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
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
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
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
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.
RADON RISK EVALUATION CHART
|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:
||About 35 people may die from radon
||Having 2,000 chest X rays/year
||About 17 people may die from radon
||Smoking 2 packs of cigarettes/day
||About 9 people may die from radon
||Smoking 1 pack of cigarettes/day
||About 5 people may die from radon
||Having 500 chest X rays/year
||About 2 people may die from radon
||Smoking half a pack of cigarettes/day
||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
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.
For more information, you may send us email
,or pick up the phone and give us a call.
We look forward to hearing from you.
2247 Springfiled Rd
Bloomington, IL, 61701
(309)275 3402 (Jerry)