Frequently Asked Questions About Radon

1. What is radon?
Radon is a radioactive gas that comes from the decay of radium in the soil. Radium is a decay product of uranium. Radon is a colorless, odorless, invisible gas that occurs naturally. Chronic exposure to elevated radon levels has been linked to an increased incidence of lung cancer in humans.

2. Are radon levels something I really need to be concerned with?
Yes. For most people, radon is their largest source of exposure to nuclear radiation. The US Environmental Protection Agency (EPA) has identified radon as the second leading cause of lung cancer in the United States. Many homes, particularly homes in the upper midwest, contain radon concentrations that are high enough to give their occupants lifetime exposures of the same size as those received by underground miners who showed the increased risk of lung cancer mortality. see FAQ 19.

3. What is it about radon that makes it harmful?
When radon and its decay products are inhaled into your lungs they emit alpha particles. These alpha particles can strike the sensitive lining of the bronchi. When this happens, the cells in your lungs are damaged, subsequently increasing your risk to radon-related cancer. Most of the alpha particle radiation comes from radon decay products. However, since it is easier to measure radon rather than its decay products, people usually characterize the exposure by the amount of radon in their living spaces.

4. What elements of the environment contain radon?
Radon is constantly being generated by the radium in rocks, soil, water and materials derived from rocks and soils. Radium is present at about 0.5 to 5 parts per million (PPM) in common rocks and soils. The radon generated in rocks or water usually stays trapped in that material unless the rocks are highly fractured or the water is mixed with the air. Radon generated in soil has about a 40% chance of escaping into the soil gas.

5. How does radon move around?
Radon can move by diffusion in response to a concentration difference or by advection in response to a pressure difference. Radon leaves the ground generally by diffusion. Radon travels into houses generally by a combination of diffusion and advection. In most soils radon doesn't travel more than a few feet before decaying.

6. What is the most accurate way to measure radon levels?
Continuous electronic radon monitors generally produce the most accurate radon measurements. However, they are expensive and can be difficult to operate. Year-long measurements by alpha-track (ATD) detectors in your living spaces provide adequate measurements for decision-making. In most homes, radon varies dramatically from day-to-day, week-to-week, season-to-season, and to a lesser extent year-to-year. This means that if you want to assess your long-term exposure to radon, you need to measure over a period of a year or more. In addition, in my opinion, you only need to know your average radon exposure to an accuracy of about 25% in order to make a decision about what steps you might take to reduce your radon exposure. ATDs can readily supply that information at a reasonable cost.

7. Is it a good idea to do both short and long-term tests?
Possibly. If you have reason to suspect that you might have extremely high radon or if you just can't wait a year for the results, then take a short-term test and start a long-term test alongside. A year-long test in a living space where you spend a lot of time would be the most efficient and effective way for the first assessment of the radon hazard in your home.

8. What does pCi/L mean?
Picocuries per liter (pCi/L) is a unit for measuring radioactive concentrations. The curie (Ci) unit is the activity of 1 gram of pure radium 226. Pico is a scientific notation term which means 1×10¯¹². Another unit commonly used for radioactive concentrations is the SI unit Becquerels per meter cubed (Bq/m³). A Becquerel is one radioactive disintegration per second.

9. Are radon levels affected by the ventilation in my house?
Yes. Sometimes radon concentrations can be reduced to acceptable levels by increased ventilation. Most of the time, other methods are needed to reduce radon levels (mitigate) to acceptable levels (see FAQ 12 and 13).

10. What levels of radon are safe?
Unknown. Studies of the effects of radon in homes have produced mixed results. Some studies indicate a positive association, others don't. These are very difficult studies to do well because smoking-related lung cancer is such a large component of the total lung cancer rate and because it is very difficult to reconstruct the lifetime dose from radon decay products for any individual. It is virtually impossible to avoid exposure to radon concentrations below 1 pCi/L because outdoor air is generally contains radon concentrations from 0.1 to 1 pCi/L.

11. What levels of radon are acceptable?
You must provide the answer to this question based on the following data and your personal risk tolerance. If you lead a normal life, live in spaces that average 4 pCi/L of radon, and if you are: (a) a never smoker, (b) an ex-smoker (c) a smoker, then your lifetime risk of getting lung cancer that is related to your radon exposure is about (a) 1 chance in 250; (b) 1 chance in 100; (c) 3 chances in 100. For comparison, substances in the food chain are regulated at levels that produce much lower risks. Usually food or drink is labelled contaminated if they produce a 1 in 100,000 lifetime chance of producing cancer. Most scientists believe that above about 10 pCi/L the risk associated with radon would increase in direct proportion with the radon concentration. Below this value, many believe that the risk decreases in direct proportion but that there could be a safe threshold value. We don't know for sure what that value is or whether it exists.

12. Can anything be done to reduce the hazard associated with radon?
Yes, definitely. Often the solution is simple and inexpensive. However, the best solution depends on the size and nature of the radon risk. For example, suppose you find that your basement bedroom has high radon. A possible simple solution might be to avoid spending long stretches of time in that room by moving your bedroom to a lower radon room upstairs, if that option exists. Other situations may require other mitigation solutions. The "standard" active mitigation system, that usually involves soil depressurization, costs about $500 to $2000 installed.

13. Who can mitigate my radon problem?
You probably can if you're handy. In many areas, contractors (called mitigators) are available too. The EPA and your state health department can provide you with additional information, including instruction manuals and names of RCP-listed mitigators. Whoever does the work, be sure to make periodic long-term measurements to insure that the system continues to reduce your radon to acceptable levels.

14. Does the age of my house affect the radon level?
Possibly. Some houses show an increase of radon with age, other houses show a decrease and still others show no change with age. Unfortunately, we haven't found any single factor like the age of the house, energy efficiency, or basement structure that can accurately predict the radon level in any house. You really have to measure the radon in your house to know for sure.

15. Why are radon levels in my home "high" while those in my neighbor's home are "low?"
Many things influence the amount of radon in a home. The variation in radon levels from home-to-home comes from the variation in the factors that control radon entry and retention. There are so many factors like the structure of the soil, the way the house is connected to the ground, the way the house is heated and cooled, that it is extremely difficult to predict accurately the radon in neighboring homes. We've found that, in ILLINOIS neighborhoods, most of the homes are within a factor of 2 of the neighborhood average. So, for example, if three of your neighbors made measurements and they averaged 20 pCi/L, your home is likely to have radon between 10 and 40 pCi/L. It is very likely to exceed the EPA's 4 pCi/L action level.

16. Are there areas where radon is likely to be high?
Yes. We've found that the average radon can vary dramatically from town to town.

17. Is high indoor radon unique to ILLINOIS?
No. The average US home contains about 1.3 pCi/L while the average ILLINOIS home has more than 3 pCi/L.

18. Are there any other health effects with radon?
Not that we know for sure. No other cancers or diseases have yet been positively associated with radon exposure. However, radon is absorbed into the body and can irradiate tissues other than the lung.

19. Is radon-related lung cancer fatal?
Most often, yes. Lung cancer is a disease that has a very poor survival rate. Prevention is the most effective defense. Don't smoke and don't breathe elevated concentrations of radon.

pCi/L picocuries per litre	WL working level	If a community of 100 people was exposed to this level:	This risk of dying from lung cancer compares to:
100	0.5	About 35 people may die from radon	Having 2,000 chest X rays/year
40	0.2	About 17 people may die from radon	Smoking 2 packs of cigarettes/day
20	0.1	About 9 people may die from radon	Smoking 1 pack of cigarettes/day
10	0.05	About 5 people may die from radon	Having 500 chest X rays/year
4	0.02	About 2 people may die from radon	Smoking half a pack of cigarettes/day
2	0.01	About 1 person may die from radon	Having 100 chest X rays/year

Is Radon A New Problem?

Underground miners have been dying of radon-induced lung cancer for centuries, though radon and lung cancer weren't clearly linked until the 1950s and 1960s.

A curious incident in 1984 grabbed the attention of the scientific community and eventually led to the realization that naturally occurring radon could be a significant health threat inside residential dwellings. In December of that year, an employee of the nuclear power plant in Limerick, Pennsylvania, set off a radiation detector upon entering his work facility. The man's home was subsequently monitored for radiation and found to contain a shockingly elevated level of radon. At 2,700 pCi/l the worker's house contained more than 13 times the level of naturally occurring radon ever expected to be found inside a private residence. The man was actually contaminated with radiation from the radon inside his own home.

Widespread radon testing conducted after this incident revealed that residential radon was a problem national in scope. In September 1988, the Surgeon General recommended that all homes, except residences above the second floor in multi-level buildings, conduct radon screening tests.

How Does Radon Enter A Home?

Radon can seep into a home through dirt floors, cracks and pores in concrete walls and floors, hollow-block walls, joints, drains pipes, and sump pumps. Building supplies made from materials containing uranium are rarely a significant source of residential radon.

20. Dora Babb is an EPA RMP/RCP listed individual and meets EPA requirements of the US EPA Radon Proficiency Program and is listed with the Illinois Department of Nuclear Safety.