Radon​—A Danger in Your Home?

AN ENGINEER who worked at the Limerick nuclear power plant in the eastern United States found that even without entering the plant power area, he set off the alarm that monitored radiation. When it became evident that he was not picking up radiation within the nuclear plant, his house was tested, and it was found to be the source of the contamination.

A 68-year-old missionary recovering from double-bypass heart surgery had difficulty overcoming anemia even though he was receiving medication to build up his blood. One of the questions the doctor asked was: “Have you ever been exposed to radiation?”

“Yes,” he answered. “In my early 20’s, I worked for two years as a technician in a plant where I was exposed to radon.”

“That may be your problem,” the doctor concluded.

Both the engineer at the nuclear power plant and the man who suffered from anemia had been exposed to an invisible danger, radon.

‘Radon. What is that? And could it be a danger in my home?’ you may ask.

What Is It?

Radon, an odorless, colorless gas, is one of six chemical elements that are known as noble, or inert, gases. Radon, however, differs from the other five noble gases in that it is radioactive. It is a product of the decay of the radioactive element radium.

Radioactive elements emit certain rays, or particles, and in the process of decay, these elements change into other substances. Thus, the radioactive metal uranium eventually becomes radium. When an atom of the metal radium emits radiation, it changes into an atom of radon. Radon, in turn, decays into radioactive products that are known as its daughters.

The rate at which a radioactive substance decays is called its half-life. The half-life of radon is a little less than four days, which means that in about four days, half of the original radon will have decayed into other substances. On the other hand, the half-life of radium is 1,660 years and that of uranium is 4,500,000,000 years! Thus, in its natural state, uranium is more abundant than radium because uranium has a much longer half-life.

Source of the Problem

In any uranium ore, there will always be a certain amount of radium, as well as small quantities of radon. This radioactive gas, which can find its way into one’s home, is the source of the problem.

The quantity of uranium found in the rocks and soil will vary greatly from place to place. This means that in certain areas a significant amount of radon may seep slowly from the soil. If the radon escapes into the open air, it will soon disappear. But if the gas happens to be under a house, it may be trapped there and gradually seep into the basement of the house through cracks in the floor or walls or through sumps and drainage pipes.

Radon is also found in underground water, so it can find its way into homes through the water system as well. The risk is not so much from drinking the water as from inhaling the gas that is released from the water as one washes, showers, or cooks.

The experience of the Limerick nuclear-plant engineer mentioned in the introduction illustrates the potential danger. The foundation of his house was discovered to have been poured over an outcropping of uranium-bearing rock. The radioactivity in the living room measured 3,200 picocuries, whereas the EPA (Environmental Protection Agency) recommends that measures be taken to reduce radon levels in homes that measure above 4 picocuries per liter of air.a

According to one estimate, the family received the same amount of radiation in the year that they lived in the house as they would have received from 260,000 chest X rays! Thus, their chances of developing lung cancer were greatly increased. The family wisely moved out until the situation was corrected. “I don’t smoke and I never touched alcohol when I was pregnant,” the wife lamented. “But then I bring my babies to live in a radioactive cloud.”

High levels of radiation have also been found in places in Denmark, France, Germany, Greece, Italy, the Netherlands, Sweden, and the United Kingdom. Many uranium miners exposed to radon have died from lung cancer. In fact, a writer for The New York Times claims: “No one questions [radon’s] ability to cause lung cancer, a disease that used to kill half of uranium miners, who inhaled large amounts of radon breakdown products every workday.”

How Great the Danger?

Since radon that is breathed into the lungs is largely exhaled before it decays, it itself does not pose a significant problem to health. However, the “daughters”​—the radioactive products into which radon decays—​can be dangerous. These products are chemically active and adhere to tiny dust particles that may stay in the lungs. Thus, lung tissue can be affected by the radiation. As Dr. Anthony Nero, Jr., senior scientist in the Lawrence Berkeley Laboratory of the University of California, explains: “Because they [the radioactive products into which radon decays] have short half-lives, once collected in the lung, it is highly probable that they will decay [there].”

The danger from exposure to radon in homes has been investigated only in recent years, and no one really knows what is a safe level of exposure. Earlier this year the EPA reduced its estimate of the danger. “We previously estimated up to 21,000 cancer deaths per year due to radon and that figure is now perhaps 16,000,” says Dr. Richard J. Guimond, an EPA official. Nevertheless, he claims: “Radon is still one of the larger health risks people face.” Yet, no one can point with certainty to any cancer cases due to radon exposure in the home.

Some, in fact, believe that the concern over radon is greatly exaggerated. William Mills, a former head of the EPA, says that the number of cancer deaths attributed to radon is inflated because many of these deaths should be blamed on smoking. “My view,” he says, “is that the real risk from radon is between zero and some number near zero.” Of a similar opinion is Roger Eaton, head of a radon group within the Canadian government’s department of health and welfare. “Our experience,” he says, “is that lung cancer is a rare disease when there’s no smoking involved.”

Smoking evidently significantly increases the danger of radon to those exposed to it. Science magazine says that exposure to radon multiplies the risk of lung cancer in smokers by at least ten times. It is not known why radon affects smokers more than nonsmokers, but some experts feel that smoke-damaged lungs may tend to trap radioactive products of radon decay.

Some areas are known hot spots for radon. In Clinton, New Jersey, in the United States, it was found that all homes tested in one community had high levels of radon radiation. Five homes had so much that it was estimated that living in them all their lives would give the occupants the same risk of lung cancer as would smoking 20 packs of cigarettes a day!

Dr. Nero explains: “Many people in these areas are living in homes with radon levels above 20 picocuries, levels greater than the occupational limit for miners.” Nero estimates: “There are about 100,000 such households, and these people really do need help.”

The EPA has warned that eight million American homes have radon levels that probably exceed the federal guideline of four picocuries per liter of air. Yet, some experts believe the EPA estimate of homes at risk is exaggerated. They also question the degree of danger that low levels of radon represent. Dr. Bernard L. Cohen, professor of physics and radiation health at the University of Pittsburgh, said: “My interpretation of the data is that low-level exposure is essentially harmless; there is no effect at very low levels, as are found in most homes.”

What About Your Home?

The danger that radon poses to you depends largely upon the concentration of uranium in the soil where you live. Another important factor is the type of soil beneath your home; more permeable soils permit the entry of greater amounts of radon even if the radium content of the soil is low.

Yet another risk factor is the way that your home is built. For example, many modern homes have been built to be virtually airtight in order to conserve energy. Thus, radon that seeps into them cannot readily escape. As an EPA official explained: “The more you try to button up a house, the higher the pollutant levels become.” Thus, drafty older houses are probably safer from the potential danger of radon.

A known hot spot for uranium in the United States is an area stretching from eastern Pennsylvania across northern New Jersey and into New York. Another is the Red River valley area between Minnesota and North Dakota. If you live in such a known hot spot, having the air inside your home tested to determine its level of radon may be wise.

However, regardless of the location of your home, the test results are unpredictable. One house in Pennsylvania had a radon level of 2,694 picocuries, but the one next door had a reading of only 3.6! Then again, high indoor radon levels can turn up in areas not known to be uranium hot spots. Because of such unpredictability, an EPA director says: “All we’re asking people to do is spend $10 to $20 to find out if they have a problem.”

If you decide to have your home tested, there are different ways to do it. You may want to obtain information from local agencies on environmental control. “The guideline is for the average exposure in the rooms where you live,” Dr. Nero notes. “But most of the EPA’s screening,” he says, “is done with detectors placed in basements.” He also emphasizes: “Monitoring should last for months, and ideally for a year.”

It would be wise to exercise care in selecting a firm for testing, since some are more reputable than others. Radon detectors can also be purchased. But reports indicate wide variation in accuracy from model to model.

If after testing you find that your home has a high level of radiation, the problem can be handled. Perhaps sealing cracks in the basement walls and floor and using fans to improve the ventilation will be sufficient. In Clinton, New Jersey, the community mentioned earlier where all the homes had high levels of radiation, the first ten homes worked on had their levels reduced to safe limits within six months. The job of correcting the problem rarely costs more than $1,500​—and generally much less.

In very unusual situations, such as that of the nuclear-plant engineer, extensive work may be necessary. The concrete basement floor and much of the earth below had to be removed. The house foundations were covered with a special plastic radon barrier, and all cracks in the concrete were filled with silicone. Finally, a special ventilation system was installed. The effort to reduce the radon to a safe level proved successful, though at an expense of $32,600.

Happily, evidence seems to indicate that the radon threat in homes is not as extensive as had been feared. But if you are in doubt about your home, you may want to have it tested for your own peace of mind.

[Footnotes]

[Pictures on page 13]

How radon may enter a home

Fumes from well water

Cracks in floors and walls

Loose drainage pipes

Granite

Well water

Cracks in floor

Porous blocks