you are exposed to both radon and smoking, it's much, much worse than if you're exposed to just one or the other. Of the estimated 20,000 radon-related fatalities, probably 75 to 85 percent are due to radon and smoking combined.
How was radon linked to lung cancer?
There are studies of miners throughout the world going back several decades. We've learned that these miners are five to 10 times more likely to get lung cancer than the rest of us.
When was the radon threat discovered in houses?
In 1984 a nuclear plant worker named Stanley Watras tripped radiation detectors at a plant near Reading, Pa. The plant was not operating, and since Watras tripped the detectors when entering, it was clear that he hadn't been exposed at work. Plant officials then took some measurements at Watras' home and found radiation levels that were more than 200,000 times above the level permissible for people living next to nuclear power plants. They found similar levels in many houses in Pennsylvania and New Jersey situated over a geological formation called the Reading Prong.
How was it determined that radon was not just a local problem?
In the belief that the situation at the Reading Prong was not unique, the EPA began survey programs. The first was completed a year ago in 10 states. An additional seven states were studied this year. The states were selected largely at their request, and each survey covered about 11,000 homes.
What did you find?
Elevated levels of radon were present in every state we tested. The readings in Alabama showed that just 6 percent of the houses were above four picocuries of radon per liter of air. [A picocurie is a trillionth of a curie, a standard measure of radiation.] In North Dakota and the Reading Prong area of Pennsylvania, almost 64 percent of the houses exceeded four picocuries. Most states were in the 20 to 40 percent range.
What is the significance of the four picocuries level?
We call four picocuries our "action level," the level at which something should probably be done to remove radon from a house. Four picocuries per liter carries a risk that is the equivalent of smoking about half a pack of cigarettes a day. If you are exposed to that much radon over your lifetime, you have perhaps a 1-in-100 chance of getting lung cancer. If it's 20 picocuries per liter, then it's about a 1-in-10 chance of getting lung cancer, almost like smoking two packs a day.
How do you test for radon in a house?
Take a detector containing activated charcoal and leave it in a room. It will absorb whatever radon is in there. After two to seven days, tape the detector up and mail it to a laboratory, which puts it on a special radiation monitor to get a measurement. We recommend doing these screenings in the winter—when your house is tightly closed—in the lowest level of the house. There is also something called an alpha track detector that is used for longer measurements. This is left in place for two months to a year.
Which one should a homeowner use?
You can begin with either, but the charcoal detector is quicker. The cost of either test runs from $10 to $30. If the results exceed four picocuries, then we recommend follow-up measurements with either alpha tracks or charcoal detectors placed throughout the house at different times of year.
How quickly must you take action?
If the measurement is above 200 picocuries per liter, you should act as soon as possible. Between 20 and 200, you should get the radon level reduced within a few months. Between four and 20, we recommend that you do it within a year or so. Under four, you can make your own decision.
How do you fix a radon-threatened home?
Close and seal the openings to the ground—major cracks in the foundation, openings to crawl spaces, sumps—with polyurethane caulking or other appropriate materials. Radon seepage that is only moderately elevated may be substantially reduced this way. For houses with very high radon levels, the most successful method is called sub-slab ventilation. Essentially, this involves installing a pipe in the gravel under the house and running the pipe to the roof where a fan sucks out the contaminated air.
Is this expensive?
No. A pretty good do-it-yourselfer can probably do it for $200-$300 without help. If you get someone to do it for you, the cost typically will run between $800 and $1,500.
Is there a danger of fraud in the radon testing and remedial business?
Yes. In order to protect the consumer, the EPA has made a list of radon-testing companies that pass our requirements. This list is made available to all state health and environmental agencies. We are planning a similar proficiency program for companies doing repair work. Currently, about a dozen states have 800 numbers to call for information.
If my neighbor has no radon problem, am I safe too?
Unfortunately, you have no way of looking at a house or the ground it sits on and knowing whether the house will be safe from radon. The people next door to Stan Watras didn't have much of a radon problem. You can have a geological fracture that runs under your house but not the one next door.
Would you recommend testing as part of any house sale?
I wouldn't buy a house not tested for radon.
Why is it so hard to get the public to take the radon risk seriously?
You can't smell it, you can't taste it, you don't know it's there. I've often said that if I could make radon smell like dirty socks, then I could get people to take it seriously. But the perception of a home, sweet home is that it is safe. In fact, your home could give you the highest radiation exposure you'll ever get in your life.
It is a colorless, odorless, radioactive gas that has been around as long as the planet Earth. Yet, until four years ago, few would have thought that radon, which occurs naturally from the breakdown of uranium in the earth's crust, posed much of a threat to humans—except for miners deep underground. Then a potentially lethal accumulation of radon was discovered in a Pennsylvania home, and soon there were indications that the problem was widespread. After conducting two surveys during the past two years in 17 states, the federal government two weeks ago issued a sweeping advisory urging that every dwelling in the U.S.—detached and row houses and apartment buildings through the second floor—be tested for radon.