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\3Intelligent Layman's Guide to Radon\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \[\1p. \@\,
\=
\+
\^\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \"The Intelligent Layman's Guide to Radon\ \ \ \ \ \ \ \ \ \ \ \ \ \ \^\,
\+
\,
\+
\^\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \4Abstract\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \^\,
\+
\,
\+
\1Radon is a radioactive gas ("noble" gas) produced by \ the \ radioactive 
\+
decay of naturally occurring uranium traces in the soil. \  Because \ it 
\+
is chemically inert it is odorless and tasteless. Since uranium \ is \ a 
\+
common element, radon is everywhere in our environment.  \,
\+
\,
\+
Recently environmentalists have begun to worry that because of the way 
\+
houses are constructed, radon can concentrate in cellars and basements 
\+
to a level many times that found outdoors. This is more-or-less \ inde-\A
\+
pendent of whether the house is of modern "air-tight" or older "leaky" 
\+
construction.\,
\+
\,
\+
The household accumulation of radon gas can lead to elevated \ exposure 
\+
to nuclear radiation, compared with living in \ a \ tree, \ for \ example. 
\+
This talk aims to discuss how concerned you should be about this.\,
\+
\,
\+
\,
\+
 A. What is radiation?\,
\+
\,
\+
\ \ \ \ Radiation is a generic term that \ describes \ particles \ travelling 
\+
\ \ \ \ from one point in space to another. All such particles carry ener-\A
\+
\ \ \ \ gy that they can transmit to any matter they collide with. We \ are 
\+
\ \ \ \ interested in the effects of various types of radiation on \ living 
\+
\ \ \ \ creatures, especially ourselves.\,
\+
\,
\+
\ \ \ \ Sometimes the particles making up radiation collide with the \ mat-\A
\+
\ \ \ \ ter of a living organism. Then, depending on how much energy \ they 
\+
\ \ \ \ transmit, they can interfere with the functioning of \ living \ tis-\A
\+
\ \ \ \ sue. The processes of life are carried on by \ chemical \ reactions, 
\+
\ \ \ \ in which complex molecules are \ produced, \ taken \ apart \ or \ rear-\A
\+
\ \ \ \ ranged.  The precise order of these reactions is \ very \ important, 
\+
\ \ \ \ so if they get disrupted the living cell could die \ or \ be \ trans-\A
\+
\ \ \ \ formed in some way. One type of transformation that does not \ kill 
\+
\ \ \ \ the cell occurs when it becomes cancerous. \,
\+
\,
\+
\ \ \ \ If an injured cell dies outright there is no problem \6-= \ \1our \ body 
\+
\ \ \ \ replaces it. This happens all the time in our bodies. \ Of \ course, 
\+
\ \ \ \ if too many cells die before they can be \ replaced, \ then \ \!we \ \1get 
\+
\ \ \ \ sick or die. However, a cell that is transformed to a cancer \ cell 
\+
\ \ \ \ is dangerous.  If our defense mechanisms do not detect and kill it 
\+
\ \ \ \ right away, it can reproduce and form a potentially lethal tumor. \,
\+
\,
\+
\ \ \ \ I will now classify various familiar types of radiation \ according 
\+
\ \ \ \ to their effects on human beings. The more energy the particles of 
\+
\ \ \ \ radiation transmit to our living cells, the more effect \ they \ can 
\+
\ \ \ \ have. We classify them according to increasing energy per particle 
\+
\ \ \ \ because this is the same as listing them according \ to \ increasing 
\+
\ \ \ \ danger.\,
\+
\,
\+
\,
\+
    1. Kinds of radiation, classified by \ increasing \ energy/particle. \,
\+

\+
\ \ \ \ \ \ \ "Penetrating" means radiation like x-rays that pass through our 
\+
\ \ \ \ \ \ \ skin, "non-penetrating" radiation is stopped at our skin.\,
\+
\,
\+
       a) Electromagnetic spectrum:\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \ Non-penetrating and not biologically active:\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \[radio\ \ \ \ \ \ \ \ \ \ \ \ \ \[TV, radar, microwave ovens\,
\+
\ \ \ \ \ \ \ \ \ \ infrared  \ \ \ \ \ \ \ \ \[Heat lamps, radiant heaters, wood stoves\,
\+
\ \ \ \ \ \ \ \ \ \ visible light  \ \ \ \[Sun, artificial lights\,
\+
\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \ Non-penetrating, but biologically active:\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \ ultraviolet\ \ \ \ \ \ \ \[UV tanning lights, Sun\,
\+
\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \ Penetrating (depth depends on energy), biologically active:\,
\+
\,
\+                                                                \0)
\ \ \ \ \ \ \ \ \ \ \1x-rays\ \ \ \ \ \ \ \ \ \ \ \ \[x-ray machines (doctors, dentists)\,
\+                                                                \0} \1same
\ \ \ \ \ \ \ \ \ \ \7g\1-rays\ \ \ \ \ \ \ \ \ \ \ \ \[radioactive decays, cosmic rays\,
\+
\,
\+                                                                \00
\,
\+
       \1b) Alpha particles:\ \ \[Penetrating, very bio-active.\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \[Nuclei of helium atoms. Produced in \ radioactive \ decays \ of 
\+
\ \ \ \ \ \ \ \ \ \ heavy elements, they have enough energy to disrupt \ about \ 5 
\+
\ \ \ \ \ \ \ \ \ \ million molecules. \,
\+

\+
\,
\+
\,
\+
       c) Beta rays:\ \ \ \ \ \ \ \ \[Short-range, bioactive.\,
\+
\ \ \ \ \ \ \ \ \ \[Electrons emitted in radioactive decays. Can \ disrupt \ about 
\+
\ \ \ \ \ \ \ \ \ \ 1 million molecules.\,
\+
\,
\+
       d) Cosmic rays:\ \ \ \ \ \ \[Extremely penetrating, bio-active.\,
\+
\ \ \ \ \ \ \ \ \ \[Extremely energetic hydrogen nuclei from outer \ space. \ Part 
\+
\ \ \ \ \ \ \ \ \ \ of the background radioactivity that we experience \ all \ the 
\+
\ \ \ \ \ \ \ \ \ \ time. There is no way to shield agains them. \,
\+
\,
\+
\,
\+
    2. How can radiation harm you?\,
\+
\,
\+
       a) Microwave ovens emit radio waves at \ wavelengths \ especially 
\+
\ \ \ \ \ \ \ \ \ \ absorbed by water molecules.  That \ is, \ the \ molecules \ act 
\+
\ \ \ \ \ \ \ \ \ \ like little radio receivers \ "tuned" \ to \ these \ "stations".  
\+
\ \ \ \ \ \ \ \ \ \ They absorb energy from the powerful radio beam and heat up. 
\+
\ \ \ \ \ \ \ \ \ \ Thus a leaky microwave oven can give you ordinary burns from 
\+
\ \ \ \ \ \ \ \ \ \ too much heat \6-= \1the same effect is used in surgical RF cur-\A
\+
\ \ \ \ \ \ \ \ \ \ ettes. \,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \ A microwave signal leaking out of a defective oven, or \ from 
\+
\ \ \ \ \ \ \ \ \ \ standing too close to a radar transmitter can interfere with 
\+
\ \ \ \ \ \ \ \ \ \ the delicate electronics of a pacemaker and injure \ a \ heart 
\+
\ \ \ \ \ \ \ \ \ \ patient. But microwaves will \!not \1give you \ cancer \ or \ cause 
\+
\ \ \ \ \ \ \ \ \ \ genetic mutations.\,
\+
\,
\+
       b) UV lamp or too much \ sun: \ "burns" \ to \ skin \ from \ chemical 
\+
\ \ \ \ \ \ \ \ \ \ damage. Possible skin \ cancer \ from \ long-term \ exposure \ in 
\+
\ \ \ \ \ \ \ \ \ \ people with low pigmentation. No genetic \ mutations \ because 
\+
\ \ \ \ \ \ \ \ \ \ it doesn't penetrate past skin.\,
\+
\,
\+
       c) Ionizing radiation from radioactive decays or \ cosmic \ rays: 
\+
\ \ \ \ \ \ \ \ \ \ energetic \7a\1, \7b \1or \7g \1rays pass through matter and knock elec-\A
\+
\ \ \ \ \ \ \ \ \ \ trons loose from atoms, causing unusual chemical \ reactions. 
\+
\ \ \ \ \ \ \ \ \ \ Damage to \ tissues, \ esp. \ chromosomes. \ When \ we \ speak \ of 
\+
\ \ \ \ \ \ \ \ \ \ hazardous radiation we usually mean this \ kind \ of \ ionizing 
\+
\ \ \ \ \ \ \ \ \ \ radiation, not radio waves, heat lamps or UV rays.\,
\+
\,
\+

\+
    3. Measures of nuclear radiation dosage.\,
\+
\,
\+
\ \ \ \ \ \ \ The amount of damage done by ionizing radiation \ is \ determined 
\+
\ \ \ \ \ \ \ by how much energy it deposits per kilogram of \ living \ tissue, 
\+
\ \ \ \ \ \ \ because that tells us approximately how many chemical reactions 
\+
\ \ \ \ \ \ \ it can cause (of which some small fraction will be dangerous to 
\+
\ \ \ \ \ \ \ the living cell). \,
\+
\,
\+
\ \ \ \ \ \ \ We measure dosage in \4Rad\1's.  This is equivalent in \ most \ cases 
\+
\ \ \ \ \ \ \ to the more common unit, the \4REM \1(\4R\1adiation \4E\1quivalent \4M\1ammal): 
\+
\ \ \ \ \ \ \ a measure of energy delivered \ per \ kilogram \ of \ tissue. \ Most 
\+
\ \ \ \ \ \ \ doses, say \ from \ natural \ backgound \ radioactivity, \ are \ much 
\+
\ \ \ \ \ \ \ smaller  than 1 \4REM\1, so we measure for convenience in 1/1000 of 
\+
\ \ \ \ \ \ \ a \4REM\1, or milli\4REM\1. For those who have \ to \ know \ the \ details, 
\+
\+                      \2-5
\ \ \ \ \ \ \ \11\6t\1milli\4REM\6t\1=\6t\110\ \  J/Kg. \,
\+
\,
\+
\ \ \ \ \ \ \ For comparison, a whole-body radiation dose that kills \ 50% \ of 
\+
\ \ \ \ \ \ \ those exposed from acute radiation sickness is about \ 400 \ \4REM\1, 
\+
\ \ \ \ \ \ \ or about 200-300 Joules of energy. A 0.22 caliber bullet deliv-\A
\+
\ \ \ \ \ \ \ ers about 135 J, and also kills about 50% of those hit in vital 
\+
\ \ \ \ \ \ \ areas of the body.\,
\+
\,
\+
\ \ \ \ \ \ \ However, we will be talking about very \ small \ radiation \ doses 
\+
\ \ \ \ \ \ \ that do not cause any detectable effects on the human body.\,
\+
\,
\+
\,
\+
 B. What is radon?\,
\+
\,
\+
\ \ \ \ Radon is a chemically unreactive gas ("noble" gas) produced by the 
\+
\ \ \ \ radioactive decay of naturally occurring \ uranium \ traces \ in \ the 
\+
\ \ \ \ soil.  Because it is chemically inert it is \ odorless \ and \ taste-\A
\+
\ \ \ \ less. Since uranium is a common element, radon \ is \ everywhere \ in 
\+
\ \ \ \ our environment.  Since it is a gas, it is inhaled with the air we 
\+
\ \ \ \ breathe. While it is inside our lungs, any radon atoms that under-\A
\+
\ \ \ \ go radioactive decay expose lung tissue to ionizing radiation that 
\+
\ \ \ \ can lead to lung cancer.  Later in the talk I will try to estimate 
\+
\ \ \ \ the hazard from this exposure so you will know how much to worry. \,
\+
    \,
\+                                  \2238
\ \ \ \ \11. Radioactive decay chain of \ \ \ U, the uranium in the soil:\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \[R.B. Leighton, \3Principles of \ Modern \ Physics \ \1(McGraw-Hill, 
\+
\ \ \ \ \ \ \ \ \ \ 1959) Fig. 15.3.\,
\+
\,
\+                   \2222      206
\ \ \ \ \ \ \ \ \ \ \1Decay of \ \ \ Rn to \ \ \ Pb releases about 17 MeV of energy \ \3via 
\+
\ \ \ \ \ \ \ \ \ \ \1the chain of shorter-lived decay products.  \,
\+
\,
\+
    2. Other naturally-occurring radioactivity\,
\+
\,
\+
\,
\+
 C. How is the effect of ionizing radiation on human beings determined?\,
\+
\,
\+
\ \ \ \ At very low doses, ionizing radiation produces \!no \1effect on \ human 
\+
\ \ \ \ beings or other living organisms detectible with present \ biomedi-\A
\+
\ \ \ \ cal technology.  Everything we can say about \ low-level \ radiation 
\+
\ \ \ \ is based on \!extrapolation \1downward from \ known \ effects \ of \ large 
\+
\ \ \ \ doses.  To help you understand what "small" and "large" mean, \ the 
\+
\ \ \ \ average background radiation dose (from the environment being nat-\A
\+
\ \ \ \ urally radioactive) is about 170 m\4REM\1/year to each person \ in \ the 
\+
\ \ \ \ United States.  On the other hand, \,
\+
\,
\+
    1. High-level dosage (\9>\6t\110 \4REM\6t\1=\6t\110,000 m\4REM\1)\,
\+
\,
\+
       a) Data from Hiroshima & Nagasaki survivors\,
\+
\ \ \ \ \ \ \ \ \ \ 23,979 survivors who got \9>\6t\1130\6t\4REM\,
\+
       \1b) Data from nuclear reactor accidents and fallout victims\,
\+
       c) Data from x-ray and radiation therapy\,
\+
\,
\+
    2. Low-level dosage\,
\+
       a) Data from Uranium miners\,
\+
\ \ \ \ \ \ \ \ \ \ 4,146 miners who got 468 \4REM \1over about 20 years \ of \ expos-\A
\+
\ \ \ \ \ \ \ \ \ \ ure; the excess of 119 lung cancer deaths \ translates \ to \ a 
\+                           \2-7
\ \ \ \ \ \ \ \ \ \ \1probability of 10\ \ /m\4REM\1, in agreement with other \ estimates 
\+
\ \ \ \ \ \ \ \ \ \ of cancer induction based on the linear hypothesis.\,
\+
\,
\+
       b) Uranium miners & smoking\,
\+
\ \ \ \ \ \ \ \ \ \ Most of the miners were heavy smokers. There is a known syn-\A
\+
\ \ \ \ \ \ \ \ \ \ ergy between radon exposure and \ smoking \ that \ greatly \ in-\A
\+
\ \ \ \ \ \ \ \ \ \ creases the chance of lung cancer for a \ smoker \ exposed \ to 
\+
\ \ \ \ \ \ \ \ \ \ radon, over that of an ordinary smoker. \  For \ a \ non-smoker 
\+
\ \ \ \ \ \ \ \ \ \ there is actually no known effect of low-level radon \ expos-\A
\+
\ \ \ \ \ \ \ \ \ \ ure. To be conservative, we usually assume the worst.\,
\+
\,
\+
       c) Experiments on lab animals and tissue cultures\,
\+
\ \ \ \ \ \ \ \ \ \ All such experiments consistent with a "threshold" effect.\,
\+
\,
\+
       d) Natural background doses\,
\+
          1) Variations with locale: 100-300 mR/yr is typical range in 
\+
\ \ \ \ \ \ \ \ \ \ \ \ \ US. \,
\+
\,
\+
          2) Correlation with health effects: essentially \ nonexistent 
\+
\ \ \ \ \ \ \ \ \ \ \ \ \ or anti-correlated! Colorado has \ higher \ background \ and 
\+
\ \ \ \ \ \ \ \ \ \ \ \ \ \!lower \1cancer rates than \ Louisiana, \ \3e.g. \  \1Radiation \ is 
\+
\ \ \ \ \ \ \ \ \ \ \ \ \ good for you!\,
\+
\,
\+
    3. Repair mechanisms and "dosage threshold".\,
\+
\,
\+
\ \ \ \ \ \ \ Since we are exposed to background radiation all the time, \ and 
\+
\ \ \ \ \ \ \ since there is little cancer observed from it, or harmful muta-\A
\+
\ \ \ \ \ \ \ tions, biologists infer that various \ repair \ and \ "correction" 
\+
\ \ \ \ \ \ \ mechanisms exist. This means that the result of \ low-level \ ex-\A
\+
\ \ \ \ \ \ \ posure will be \!less \1than predicted \ by \ extrapolating \ linearly 
\+
\ \ \ \ \ \ \ downward from the high-dose results. This is \!confirmed \1by \ epi-\A
\+
\ \ \ \ \ \ \ demiological studies and by lab-animal/tissue culture studies.\,
\+
\,\/
\+
    4. How does this translate \ to \ chances \ of \ getting \ cancer \ from 
\+
\ \ \ \ \ \ \ radon?\,
\+
\,
\+                    \2-12         10
\ \ \ \ \ \ \ \ \ \ \11 pC is 10\ \ \ \6t\9*\6t\13.7\9*\110\ \ /sec\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \ Lung \ capacity \ is \ \6t\9~\6t\12\6t\1Liters, \ and \ assume \ the \ dose \ is 
\+
\+                          \22
\ \ \ \ \ \ \ \ \ \ \1delivered to 4\7p\1R\ t where R\6t\9~\6t\110\6t\1cm, t\6t\9~\6t\10.025\6t\1cm \ of \ tissue, 
\+
\ \ \ \ \ \ \ \ \ \ \6t\9~\6t\10.031\6t\1Kg. The EPA standard is 4\6t\1pCi/L.\,
\+
\,
\+
\ \ \ \ \ \ \ \ \ \ This gives an estimated dose of\,
\+
\,
\+                \27                                -2
\ \ \ \ \ \ \ \ \ \ \13.2\9*\110\ \6t\1sec/yr\6t\9*\6t\12\6t\1L\6t\9*\6t\14\6t\1pCi/L\6t\9*\6t\13.7\9*\110\ \ /sec/pC\6t\9*\6t\117\6t\1MeV\,
\+
\+                   \2-13                  -5
\ \ \ \ \ \ \ \ \ \ \6t\9*\6t\11.6\9*\110\ \ \ \6t\1J/MeV/0.031\6t\1Kg/10\ \ \6t\9~\6t\190\6t\1m\4REM\1/yr\,
\+
\,
\+                                                               \2-7
\ \ \ \ \ \ \ \ \ \ \1The chance of getting cancer from 1 mR \ is \ \9<\6t\11.25\9*\110\ \  \ ac-\A
\+
\ \ \ \ \ \ \ \ \ \ cording to the linear hypothesis. Thus 90 m\4REM\1/yr translates 
\+
\ \ \ \ \ \ \ \ \ \ to\,
\+
\,
\+                         \26               -7
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \[\1250\9*\110\ \6t\9*\6t\190\6t\9*\6t\11.25\9*\110\ \ \6t\9~\6t\13000 cancers/yr\,
\+
\,
\+
\ \ \ \ \ \ \ The EPA estimate 5,000-20,000 \ cancers/year \ with \ an \ expected 
\+
\ \ \ \ \ \ \ number around 13,000 \6-= \1and you can see this is very \ uncertain 
\+
\ \ \ \ \ \ \ \6-= \1is based on the known synergistic effect of smoking and \ ra-\A
\+
\ \ \ \ \ \ \ don exposure (from the uranium miners studies).  That \ is, \ the 
\+
\ \ \ \ \ \ \ 30-40% of smokers in the population gets most of the lung \ can-\A
\+
\ \ \ \ \ \ \ cer.  Keep in mind that there are about 105,000 deaths/yr \ from 
\+
\ \ \ \ \ \ \ lung cancer, so most are not from radon exposure.\,
\+
       \,
\+
\,
\+
 D. How does radon compare with other hazards?\,
\+
\,
\+
\ \ \ \ One m\4REM \1of radiation corresponds to a reduction of life expectan-\A
\+
\ \ \ \ cy of 1.2 minutes. This is equivalent to crossing a city street \ 3 
\+
\ \ \ \ times or driving 3 miles, or taking 3 puffs of a cigarrette.\,
\+
\,
\+
    1. Eating one banana \,
\+
\ \ \ \ \ \ \ \ \ \[25\6t\1mR/body\6t\9*\6t\10.37\6t\1gm-K/banana\6t\1/150\6t\1gm-K/body\6t\1=\6t\10.06\6t\1m\4REM\,
\+
\ \ \ \ \ \ \ \ \ \[\7D\1L\6t\9~\6t\1-4\6t\1sec from radiation, \6t\9~\6t\1-5\6t\1min from calories\,
\+
\,
\+
    2. Smoking 1 cigarette \,
\+
\ \ \ \ \ \ \ \ \ \[\7D\1L\6t\9~\6t\1-10\6t\1min\,
\+
\,
\+
    3. Medical x-ray\,
\+
\ \ \ \ \ \ \ \ \ \[\6t\9~\6t\1200\6t\1mR \8+\96 \7D\1L\6t\9~\6t\1-4\6t\1hrs\,
\+
\,
\+
    4. Dental or chest x-ray\,
\+
\ \ \ \ \ \ \ \ \ \[\6t\9~\6t\110\6t\1mR \8+\96 \7D\1L\6t\9~\6t\1-12\6t\1min\,
\+
\,
\+
    5. Chemical carcinogens\,
\+
\ \ \ \ \ \ \ \ \ \[Most cancer due to them or \ other \ biological \ source, \ only 
\+
\ \ \ \ \ \ \ \ \ \ about 1 in 200 cancers due to radiation of any kind.\,
\+
\,
\+
    6. Remaining unmarried or living in city:\ \[\7D\1L\6t\9~\6t\1-5\6t\1yrs.\,
\+
\,\/
\+
 E. How does radon get in your house?\,
\+
\,
\+
\ \ \ \ Most houses exhaust inside air to the outside.  For \ example, \ oil 
\+
\ \ \ \ or gas heating systems, fireplaces, \3etc. \1burn inside air, and out-\A
\+
\ \ \ \ side air comes in through various cracks and leaks.  Some of \ this 
\+
\ \ \ \ outside air comes from the \ soil \ under \ the \ house, \ or \ diffuses 
\+
\ \ \ \ through brick and cement in the structure. The air in these mater-\A
\+
\ \ \ \ ials is much richer in radon than outside air \ generally \ (because 
\+
\ \ \ \ they are slightly radioactive), and radon \ is \ heavier \ than \ air. 
\+
\ \ \ \ Hence the air in the house can become somewhat enriched \ in \ radon 
\+
\ \ \ \ compared with the air outside.\,
\+
\,
\+
\ \ \ \ A second source of radon is well water, since \ it \ originates \ far 
\+
\ \ \ \ underground and has radon dissolved in it.\,
\+
\,
\+
    Sealing against drafts, \3etc. \1has little effect on how \ much \ radon 
\+
\ \ \ \ is found in the air in one's home.\,
\+
\,
\+
\,
\+
 F. How do you get rid of radon, assuming you want to? \,
\+
\,
\+
\ \ \ \ Several methods of treatment are available, \ differing \ widely \ in 
\+
\ \ \ \ price.  Which is appropriate depends on how \ bad \ the \ problem \ is 
\+
\ \ \ \ (see \6S\1G below).  If the radon \ level \ is \ high, \ you \ need \ expert 
\+
\ \ \ \ advice. \,
\+
\,
\+
    1. Ventilate basement. Any kind of ventilation will do, \ but \ will 
\+
\ \ \ \ \ \ \ lose heat in winter. Heat-conserving \ forced-draft \ ventilators 
\+
\ \ \ \ \ \ \ are commercially available that are \ relatively \ cheap \ to \ run 
\+
\ \ \ \ \ \ \ (\6t\9~\6t\1$50/yr) and not too expensive to buy and install (\9~\6t\1$200).\,
\+
\,
\+
    2. Aerate well water.  This gets rid of dissolved radon \ which \ is 
\+
\ \ \ \ \ \ \ flushed to outside air.\,
\+
\,
\+
    3. Negative pressure \ treatment \ under \ foundation: \ an \ air \ pump 
\+
\ \ \ \ \ \ \ reduces the pressure under your slab below that in \ the \ house, 
\+
\ \ \ \ \ \ \ so air now flows from your house out through the slab, \ instead 
\+
\ \ \ \ \ \ \ of \3vice versa\1. Costs \6t\9~\6t\1$500-$1,000.\,
\+
\,
\+
    4. Seal cracks in foundation to prevent air from soil getting \ in. 
\+
\ \ \ \ \ \ \ Cheap. You can do it yourself.\,
\+
\,
\+
\,
\+
 G. Intelligent strategies for dealing with radon.\,
\+
\,
\+
\ \ \ \ The first need is to assess the \ problem. \  In \ Pennsylvania, \ one 
\+
\ \ \ \ house had about 1000 times the EPA standard of 4 pCi/L. The estim-\A
\+
\ \ \ \ ated dose would be about 45 \4REM\1/yr from breathing \ this \ (assuming 
\+
\ \ \ \ one was in the house about 12 hrs/day). The chance of getting lung 
\+
\ \ \ \ cancer from this is about 25 times that of \ getting \ killed \ in \ a 
\+
\ \ \ \ car. It cost about $32,000 to reduce the radon level in this house 
\+
\ \ \ \ to the EPA standard. \,
\+
\,
\+
\ \ \ \ Very few houses have anything like such a \ severe \ problem. \  Most 
\+
\ \ \ \ homes in Virginia have levels in the range \ 1.6-2.5 \ pCi/L. \ About 
\+
\ \ \ \ 13% have levels in the range 4-20.  Less than 1% have levels above 
\+
\ \ \ \ 20 pCi/L.\,
\+
\,
\+
\ \ \ \ Since the tests are cheap, and will soon be mandated by \ law \ (for 
\+
\ \ \ \ no reason that I can understand based on actual \ hazard), \ perhaps 
\+
\ \ \ \ you should have one done. \ Call \ 1-800-468-0138 \ (State \ Dep't \ of 
\+
\ \ \ \ Health Radon Hotline) for more information.\,
\+
\,
\+
\ \ \ \ When should you worry? In my opinion, you should \ worry \ when \ the 
\+
\ \ \ \ risk is equal to that of dying in a car crash. For a \ smoker \ this 
\+
\ \ \ \ means when the radon level is about 100 pCi/L in his home.  For \ a 
\+
\ \ \ \ non-smoker, the permissible level may be higher. \,
\+
\,
\+
\ \ \ \ Assume the radon level is 8 pCi/L. Would you rather spend $500 \ on 
\+
\ \ \ \ getting the level down to 4 pCi/L (keep in mind that Britain \ sets 
\+
\ \ \ \ the OK level at 10 pCi/L) or on an airbag restraint system on your 
\+
\ \ \ \ car?  I would say, "Based on the maximum possible hazard, put \ the 
\+
\ \ \ \ money into the car safety."\,
\+
\,
\+
\,
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\ \ \ \ In conclusion: \,
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\,
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\ \ \ \[\6> \1Large amounts of radiation are definitely not good for you.\,
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\,
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\ \ \ \[\6> \1There is \!no \1evidence that low-level radiation, comparable to the 
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\ \ \ \ \ \ natural background you cannot avoid, has \ any \ effect \ whatever. 
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\,
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\ \ \ \[\6> \1But taking the most pessimistic extrapolation, low-level \ radia-\A
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\ \ \ \ \ \ tion like that from the average radon content of a home is \ much 
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\ \ \ \ \ \ less dangerous to you than other hazards you routinely accept.\,
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\,
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\ \ \ \[\6> \1Check your radon. If it isn't excessive, don't worry, be happy!\,
\=