Radon

This is an overview of the issue as prepared in 1995 and reviewed again in 1997. It is a constantly changing issue and if you discover high levels of radon in your home, you should consult a competent testing laboratory before deciding on the best action to take.

What Is It?

Radon is a radioactive decay by-product of uranium. If allowed to decay for an infinite length of time, thousands of years literally, uranium will simply turn into non-radioactive lead. During the course of its decay, it will give off radon gas. Radon gas is a colorless, odorless, tasteless gas. By itself, it is not a concern. However, the radioactive by-products of the radon gas are potentially hazardous. These are highly charged particles often referred to as radon daughters, radon progeny or alpha particles.

Where Does It Come From?

Radon gas enters our houses through two primary paths. The first is gases migrating out of the soil directly into the air within our homes. The second is through water that passes through potential radon sources such as granite.

Radon in air is of considerably more concern than radon in water. When we breathe air containing radon daughters, those highly charged particles can damage the lung tissue and, in sufficient concentration, could lead to lung cancer. Radon in water is typically not a problem with public water supplies. If you have a private well, it should be checked for radon.

We believe all houses should be tested for radon. The most vulnerable houses, however, are those with stone foundations, exposed rock ledge in the basement, dirt floors in the basement or crawl space, and those having block foundations. All these types of structures provide more opportunity for radon to get into the house.

What Level Is Hazardous?

The Environmental Protection Agency (EPA) has defined an "action level" for radon of 4.0 picoCuries per liter (pCi/L). No safe level has been determined. These levels are as stated in the EPA publication Citizens Guide to Radons 1.

Radon is measured in picoCuries per liter (pCi/L) which is best accepted simply as a measure of radioactivity. Currently, most estimates indicate that the average level of radon in all homes throughout the country is probably about 1.3 pCi/L. Similarly, the average level of radon outside our homes in the general atmosphere is probably about 0.4 pCi/L.

EPA Recommended Testing Steps
(from A Citizen's Guide to Radon)

Step 1: Take a short-term test. If your result is 4.0 pCi/L or higher, take a follow-up test (Step 2) to be sure.

Step 2: Follow up with either a long-term test or a second short-term test:

For a better understanding of your year-round average radon level, take a long-term test.

If you need results quickly, take a second short-term test.

The higher your initial short-term test result, the more certain you can be that you should take a short-term rather than a long-term follow-up test. If your first short-term test result is several times the action level - for example, about 10.0 pCi/L or higher, you should take a second short-term test immediately.

Step 3: · If you followed up with a long-term test, fix your home if your long-term test result is 4.0 pCi/L or more.

If you followed up with a second short-term test, the higher your short-term results, the more certain you can be that you should fix your home. Consider fixing your home if the average of your first and second test is 4.0 pCi/L or higher.

Interpretation Of Test Results

Some published information refers to PicoCurie-hours per week to interpret the significance of test results. This determination is based on radon level, and hours of exposure. This method of interpreting the results of radon tests is not endorsed by the EPA. EPA has not established any risk based action level since no level is determined to be a safe level. The formula used to determine PicoCurie-hours per week is based on an exposure associated with 4.0 pCi/L as though that were a safe level. No such determination has ever been made by the EPA. 4.0 pCi/L has been established as a level that most homes can achieve with appropriate mitigation. 4.0 pCi/L should not be considered an indication of what level is safe.

The only meaningful association with risk that EPA endorses is the published "Risk" table in the Citizens Guide to Radon1. A copy of the table is attached.

The American Association of Radon Scientists and Technologists (AARST) reinforced the fact that 4.0 pCi/L should not be considered a safe level or an acceptable exposure level. Further, they consider translating 4.0 pCi/L into PicoCurie-hours per week or evaluating an assumed exposure time as a cutoff point related to risk as an inappropriate and misleading risk evaluation method.

Test Location

Current EPA and State requirements are specific for a real estate transaction. Two test devices should be placed in the lowest livable area. The intent, as explained in the EPA publication Home Buyer's and Seller's Guide to Radon 2 is to provide an extra degree of assurance with regard to the accuracy of the test, realizing that only one brief opportunity to test may be the basis for a decision to buy a piece of real estate. The preference of the EPA continues to be a more extended test.

While an additional test device placed on an upper floor of a house will provide more information, it should not be done by compromising the basic testing protocol, i.e. two test devices in the lowest livable level, nor should it influence the interpretation of those results.

AARST specifically notes that the EPA standard should not be compromised by doing an additional test on an upper level. That additional test should be over and above the two test devices at the lowest livable level.

The EPA does suggest that the actual location of the radon test can be negotiable between the buyer and seller, subscribing to the guidelines offered in their publication, Home Buyer's and Seller's Guide To Radon 2 . In other words, it may be decided (by agreement between the buyer and seller) that a test be conducted on a level other than the currently lowest livable level.

What Test Procedures Are Available?

The most common test procedures currently are those using either an activated charcoal canister (in two sizes) or a sensitized film. The former is generally referred to as a charcoal test and the latter a track etching or alpha track test. Both are safe to handle.

The activated charcoal test provides a brief look at the level of radon in the home since it is taken typically during a 48 or 72 hour period. On the other hand, an alpha track test allows the sensitized film to remain in the home for a period of six months or more and provides more accurate data regarding the average level of radon in the house rather than a one-time sample.

No one sample should be relied on as conclusive evidence that action is necessary. This is especially important if a charcoal test is performed. It should be kept in mind that it is based on only a brief sampling in the house. Many studies that have been done indicate that radon levels in a house can vary significantly from day to day, hour to hour, and season to season. This is the primary reason why additional testing is suggested when radon levels above 4.0 pCi/L are encountered.

Test equipment to report immediate results from a "grab sample" is also available. This involves simply taking a sample of the air for a few minutes and producing an immediate indication of the amount of radon present. We consider these test procedures to be extremely unreliable due to the highly variable nature of radon presence. Longer tests are much more relevant.

Mechanical test equipment is also available that will monitor radon levels for an extended period of time and report on the level of radon hour by hour. If this device is used for an extended period of time (at least a week or more), it can produce some very useful information by indicating the peaks and valleys of radon presence as well as trends. This equipment is quite expensive and not typically in use for residential testing at this time.

Recent information has eroded our confidence in the two day tests. While these may be the only practical test available that can be conducted in the course of a routine real estate transaction, to base one's home purchase decision on these tests is, in our opinion, not recommended.

A more practical approach may be to purchase the home and then proceed with an extended period of testing after which improvements can be made, if necessary. Perhaps even an escrow account with the seller of the property could be established to correct the problem in the event that a six to twelve month study reveals that work is required.

What Is The Health Risk?

Unfortunately, many articles have appeared in newspapers and magazines that have taken a "the sky is falling" approach to the radon problem. We agree that it is a significant issue. We do not, however, agree that it is the basis for such headlines as "THREE OUT OF EVERY TEN HOMES WILL KILL YOU."

The following is the "Risk" table from the current EPA publication, Citizens Guide To Radon 1 . PLEASE NOTE THE REFERENCE "EXPOSED OVER A LIFETIME". THIS IS AN IMPORTANT PERSPECTIVE.
Most studies to date indicate that continued exposure to radon levels of approximately 10 pCi/L is roughly equivalent to the degree of risk of lung cancer resulting from smoking one pack of cigarettes a day.

It should be noted that those studies typically define continuous exposure as being 75% of your time for approximately 70 years. In other words, the effects of radon are cumulative. Virtually no hazard exists from brief exposures to even extremely high levels of radon.

Radon Risk If You Smoke

Radon Level
If 1,000 People who smoked were exposed to this level over a lifetime...
The risk of cancer from radon exposure compares to...
WHAT TO DO: Stop Smoking and ...

20 pCi/L
About 135 People could get lung cancer
< 100 times the risk of drowning
Fix your home

10 pCi/L
About 71 People could get lung cancer
< 100 times the risk of dying in a home fire
Fix your home

8 pCi/L
About 57 People could get lung cancer
(left blank by EPA)
Fix your home

4 pCi/L
About 29 People could get lung cancer
< 100 times the risk of dying in an airplane crash
Fix your home

2 pCi/L
About 15 People could get lung cancer
< 2 times the risk of dying in a car crash
Consider fixing between 2 and 4 pCi/L

1.3 pCi/L
About 9 People could get lung cancer
(Average indoor radon level)
Reducing radon levels below 2 pCi/L is difficult

0.4 pCi/L
About 3 People could get lung cancer
(Average indoor radon level)
Reducing radon levels below 2 pCi/L is difficult

---

Radon Level
If 1,000 People who never smoked were exposed to this level over a lifetime...
The risk of cancer from radon exposure compares to...
WHAT TO DO:

20 pCi/L
About 8 People could get lung cancer
< The risk of being killed in a violent crime
Fix your home

10 pCi/L
About 4 People could get lung cancer
(left blank by EPA)
Fix your home

8 pCi/L
About 3 People could get lung cancer
< 10 times the risk of dying in an airplane crash
Fix your home

4 pCi/L
About 29 People could get lung cancer
< The risk of drowning
Consider fixing between 2 and 4 pCi/L

2 pCi/L
About 1 People could get lung cancer
< The risk of dying in a home fire
Consider fixing between 2 and 4 pCi/L

1.3 pCi/L
< 1 person could get lung cancer
(Average indoor radon level)
Reducing radon levels below 2 pCi/L is difficult

0.4 pCi/L
< 1 person could get lung cancer
(Average indoor radon level)
Reducing radon levels below 2 pCi/L is difficult

NOTE: If you are a former smoker, your risk may be higher.

Most of the studies done to date have been based on high level exposures experienced by miners working in uranium mines. Only now are we beginning to do studies that would give us more accurate information regarding the risk in our homes.

How Is It Best Controlled?

Fortunately, even significant concentrations of radon in air are relatively easy to control. There are several excellent documents put out by the Environmental Protection Agency that discuss these methods in detail and if you wish to pursue this matter, you should obtain copies of them. They are generally available free of charge.

Briefly, the control methods suggested fall into two categories. First, in existing construction, consider the following:

Seal off the path through which radon is entering.

Provide positive ventilation into the basement of the house, using a heat exchanger or ventilation fan. Keep in mind that positive ventilation is important since an exhaust fan that creates negative air pressure in the house might actually encourage additional radon to enter.

Second, in new construction, consider the following:

If the building is yet to be built, ventilation systems can be installed under and around the foundation (sub-slab ventilation) to intercept the radon gas before it enters the structure at all.

If the structure is already built, the same procedures of sealing cracks or introducing a positive ventilation system are recommended.

Radon in water is handled differently. Currently, the so-called action level for radon in water varies considerably from state to state. Most seem to agree that 20,000 pCi/L in water is an appropriate action level. However, some states and even the Federal Government are considering much lower standards.

Radon in water can be controlled through filtration or aeration. Aeration seems to be emerging as the preferred procedure since it is a straightforward, dependable procedure that vents the radon directly to the outside.

What To Watch Out For?

There is an increasing number of radon mitigation specialists going into business throughout the United States. The work necessary to cure a radon problem is not complex, sophisticated or magical. Essentially, it involves a combination of sealing the radon out and/or providing ventilation to neutralize it. Spending large amounts of money with radon mitigation specialists is often unjustified. Careful study of the exact circumstances, using long term testing, is recommended before any action is taken.

Companies that provide both radon testing and radon mitigation should be avoided, if possible. Since the reliability of any testing is questionable, to rely on the same company to test and then recommend mitigation procedures leaves you, as a consumer and homeowner, very vulnerable. Testing should be done independently and evaluated objectively before deciding to proceed with any mitigation.

If you have reason to conduct several radon tests for the purpose of studying your home or building over a long period of time, we recommend that at least one test device be returned to the lab, unopened, for testing. The results should be zero. If they are not, the testing procedures used by the lab must be questioned. Obviously, this raises questions about the reliability of all of their testing.

Conclusion

Radon is a hazard in our environment. However, it has existed for thousands of years and we are only beginning to learn of its significance. We know that sufficient cumulative exposure can be hazardous in much the same way as is smoking. We also have determined that it is relatively easily controlled once the source and presence is identified.

Prudent, mature handling of the issue is, in our opinion, more important than panic.

For more information, contact your local Health Engineering Office or State Environmental Protection Agency (EPA) office.

1 A Citizen's Guide to Radon (Second Edition), United States Environmental Protection Agency, Air and Radiation (ANR-464), #402-K92-001, May 1992.

2 Home Buyer's and Seller's Guide to Radon, United States Environmental Protection Agency, #402-R-93-003.