United States
Environmental Protection
Agency
Air and Radiation
(6604J)
402-R-93-037
September 1993
EPA's Map of Radon Zones

KENTUCKY
                                            Recycled/Recyclable
                                            Printed on paper that contains
                                            at least 50% recycled fiber

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       EPA'S MAP OF RADON ZONES
               KENTUCKY
             RADON DIVISION
  OFFICE OF RADIATION AND INDOOR AIR
U.S. ENVIRONMENTAL PROTECTION AGENCY
             SEPTEMBER, 1993

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                              ACKNOWLEDGEMENTS
       This document was prepared by the U.S. Environmental Protection Agency's (EPA's)
Office of Radiation and Indoor Air (ORIA) in conjunction with the U.S. Geological Survey
(USGS).. Sharon W.  White was the EPA project manager.  Numerous other people in ORIA
were instrumental in the development of the Map of Radon Zones, including Lisa Ratcliff,
Kirk Maconaughey, R. Thomas Peake, Dave Rowson, and Steve Page.

       EPA would especially like to acknowledge the outstanding effort of the USGS
radon team — Linda Gundersen, Randy Schumann, Jim Otton, Doug Owen, Russell
Dubiel, Kendell Dickinson, and Sandra Szarzi ~ in developing the technical base for the
Map of Radon Zones.

       ORIA  would also like to recognize the efforts of all the EPA Regional Offices in
coordinating the reviews with the State programs and the Association of American State
Geologists (AASG) for providing a liaison with the State geological  surveys.  In addition,
appreciation is expressed to all of the State radon programs and geological surveys for their
technical input and review of the Map of Radon Zones.

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            TABLE OF CONTENTS
               I. OVERVIEW
     II. THE USGS/EPA RADON POTENTIAL
        ASSESSMENTSiINTRODUCTION
  III. REGION 4 GEOLOGIC RADON POTENTIAL
                SUMMARY
V. PRELIMINARY GEOLOGIC RADON POTENTIAL
         ASSESSMENT OF KENTUCKY
 V. EPA'S MAP OF RADON ZONES -- KENTUCKY

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                                     OVERVIEW
       Sections 307 and 309 of the 1988 Indoor Radon Abatement Act (IRAA) direct EPA to
identify areas of the United States that have the potential to produce elevated levels of radon.
EPA, the U.S. Geological  Survey (USGS), and the Association of American State Geologists
(AASG) have worked closely over the past several years to produce  a series of maps and
documents which address these directives. The EPA Map of Radon  Zones is a compilation of
that work  and fulfills the requirements of sections 307 and 309 of IRAA.  The Map of Radon
Zones identifies, on a county-by-county basis, areas of the U.S. that have the highest potential
for elevated indoor radon levels (greater than 4 pCi/L).
       The Map of Radon Zones is designed to assist national, State and local governments
and organizations to target their radon program activities and resources. It is also intended to
help building code officials determine areas that are the highest priority for adopting radon-
resistant building practices.  The Map of Radon Zones should not be used to determine if
individual homes in any given area need to be  tested for radon.  EPA recommends that all
homes be tested  for radon, regardless of geographic location or the zone designation of
the county in which they are located.
       This document provides background information concerning the development of the
Map of Radon Zones.  It explains the purposes of the map, the approach for developing  the
map (including the respective roles of EPA and USGS), the data sources used, the conclusions
and confidence levels  developed for the prediction of radon potential, and  the review process
that was conducted to finalize this effort.

BACKGROUND

       Radon (Rn222) is a colorless, odorless, radioactive gas.  It comes from the natural
decay of uranium that is found in nearly all soils.  It typically moves through the ground to
the air above and into homes and other buildings through cracks and openings in the
foundation.  Any  home, school or workplace may  have a radon problem, regardless  of
whether it is new or old, well-sealed  or drafty,  or with or without a basement.  Nearly one out
of every 15  homes in  the U.S.  is estimated to have elevated annual average levels of indoor
radon.
       Radon first gained national attention in  early  1984, when extremely high levels of
indoor radon were found in areas of Pennsylvania, New Jersey, and New York, along the
Reading Prong-physiographic province. EPA established a Radon Program in 1985  to assist
States and homeowners in reducing their  risk of lung cancer from indoor radon.
       Since 1985, EPA and USGS have been  working together to continually increase our
understanding of radon sources and the migration dynamics that cause elevated indoor radon
levels.  Early efforts resulted in the  1987  map entitled "Areas with Potentially High Radon
Levels." This map was based on limited  geologic information only because few indoor radon
measurements were available at the time.  The  development of EPA's Map of Radon Zones
and its technical  foundation, USGS1 National Geologic Radon Province Map,  has been based
on additional information from six years of the State/EPA Residential Radon  Surveys,
independent State residential surveys, and continued  expansion of geologic and geophysical
information, particularly the data from the National Uranium Resource Evaluation project.
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 Purpose of the Map of Radon Zones

       EPA's Map of Radon Zones  (Figure 1) assigns each of the 3141 counties in the
 United States to one of three zones:

              o      Zone 1 counties have a predicted average indoor screening level > than
                     4 pCi/L

              o  ••   Zone 2 counties have a predicted average screening level > 2 pCi/L and
                     < 4 pCi/L

              o      Zone 3 counties have a predicted average screening level < 2 pCi/L

       The Zone designations were determined by assessing five factors that are known to be
 important indicators of radon potential: indoor radon measurements, geology, aerial
 radioactivity, soil parameters, arid foundation types.
       The predictions of average screening levels in each of the Zones  is an expression of
 radon potential in  the lowest liveable area of a structure.  This map is unable to estimate
 actual  exposures to radon.  EPA recommends methods for testing and fixing individual homes
 based on an estimate of actual exposure to radon.  For more information on testing and fixing
 elevated  radon levels in homes consult these EPA publications: A Citizen's Guide to Radon.
 the Consumer's Guide to Radon Reduction and the Home Buyer's and Seller's Guide to
 Radon.
       EPA believes that States, local governments and other organizations can  achieve
 optimal risk reductions by targeting resources and program activities to high radon potential
 areas.  Emphasizing targeted approaches (technical assistance, information and outreach
 efforts, promotion of real estate mandates and policies and building codes, etc.)  in such areas
 addresses the greatest potential risks  first.
       EPA also believes that the use of passive radon control systems in the construction of
 new homes in Zone 1 counties, and the activation of those systems if necessitated by follow-
 up testing,  is a cost effective approach to achieving significant radon risk reduction.
       The Map of Radon Zones and its supporting documentation establish no  regulatory
 requirements.  Use of this map by State or local radon programs and building code officials is
 voluntary.  The information presented on the Map of Radon Zones and in the  supporting
 documentation is not applicable to radon in water.

 Development of the Map of Radon Zones

       The technical foundation for the Map of Radon Zones is the USGS Geologic Radon
 Province Map. In order to examine the radon potential for the United States, the USGS
 began by identifying approximately  360 separate geologic provinces for  the U.S. The
provinces are shown on the USGS Geologic Radon Province Map (Figure 2).  Each of the
geologic provinces was evaluated by examining the available data for that area:  indoor radon
 measurements, geology, aerial radioactivity, soil parameters, and foundation types.  As stated
previously, these five factors are considered  to be of basic importance in assessing radon
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potential and some data are available for each of these factors in every geologic province. The
province boundaries  do not coincide with political borders (county and:state) but define areas
of general radon potential.  The five factors were assigned numerical values based on an
assessment of their respective contribution to radon potential, and a confidence level was
assigned to each contributing variable.  The approach used by USGS to estimate the radon
potential for each province is described in Part II of this document.
       EPA subsequently developed the Map of Radon Zones by extrapolating from the
province level to the county level so that all counties in the  U.S. were assigned to one of
three radon zones. EPA  assigned each county to a given zone based on its provincial radon
potential.. For example, if  a county is located within a geologic province that has a predicted
average screening level greater than 4 pCi/L, it was assigned to Zone 1.  Likewise, counties
located in provinces  with predicted average screening levels > 2 pCi/L and < 4 pCi/L, and
less than 2 pCi/L, were assigned to Zones 2 and 3, respectively.
       If the boundaries  of a county fall in more than one geologic province,  the county was
assigned to a zone based on the predicted radon potential of the province in which most of
the area lies.  For example, if three different provinces cross through a given county, the
county was assigned to the zone representing the radon potential of the province containing
most of the county's land area.  (In this case, it is  not technically correct to say that the
predicted average screening level applies to the entire county since the county falls in
multiple.provinces with differing radon potentials.)
       Figures 3 and 4 demonstrate an example of how EPA extrapolated the county zone
designations for Nebraska from the USGS geologic province map for the State.  As figure 3
shows, USGS has identified 5 geologic provinces for Nebraska.  Most of the counties are
extrapolated "straight"  from their corresponding provinces, but there are counties "partitioned"
by several provinces — for example, Lincoln County.  Although Lincoln county falls in
multiple provinces, it was assigned to Zone 3 because most  of its area falls in the province
with the lowest radon  potential.
       It is important to note that EPA's extrapolation from the province level to the
county level  may mask  significant "highs" and  "lows" within specific counties.  In other
words, within-county variations in radon potential are not shown on the Map of Radon
Zones. EPA recommends that users who may need to address specific within-county
variations in radon potential  (e.g., local government officials considering the
implementation of radon-resistant construction codes) consult USGS' Geologic Radon
Province Map and  the State chapters provided  with this map for more detailed
information, as well as  any locally available data.

Map Validation

       The Map of Radon Zones is intended to represent a  preliminary assessment of radon
potential for the entire United States.   The factors that are used in this effort —indoor radon
data, geology, aerial radioactivity, soils, and foundation type — are basic indicators for radon
potential. It  is important to note, however, that the map's county zone designations are not
"statistically valid" predictions due to the nature of the data available for these 5 factors at the
county level.  In order to validate the map in light of this lack of statistical confidence, EPA
conducted a number of analyses.  These analyses have helped EPA to identify the best
situations in which to  apply the map, and its limitations.
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Figu're 3
                 Geologic  Radon  Potential  Provinces  for  Nebraska
         Lincoln County
           Bilk       Hoi trite      Low
Figure 4
         NEBRASKA  -  EPA  Map  of Radon Zones
        Li a c o 1 a County
         Zoae 1     Zoae 2    Zone 3
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       One such analysis involved comparing county zone designations to indoor radon
measurements from the State/EPA Residential Radon Surveys (SRRS).  Screening  averages
for counties with at least 100 measurements were compared to the counties' predicted radon
potential as indicated by the Map of Radon Zones.  EPA found that 72% of the county
screening averages were correctly reflected by the appropriate zone designations on the Map.
In all other cases, they only differed by 1  zone.
       Another accuracy analysis used the annual average data from the National Residential
Radon Survey (NRRS). The NRRS indicated that approximately 6 millio"n homes in the
United States have annual averages greater than or equal to 4 pCi/L.  By cross checking the
county location of the approximately 5,700 homes which participated in_the survey, their
radon measurements, and the zone designations  for these counties, EPA found that
approximately 3.8  million homes of the 5.4 million  homes with radon levels greater than or
equal to 4 pCi/L will be found in counties designated as Zone  1. A random sampling  of an
equal number of counties would have only found approximately 1.8 million homes greater
than 4 pCi/L.  In other words, this analysis indicated that the map approach is three times
more efficient at identifying high radon areas than random selection of zone designations.
       Together, these analyses' show  that the approach EPA used to develop the Map  of
Radon Zones is a reasonable one.  In  addition, the Agency's confidence is enhanced by results
of the extensive State review process — the map generally agrees with the States' knowledge
of and experience in their own jurisdictions. However, the accuracy analyses highlight two
important points:  the fact that elevated levels will be found in Zones 2 and 3, and that there
will be significant  numbers of homes  with lower indoor radon  levels in all of the Zones.  For
these reasons, users of the Map of Radon Zones need to supplement the Map with locally
available data whenever possible.  Although all  known  "hot spots", i.e., localized areas of
consistently  elevated levels, are discussed  in the State-
specific chapters, accurately defining the boundaries of the "hot spots" on this scale of map is
not possible at this time.  Also, unknown  "hot spots" do exist.
       The Map of Radon Zones is intended to  be a starting point for characterizing radon
potential because our knowledge of radon  sources and transport is always growing. Although
this effort represents the best data available at this time, EPA will continue to study these
parameters and others such as house construction, ventilation features and meteorology factors
in order to better characterize the presence of radon in U.S homes, especially in high risk
areas.  These efforts will eventually assist EPA  in refining and revising the conclusions of the
Map of Radon Zones.  And although this  map is most appropriately used as a targeting tool
by the aforementioned audiences — the Agency encourages all residents to test their homes
for radon, regardless  of geographic  location or the zone designation  of the county in
which they  live.  Similarly, the Map of Radon Zones should not to be used in lieu of
testing during real estate transactions.

Review Process

       The Map of Radon Zones has  undergone extensive review within EPA and outside the
Agency.  The Association of American State Geologists (AASG) played an integral role in
this review process.  The AASG individual State geologists have reviewed their State-specific
information, the USGS Geologic Radon Province Map, and other materials for their geologic
content and  consistency.
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       In addition to each State geologist providing technical comments, the State radon
offices were asked to comment on their respective States' radon potential evaluations. In
particular, the States were asked to evaluate the data used to assign their counties to specific
zones. EPA and USGS worked with the States to resolve any issues concerning county zone
 lejgnalions.   In a few cases, States have requested  .hanges in coonty  zone designations.  The.
requests were based on additional data from the State on geology, indoor radon
measurements, population, etc.  Upon reviewing the data submitted by the  States, EPA did
make some changes in  zone designations.  These changes, which  do not strictly follow the
methodology  outlined in this document, are discussed in the respective State chapters.
       EPA encourages the States and counties to conduct further research and data collection
efforts to refine the Map of Radon Zones.  EPA would like to be kept informed of any
changes the States, counties, or others make to the maps.  Updates and revisions will be
handled in a similar fashion to the way the map was developed.  States should notify EPA of
any proposed  changes by forwarding the changes through the Regional EPA offices that are
listed in Part  II.  Depending on the amount of new information that is presented, EPA will
consider updating this map periodically. The State radon programs should initiate proper
notification of the appropriate State officials when the Map of Radon Zones is released  and
when revisions or  updates are made by the State or  EPA.
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    THE USGS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
                                           by
                     Linda C.S. Gundersen and R. Randall Schumann
                                  U.S. Geological Survey
                                           and
                                    Sharon W. White
                           U.S. Environmental Protection Agency

BACKGROUND

    The Indoor Radon Abatement Act. of 1988 (15 U.S.C. 2661-2671) directed the U.S.
Environmental Protection  Agency (EPA) to identify areas of the United States that have the
potential to produce harmful levels  of indoor radon.  These characterizations were to be based
on both geological data and on. indoor radon  levels in homes and other structures.  The EPA
also was directed to develop model standards and techniques for new building construction
that would provide  adequate prevention or mitigation of radon entry.  As part  of an
Interagency Agreement between the EPA and the U.S.  Geological Survey (USGS), the USGS
has prepared  radon  potential estimates for the United States. This report is one of ten
booklets that document this effort.  The purpose and intended use of these reports is to help
identify areas where states can  target  their radon program resources, to provide guidance in
selecting the  most appropriate building code options for areas, and to provide general
information on radon and geology for each state for federal, state, and municipal officials
dealing with  radon  issues.  These reports are not intended to be used as a substitute for
indoor radon testing, and they  cannot and should not be used to estimate or predict the   .
indoor radon concentrations of individual homes, building sites, or housing tracts.   Elevated
levels of indoor radon have been found in every State,  and EPA recommends that all homes
be tested for indoor radon.
    Booklets detailing the radon potential assessment for the U.S. have been developed for
each State. USGS  geologists are the  authors of the geologic radon potential booklets.  Each
booklet consists of  several components, the first being an overview to the mapping  project
(Part I),  this  introduction  to the USGS assessment (Part II), including a general discussion of
radon (occurrence,  transport, etc.), and details concerning the types of data used.  The third
component is a  summary  chapter outlining the general geology and geologic radon  potential
of the  EPA Region (Part III).  The fourth component is an individual chapter  for each state
(Part IV). Each state chapter discusses the state's specific geographic setting,  soils, geologic
setting, geologic radon  potential, indoor radon data, and  a summary outlining the radon
potential rankings of geologic areas in the state.  A variety of maps "are presented in each
chapter—geologic,  geographic, population, soils, aerial radioactivity, and indoor radon data by
county.  Finally, the booklets contain EPA's  map of radon zones for each state and an
accompanying description (Part V).
    Because of constraints on the scales of maps presented in these reports and because  the
smallest units used to present the indoor radon data are counties, some generalizations have
been   made  in order to estimate the radon potential of each area. Variations in geology, soil
characteristics, climatic factors, homeowner lifestyles,  and other factors that influence radon
concentrations can  be quite large within any particular geologic area, so these reports cannot
be  used to estimate or predict the indoor radon concentrations  of individual homes or housing

                                            II-l     Reprinted from USGS Open-File Report 93-292

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tracts.  Within any area of a given geologic radon potential ranking, there are likely to be
areas where the radon potential is lower or higher than that assigned to the area as a whole,
especially in larger areas such as the large counties in some western states.
    In  each state chapter, references to additional reports related to radon are listed for the
Mate, and the reader is urged to consult these reports for more detailed information.  In most
cases the best sources of information on radon for specific areas are state and local
departments of health, state departments responsible for nuclear safety or environmental
protection, and U.S. EPA regional offices. More detailed information on state or local
geology may be obtained from the state geological surveys.  Addresses and telephone
numbers of state radon contacts, geological surveys, and EPA regional offices are listed in
Appendix C at the end of this chapter.

RADON GENERATION AND TRANSPORT IN  SOILS

    Radon (252Rn) is produced from the radioactive decay of radium (226Ra), which is, in turn,
a product of the decay of uranium (238U) (fig. 1).  The half-life pf -2Rn is 3.825 days. Other
isotopes of radon occur naturally, but, with the exception of thoron ("°Rn), which occurs in
concentrations high enough to be of concern in a few localized areas, they are less important
in terms of indoor radon risk because of their extremely short half-lives and less common
occurrence. In general, the concentration and mobility of radon  in soil are dependent on
several factors, the most important of which  are the soil's radium content and distribution,
porosity, permeability to gas movement, and moisture content.  These characteristics are, in
turn, determined by the soil's parent-material composition, climate, and the soil's age or
maturity.  If parent-material  composition, climate, vegetation, age of the soil, and topography
are known, the physical and chemical properties of a soil in  a given area can be predicted.
    As soils form, they develop distinct layers, or horizons, that are cumulatively called the
soil profile.  The A horizon  is a surface or near-surface horizon  containing a relative
abundance of organic matter but dominated by mineral matter.  Some soils contain an E
horizon, directly below the A horizon, that is generally characterized by loss of clays, iron, or
aluminum, and has a characteristically lighter color than the A horizon.  The B horizon
underlies the A  or E  horizon. Important characteristics of B horizons include accumulation of
clays, iron oxides, calcium carbonate or other soluble salts, and organic matter complexes.  In
drier environments, a horizon may exist within or below the B horizon that is dominated by
calcium carbonate, often called caliche or calcrete. This carbonate-cemented horizon is
designated the K horizon in  modern soil classification schemes.  The C  horizon underlies the
B (or K) and is a zone of weathered parent material  that does not exhibit characteristics of A
or B horizons; that is, it is generally not a zone of leaching or accumulation. In soils formed
in place from the underlying bedrock, the C horizon  is a zone of unconsolidated, weathered
bedrock overlying the unweathered bedrock.
    The shape and orientation of soil particles (soil structure) control permeability and affect
water movement in the soil. Soils with blocky or granular structure have roughly equivalent
permeabilities in the  horizontal and  vertical directions, and air and water can infiltrate the soil
relatively easily.  However, in soils  with platy structure, horizontal permeability is much
greater than vertical permeability, and air and moisture infiltration is generally slow.  Soils
with prismatic or columnar structure have dominantly vertical permeability. Platy and
prismatic structures form in  soils with high clay contents. In soils with shrink-swell clays, air


                                            II-2     Reprinted from USGS Open-File, Report 93-292

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and moisture infiltration rates and depth of wetting may be limited when the cracks in the
surface soil layers swell shut. Clay-rich B horizons, particularly those with massive or platy
structure, can form a capping layer that impedes the  escape of soil gas to the surface
(Schumann and others,  1992). However, the shrinkage of clays can act to open or widen
cracks upon drying, thus increasing the soil's permeability to gas flow during drier periods.
       Radon transport  in soils occurs by  two processes: (1) diffusion and (2) flow (Tanner,
1964). Diffusion is the process whereby radon atoms move from areas of higher
concentration to areas of lower concentration "in response to a concentration gradient.  Flow is
the process by which soil  air moves through soil pores in response to differences in pressure
within the  soil or between the soil and the atmosphere, carrying the radon atoms along with it.
Diffusion is the dominant radon transport  process in  soils of low permeability, whereas flow
tends to dominate in highly  permeable soils  (Sextro and others, 1987).  In low-permeability
soils, much of the radon may decay before it is able to enter a building because its transport
rate is reduced.  Conversely, highly permeable soils,  even those that are relatively low in
radium, such as those derived from some types of glacial deposits, have been associated with
high indoor radon levels in Europe and in the northern United States (Akerblom and others,
1984; Kunz and others,  1989; Sextro and others, 1987).  In areas of karst topography formed
in carbonate rock (limestone or dolomite)  environments, solution cavities and fissures can
increase soil permeability  at depth by providing additional pathways for gas flow.
    Not all radium contained in soil grains and grain coatings will result in mobile radon
when the radium  decays.  Depending on where the radium is distributed in the soil, many of
the radon atoms may remain imbedded in  the soil grain containing the parent radium atom, or
become imbedded in adjacent soil grains.  The portion  of radium that releases radon into the
pores and fractures of rocks and soils is called the emanating  fraction.  When a radium atom
decays to radon, the energy  generated is strong enough to send the radon atom a distance of
about 40 nanometers (1  nm  = 10'9 meters), or about 2xlO'6 inches—this is  known as alpha
recoil (Tanner, 1980).  Moisture in the soil lessens the  chance of a recoiling radon atom
becoming imbedded in an adjacent grain.  Because water is more dense than air,  a radon atom
will travel  a shorter distance in a water-filled pore than in an  air-filled pore, thus increasing
the likelihood that the radon atom will remain in the pore space.  Intermediate moisture levels
enhance radon emanation but do not significantly affect permeability. However,  high
moisture levels can significantly decrease the gas permeability of the soil and impede radon
movement  through the soil.
    Concentrations of radon in soils are generally  many times higher than those inside  of
buildings, ranging from tens of pCi/L to more than 100,000 pCi/L, but typically in the range
of hundreds to low thousands of pCi/L. Soil-gas radon concentrations can vary in response to
variations in climate and weather on hourly, daily, or seasonal time scales. Schumann  and
others (1992) and Rose  and others (1988) recorded order-of-magnitude variations in soil-gas
radon concentrations between seasons in Colorado and Pennsylvania. The most important
factors appear to  be (1) soil moisture conditions, which are controlled in large part by
precipitation; (2)  barometric pressure; and (3) temperature. Washington and Rose (1990)
suggest that temperature-controlled partitioning of radon  between water and gas in soil pores
also has a significant influence on the amount of mobile radon in soil gas.
    Homes in hilly limestone regions of the southern Appalachians were found to have higher
indoor radon concentrations during the summer than in the winter.  A suggested  cause for this
phenomenon involves temperature/pressure-driven flow of radon-laden  air from subsurface


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solution cavities in the carbonate rock "into houses. As warm air enters solution cavities that
are higher on the hillslope than the homes, it cools and settles, pushing radon-laden air from
lower in the cave or cavity system into structures on  the hillslope (Gammage and others,
1993). In contrast, homes built over caves having openings situated below the level of the
home had higher indoor radon levels in the wintei, caused by cooler outside air entering the
cave, driving radon-laden air into  cracks and solution cavities in the rock and soil, and
ultimately, into homes (Gammage and others, 1993).

RADON ENTRY INTO BUILDINGS

    A driving force (reduced atmospheric pressure in the house relative to the soil, producing
a pressure gradient) and entry points must exist for radon to enter a building from the soil.
The negative pressure caused by furnace combustion, ventilation devices, and the  stack effect
(the rising and escape of warm air from the  upper floors of the building,  causing  a
temperature and pressure gradient within the structure) during cold winter months are
common driving forces.  Cracks and other penetrations through building foundations, sump
holes, and slab-to-foundation wall joints are  common entry  points.
    Radon levels in the basement  are generally higher than  those on the main floor or upper
floors of most structures. Homes  with basements generally provide more entry points for
radon, commonly have a more pronounced stack effect, and typically have lower  air pressure
relative to the surrounding soil than nonbasement homes.  The term "nonbasement"  applies to
slab-on-grade or crawl space construction.

METHODS AND  SOURCES  OF  DATA

    The assessments of radon potential in the booklets that  follow this introduction were
made using five main types of data: (1) geologic (lithologic); (2) aerial radiometric; (3)  soil
characteristics, including soil moisture, permeability, and drainage characteristics;  (4) indoor
radon data;  and (5) building architecture (specifically, whether homes in each area are built
slab-on-grade or have a basement  or crawl space). These five factors were evaluated and
integrated to produce estimates of radon potential.  Field measurements of soil-gas radon or
soil radioactivity were not used except where such data were available in existing, published
reports of local field studies.  Where applicable, such field studies are described in the
individual state chapters.

GEOLOGIC DATA

    The types and distribution of lithologic units and other  geologic features in an
assessment area are of primary importance in determining radon potential.  Rock  types that
are most likely to cause  indoor radon problems include carbonaceous black shales, glauconite-
bearing sandstones, certain kinds of fluvial sandstones and fluvial sediments, phosphorites,
chalk, karst-producing carbonate rocks, certain  kinds  of glacial deposits, bauxite, uranium-rich
granitic rocks, metamorphic rocks of granitic composition, silica-rich volcanic rocks, many
sheared or faulted rocks, some coals, and certain kinds of contact metamorphosed rocks.
Rock types  least likely to cause radon problems include marine quartz sands, non-
carbonaceous shales and siltstones, certain kinds of clays, silica-poor metamorphic and


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igneous rocks, and basalts.  Exceptions exist within these general litholbgic groups because of
the occurrence of localized uranium deposits, commonly of the hydrothermal type in
crystalline rocks or the "roll-front" type in sedimentary rocks. Uranium and radium are
commonly sited in heavy minerals, iron-oxide coatings on rock and soil grains, and organic
materials in  soils and sediments.  Less common are uranium associated with phosphate and
carbonate complexes in rocks and soils, and uranium minerals.
    Although many cases of elevated indoor radon levels can be traced to  high radium and
(or) uranium concentrations in parent rocks, some structural features, most notably faults and
shear zones, have been identified as sites of localized uranium concentrations (Deffeyes and
MacGregor,  1980) and have been associated with some of the highest reported indoor radon
levels (Gundersen, 1991).  The two highest known indoor radon occurrences are associated
with sheared fault zones in Boyertown, Pennsylvania (Gundersen and others,  1988a; Smith
and others, 1987), and in Clinton, New Jersey (Henry and others, 1991; Muessig  and Bell,
1988).

MURE AERIAL  RADIOMETRIC DATA

    Aerial radiometric data are used to quantify the radioactivity of rocks and soils.
Equivalent uranium (eU) data provide an estimate of the surficial concentrations of radon
parent materials (uranium, radium) in rocks and soils. Equivalent  uranium is calculated from
the counts received by a gamma-ray detector from the 1.76 MeV (mega-electron  volts)
emission energy corresponding to bismuth-214 (2HBi), with the assumption  that uranium and
its decay products are in secular equilibrium. Equivalent uranium is expressed in units of
parts per million (ppm).  Gamma radioactivity also may be expressed in terms  of a radium
activity; 3 ppm eU corresponds to approximately 1 picocurie  per gram  (pCi/g)  of radium-226.
Although radon is highly mobile in soil and its concentration  is affected by meteorological
conditions (Kovach,  1945; Klusman and Jaacks, 1987; Schery and others, 1984; Schumann
and others, 1992), statistical correlations between average soil-gas  radon concentrations and
average eU values for a wide variety of soils have been documented (Gundersen  and others,
1988a, 1988b; Schumann and Owen, 1988).  Aerial radiometric data can provide  an estimate
of radon source strength over a region, but the amount of radon that is able to enter a home
from the soil is dependent on several local  factors, including soil structure, grain  size
distribution,  moisture content,  and permeability, as well as type of house construction and its
structural condition.
    The aerial radiometric data used for these characterizations were  collected as part of the
Department  of Energy National Uranium Resource Evaluation (NURE) program of the 1970s
and early 1980s.  The purpose of the NURE program was to  identify and describe areas  in the
United States having potential uranium resources (U.S. Department of Energy,  1976).  The
NURE aerial radiometric data were collected by  aircraft in which a gamma-ray spectrometer
was mounted, flying approximately 122 m (400 ft) above  the ground surface.   The equivalent
uranium maps presented in the state chapters were generated  from reprocessed NURE data in
which smoothing, filtering, recalibrating, and matching of adjacent quadrangle  data sets were
performed to compensate for background, altitude, calibration, and other types of errors and
inconsistencies  in the original  data set (Duval and others, 1989).  The data were then gridded
and contoured to produce maps of eU with a pixel size corresponding to approximately 2.5 x
2.5 km (1.6  x 1.6 mi).

                                           II-6     Reprinted from USGS Open-File Report 93-292

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                  F11C11T  LINE  SPACING  OF NUKE  AERIAL  SURVEYS
                     2 k'U  (1  KILE]
                     5 KM  (3  MILES)
                     2 fc 5  O
                 E3 10 £U  {6 HUES)
                     5 k 10  KM
                     NO DATA
Figure 2. Nominal flightline spacings for NURE aerial gamma-ray surveys covering the
contiguous United States (from Duval and others, 1990).  Rectangles represent I°x2° quadrangles.

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    Figure 2 is an index map of NUKE 1° x 2° quadrangles showing the flight-line spacing
for each quadrangle.  In general, the more closely spaced the flightlines are, the more area
was covered by the aerial gamma survey, and thus, more detail is available in the data set.
For an altitude of 400 ft above the ground surface and with primary flightline spacing
typically between 3 and 6 miles, less than 10 percent of the ground surface of the United
States was actually measured by the airborne gamma-ray detectors (Duval and others, 1989),
although some areas had better coverage than others due to the differences in flight-line
spacing between  areas (fig. 2).   This suggests that some  localized uranium anomalies may not
have been detected by the aerial surveys,  but the good correlations of eU patterns with
geologic outcrop  patterns indicate  that, at relatively small scales (approximately 1:1,000,000
or smaller) the National eU map (Duval and others, 1989) gives reasonably good estimates of
average surface uranium concentrations and thus can assist in the prediction of radon potential
of rocks and soils, especially when augmented with  additional geologic and soil data.
    The shallow  (20-30 cm)  depth  of investigation of gamma-ray spectrometers, either
ground-based or airborne (Duval and others, 1971; Durrance,  1986), suggests that gamma-ray
data may sometimes underestimate the radon-source strength in soils in which some of the
radionuclides in  the near-surface soil  layers have been transported downward through the soil
profile,  In such cases the concentration of radioactive minerals in the  A horizon would be
lower than in the B horizon,  where such minerals are typically concentrated.  The
concentration of radionuclides in the C  horizon and  below may be relatively  unaffected by
surface  solution processes.  Under these conditions the surface gamma-ray signal may indicate
a lower radon source concentration than actually exists in the deeper soil  layers, which are
most likely  to affect radon levels in structures with basements. The redistribution of
radionuclides in  soil profiles is dependent on a combination of climatic, geologic, and
geochemical factors.  There is reason to believe that correlations  of eU with actual soil
radium  and uranium concentrations at a depth relevant to radon entry into structures may be
regionally variable  (Duval, 1989; Schumann and Gundersen, 1991). Given sufficient
understanding of the factors  cited above, these regional differences may be predictable.

SOIL SURVEY DATA

    Soil surveys  prepared by the U.S. Soil Conservation Service  (SCS) provide data on soil
characteristics, including soil-cover thickness, grain-size  distribution, permeability, shrink-
swell potential, vegetative cover, generalized groundwater characteristics, and land use.  The
reports  are available in county formats and State summaries.  The county reports typically
contain  both generalized and detailed maps of soils in the area.
    Because of time and map-scale constraints, it was impractical to examine county soil
reports  for each county in the United States, so  more generalized summaries at appropriate
scales were used  where available.   For State or regional-scale radon characterizations, soil
maps were compared to geologic maps  of the area, and the soil descriptions, shrink-swell
potential, drainage characteristics,  depth to seasonal high water table, permeability, and other
relevant characteristics of each soil group noted. Technical soil terms used in soil surveys are
generally complex; however, a good summary of soil engineering terms and the national
distribution of technical soil  types is the "Soils" sheet of the National Atlas (U.S. Department
of Agriculture, 1987).
                                           II-8     Reprinted from USGS Open-File Report 93-292

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    Soil permeability is commonly expressed in SCS soil surveys m terms of the speed, m
inches per hour (in/hr), at which water soaks into the soil, as measured m a soil  percolation
test  Although in/hr are not truly units of permeability, these units are in widespread use and
are'referred to as "permeability" in SCS soil surveys.  The permeabilities hsted in the SCS
surveys are for water, but they generally correlate well with gas permeability.  Because data
on gas permeability of soils is extremely limited, data on permeability to water is used as a
substitute-except in cases  in which excessive soil moisture is known to exist  Water in soil
pores inhibits gas transport, so the amount of radon available to a home is effectively reduced
by a high water  table.  Areas likely to have high water tables include river valleys, coastal
areas, and  some areas overlain by deposits of glacial origin (for example loess).
    Soil permeabilities greater than 6.0 in/hr may be considered high, and permeabilities less
than 0 6 in/hr may be considered low in terms  of soil-gas transport. Soils with low
permeability may generally be considered to have a lower radon potential than more
permeable soils  with similar radium concentrations.  Many well-developed sods contain a
clay-rich B horizon that may impede vertical soil gas transport.  Radon generated  below this
horizon  cannot readily escape to the surface, so it would instead tend to move laterally,
especially  under the influence of a negative pressure exerted by a building.
     Shrink-swell potential is an indicator of the abundance of smectitie (swelling) clays in a
 soil  Soils with a high shrink-swell potential may cause building foundations to crack,
 creating pathways for radon entry into the structure.  During dry periods, desiccation cracks in
 shrink-swell soils provide additional pathways for soil-gas transport and effectively increase
 the gas  permeability of the soil. Soil permeability data and  soil profile data thus  prov.de
 important information for regional radon assessments.

 INDOOR RADON DATA

     Two major sources of indoor radon data were used.  The first and largest source of data is
 from the  State/EPA Residential Radon Survey (Ronca-Battista and others, 1988; Dziuban and
 others  1990). Forty-two states completed EPA-sponsored indoor radon surveys between 1986
 and 1992 (fig 3)  The State/EPA Residential Radon Surveys were designed to be
 comprehensive and statistically significant at the state level, and were subjected to high levels
 of quality assurance and control. The surveys collected screening indoor radon measurements,
 defined as 2-7  day measurements using charcoal canister radon detectors placed in the lowest
 livable area of the home.  The target population for the surveys included owner-occupied
 single family, detached housing units (White  and others, 1989), although attached structures
 such as duplexes, townhouses, or condominiums were included in some of the surveys if they
  met the other criteria and had contact with the ground surface.  Participants  were selected
  randomly from telephone-directory listings.  In total, approximately 60,000 homes were tested
  in the State/EPA surveys.
      The  second source of indoor radon data comes from residential surveys that have been
  conducted in a specific state or region of the country (e.g. independent state surveys or utility
  company surveys).  Several states, including  Delaware, Florida, Illinois. New Hampshire,  New
  Jersey New York, Oregon,  and Utah, have conducted their own surveys of indoor radon  The
  quality and design of a state or other independent survey are discussed and  referenced where
  the data are used.


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 ex
 60


H
 
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    Data for only those counties with five or more measurements are shown in the indoor
radon maps in the state chapters,  although data for all counties with a nonzero number of
measurements are listed in the indoor radon data tables in each state chapter.  In total, indoor
radon data from more than 100,000 homes nationwide were used in the compilation of these
assessments. Radon data from State or regional indoor radon surveys, public health
organizations, or other sources are discussed in addition to the primary data sources where
they are available.  Nearly all of the data used in these evaluations  represent short-term (2-7
day) screening measurements from the lowest livable space of the homes.  Specific details
concerning the nature and use of indoo'r radon data sets"other than the State/EPA Residential
Radon Survey are discussed in the individual  State chapters.

RADON INDEX AND CONFIDENCE INDEX

    Many of the geologic methods used to evaluate an area for radon potential require
subjective opinions based on the professional judgment and experience of the individual
geologist.  The evaluations are nevertheless based on  established scientific  principles that are
universally applicable to any geographic area or geologic setting. This section describes the
methods  and conceptual framework used by the U.S.  Geological Survey to evaluate areas for
radon potential based on the five factors discussed in  the previous sections. The scheme is
divided into two basic parts, a Radon Index (RI), used to rank the general  radon potential of
the area,  and the Confidence Index (CI), used to express the level of confidence in the
prediction based on the quantity and quality of the data used to  make the determination.   This
scheme works best if the areas to be evaluated are delineated  by geologically-based
boundaries (geologic provinces) rather than political ones (state/county boundaries) in which
the geology may vary across the area.
    Radon Index.  Table 1 presents the Radon Index (RI) matrix. The five factors—indoor
radon data, geology, aerial radioactivity, soil parameters, and house foundation type—were
quantitatively  ranked (using a point value of 1, 2, or 3) for their respective contribution to
radon potential in a given area.  At least some data for the 5 factors are consistently available
for every geologic province.  Because  each of these main factors encompass a wide  variety  of
complex  and variable components, the geologists performing the evaluation relied heavily on
their professional judgment and experience in assigning point values to each category and in
determining the  overall radon potential ranking. Background  information on these factors is
discussed in more detail in the preceding sections of this introduction.
    Indoor radon was evaluated using  unweighted arithmetic means of the  indoor radon  data
for each  geologic area to be assessed.  Other expressions of indoor  radon levels in an area
also could have  been  used, such as weighted averages or annual averages,  but these types of
data were not consistently available for the entire United States  at the time of this writing, or
the schemes were not considered sufficient to provide a means of consistent comparison
across all areas.  For this report, charcoal-canister screening measurement data from the
State/EPA Residential Radon Surveys  and other carefully  selected sources  were used, as
described in the preceding section.  To maintain consistency, other  indoor  radon data sets
(vendor,  state, or other  data) were not considered in scoring the indoor radon factor of the
Radon Index if they were not randomly sampled or could not be statistically combined with
the primary indoor radon data sets. However, these additional radon data  sets can provide a
means to further refine correlations between geologic factors and radon potential, so they are


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TABLE 1. RADON INDEX MATRIX, "ppm eU" indicates parts per million of equivalent
uranium, as indicated by NURE aerial radiometric data.  See text discussion for details.


FACTOR
INDOOR RADON (average)

AERIAL RAD1OACT1 Vi'iY
GEOLOGY*
SOIL PERMEABILITY
ARCHITECTURE TYPE


1
<2pCi/L

..5 ppm eU
negative
low
mostly slab

POINT VALUE
2
— ••'•
2 - 4 pCi/L

.5 - 2..J ppm eu
variable
moderate
mixed


3
>4pCi/L

z..j ppm cu
positive
high
mostly basement
*GEOLOGIC FIELD EVIDENCE (GFE) POINTS: GFE points are assigned in addition to points
   for the "Geology" factor for specific, relevant geologic field studies. See text for details.

   Geologic evidence supporting:   HIGH radon        +2 points
                              MODERATE       +1 point
                              LOW              -2 points
                  No relevant geologic field studies     0 points
 SCORING:
             Radon potential category
                                   Probable average screening
                      Point ranee     indnnr radon for area
             LOW
             MODERATE/VARIABLE
             HIGH
                      3-8 points
                     9-11 points
                    12-17 points
           <2pCi/L
           2-4pCi/L
           >4pCi/L
                      POSSIBLE RANGE OF POINTS = 3 to 17
 TABLE 2.  CONFIDENCE INDEX MATRIX

FACTOR
INDOOR RADON DATA

AERIAL RADlOACriVJLi Y
GEOLOGIC DATA
SOIL PERMEABILITY

1


questionable/no data
questionable
questionable/no data
POINT VALUE
2
fair coverage/quality

glacial cover
variable
variable
	 ^
3
good coverage/quality


proven geol. model
reliable, abundant
 SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
 4-6  points
 7-9  points
10 -12 points
                       POSSIBLE RANGE OF POINTS = 4 to 12
                                      II-12     Reprinted ftom USGS Open-File Report 93-292

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included as supplementary information and are discussed in the individual State chapters. If
the average screening indoor radon level for an area was less than 2 pCi/L, the indoor radon
factor was assigned 1 point, if it was between 2 and 4 pCi/L, it was scored 2 points, and if
the average screening indoor radon level for an area was greater than 4 pCi/L,.the indoor
radon factor was assigned 3 RI points.
    Aerial radioactivity data used in this report are from the equivalent uranium map of the
conterminous UnitecLStates compiled from NURE aerial gamma-ray surveys (Duval and
others, 1989).  These data indicate the gamma radioactivity from approximately the upper 30
cm of rock and soil, expressed in units of ppm equivalent uranium.  An approximate average
value of eU was  determined visually for each area and point values assigned based on
whether the overall eU for the area falls below 1.5  ppm (1 point), between 1.5 and 2.5 ppm
(2 points), or greater than 2.5 ppm  (3 points).
    The geology  factor is complex and actually incorporates many geologic characteristics.  In
the matrix, "positive" and "negative" refer to the presence or absence and distribution of rock
types known to have high uranium contents and to  generate elevated radon in soils or indoors.
Examples of "positive" rock types include granites, black shales, phosphatic rocks, and other
rock types described in the preceding "geologic data" section.  Examples of "negative" rock
types include marine quartz sands and some clays.  The term "variable" indicates that the
geology within the region is variable or that the rock types in  the area are known or suspected
to generate elevated radon in. some areas but not in others  due to compositional differences,
climatic effects, localizeddistribution of uranium, or other factors.  Geologic information
indicates not only how much uranium is present in the rocks and soils but also gives clues for
predicting general radon emanation and mobility characteristics through additional factors
such as structure (notably the presence of faults or  shears) and geochemical characteristics
(for example, a phosphate-rich sandstone will likely contain more uranium than a sandstone
containing little or no  phosphate because the phosphate forms chemical complexes with
uranium). "Negative", "variable", and "positive" geology were assigned 1, 2, and 3 points,
respectively.
    In cases where additional reinforcing or contradictory geologic evidence is available,
Geologic Field Evidence (GFE) points were added  to or subtracted from an area's score
(Table 1). Relevant geologic field studies are important to enhancing our understanding of
how geologic processes affect radon distribution.  In some cases, geologic models and
supporting field data reinforced an already strong (high or low) score; in  others, they provided
important contradictory data.  GFE points were applied for geologically-sound evidence that
supports the prediction (but which may contradict one or more factors) on the basis of known
geologic field studies  in the area or in areas with geologic and climatic settings similar
enough that they could be applied with full confidence.  For example, areas of the Dakotas,
Minnesota, and Iowa that are covered with Wisconsin-age glacial deposits exhibit a low aerial
radiometric signature and score only one RI point in that category.  However, data from
geologic  field studies  in North Dakota and Minnesota (Schumann and others, 1991) suggest
that eU is a poor predictor of geologic radon potential in this area because radionuclides have

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 been leached from the upper soil layers but are present and possibly even concentrated in
 deeper soil horizons, generating significant soil-gas radon.  This positive supporting field
 evidence adds two GFE points to the score, which helps to counteract the invalid conclusion
 suggested by the radiometric data.  No GFE points are awarded if there are no documented
 field studies for the area.
     "Soil permeability" refers to several soil characteristics that influence radon concentration
 and mobility, including soil type, grain size, structure, soil moisture, drainage, slope, and
 permeability.  In the matrix, "low"  refers to permeabilities less than about 0.6 in/hr; "high"
 corresponds to  greater than about 6.0 in/hr, in U.S. Soil  Conservation Service (SCS) standard
 soil percolation tests.  The SCS data are for water permeability, which generally correlates
 well with the gas permeability of the soil  except when the soil moisture content is  very  high.
 Areas with consistently high water  tables were thus considered to have low gas permeability.
 "Low,  "moderate", and "high" permeability were assigned 1,  2, and 3 points, respectively.
     Architecture type refers to whether homes in the  area have mostly basements (3 points),
 mostly slab-on-grade construction (1  point), or a mixture of the'two. Split-level and crawl
 space homes fall into the "mixed" category (2 points).  Architecture information is necessary
 to properly interpret the  indoor radon data and produce geologic radon potential categories
 that are consistent with screening indoor radon data.
      The overall RI  for an area is calculated by adding the individual RI scores for the 5
 factors, plus or minus GFE points,  if any.  The total RI  for an area falls in  one of  three
 categories—low, moderate or variable, or high.  The  point ranges for the three categories were
 determined by  examining the possible combinations of points for the 5 factors and setting
 rules such that a majority (3 of 5 factors) would determine the final score for the low and
 high categories, with allowances for possible deviation from  an ideal score  by the  other two
 factors.  The moderate/variable category lies between these two ranges.  A  total deviation of 3
 points from the "ideal" score was considered reasonable to allow for natural variability of
 factors—if two of the five factors are allowed to vary from the "ideal" for  a category, they
 can differ by a minimum of 2 (1 point different each) and a maximum of 4 points (2 points
 different each). With "ideal" scores of 5,  10, and 15 points  describing low, moderate, and
 high geologic radon potential, respectively, an ideal low score of 5 points plus  3 points for
 possible variability allows a maximum of 8 points in the low category.  Similarly, an ideal
, high score of 15  points minus 3 points gives  a minimum of 12 points for the high category.
 Note, however, that if both other factors differ by  two points from the "ideal",  indicating
 considerable variability in the system, the total point score would lie in the adjacent (i.e.,
 moderate/variable) category.
      Confidence Index.  Except for architecture type, the same factors were used to establish a
 Confidence Index (CI) for the radon potential prediction for each area (Table 2).   Architecture
 type was not included in the confidence index because house construction  data are readily  and
 reliably available through surveys  taken by agencies and industry groups including the
 National Association of Home Builders, U.S. Department of Housing and Urban
 Development, and the Federal Housing Administration; thus it was not considered necessary

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to question the quality or validity of these data.  The other factors were scored on the basis of
the quality and quantity of the data used to complete the RI  matrix.
    Indoor radon data were evaluated based on the distribution and number of data points and
on whether the data were collected by random sampling (State/EPA Residential Radon Survey
or other state survey data) or volunteered vendor data (likely to be nonrandom and biased
toward  population centers and/or high indoor radon levels).  The categories listed in the CI
matrix for indoor radon data ("sparse or no data'.', "fair coverage or quality", and  "good
coverage/quality") indicate the sampling density and statistical robustness of an indoor radon
data set.  Data from the State/EPA Residential Radon Survey and statistically  valid state
surveys were typically assigned 3 Confidence Index points unless the data  were poorly
distributed or absent in the area evaluated.
    Aerial radioactivity data are  available for all but a few areas of the continental United
States and for part  of Alaska.  An evaluation of the quality of the radioactivity data was based
on whether there appeared to be  a good correlation between the radioactivity and the actual
amount of uranium or radium available to generate mobile radon  in the rocks  and soils of the
area evaluated.  In  general, the greatest problems with correlations among eU, geology, and
soil-gas or indoor radon levels were associated with glacial deposits (see the discussion in a
previous section) and typically were assigned a 2-point Confidence Index score.  Correlations
among  eU, geology, and  radon were generally sound in unglaciated areas and  were usually
assigned 3 CI points.  Again, however, radioactivity data in  some unglaciated  areas may have
been  assigned fewer than 3 points, and in glaciated areas may be assigned  only one point, if
the data were considered  questionable or if coverage was poor.
    To  assign Confidence Index  scores for the geologic data factor, rock types and geologic
settings for which a physical-chemical, process-based understanding of radon generation and
mobility exists were regarded as having "proven geologic models" (3 points);  a high
confidence could be held for predictions in such areas.  Rocks for which the processes are '
less well known or for which data are contradictory were regarded as "variable" (2 points),
and those about which little  is known or for which no apparent correlations have been found
were deemed "questionable" (1 point).
    The soil permeability factor  was also scored based on quality and amount of data.  The
three categories for soil permeability in the Confidence Index are similar in concept, and
scored  similarly, to those for the geologic data factor. Soil  permeability can be roughly
estimated from grain size and drainage class if data from standard, accepted soil  percolation
tests  are unavailable; however, the reliability of the data would be lower than if percolation
test figures or other measured permeability data are available, because an estimate of this type
does not encompass all the factors that affect soil  permeability and thus may  be inaccurate in
some instances,  Most published soil permeability data are for water; although this is
generally closely related  to the air permeability of the soil, there are some instances when it
may  provide  an incorrect estimate.  Examples of areas in which water permeability data may
not accurately reflect air permeability include areas with consistently high levels of soil
moisture, or clay-rich soils,  which would have a low water  permeability but may have a

                                            11-15     Reprinted from USGS Open-File Report 93-292

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significantly higher air permeability when dry due to shrinkage cracks in the soil. These
additional factors were applied to the soil permeability factor when assigning the RI score, but
may have less certainty in some cases and thus would be assigned a lower CI score.
    The Radon Index and Confidence Index give a general indication of the relative
contributions of the interrelated geologic factors influencing radon generation and transport in
rocks and soils,  and thus, of the potential for elevated indoor radon levelsto occur in a
particular area.  However, because these reports are somewhat generalized to cover relatively
large areas of States, it is highly  recommended that more detailed studies be performed in
local  areas of interest, using the methods  and general information in these booklets as a guide.
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                                 REFERENCES CITED

Akerblom, G., Anderson, P., and Clavensjo, B., 1984, Soil gas radon--A source for indoor radon
       daughters: Radiation Protection Dosimetry, v. 7, p. 49-54.

Deffeyes, K.S., and MacGregor, I.D., 1980, World uranium resources: Scientific American,
       v. 242, p. 66-76.

Durrance, E.M., 1986, Radioactivity in geology: Principles and applications:  New York, N.Y.,
       Wiley and Sons, 441 p.

Duval, J.S., 1989, Radioactivity and some of its applications in geology: Proceedings of the
       symposium on the application of geophysics to engineering and environmental problems
       (SAGEEP), Golden, Colorado, March 13-16,1989:  Society of Engineering and Mineral
       Exploration Geophysicists, p. 1-61.

Duval, J.S., Cook, E.G., and Adams, J.A.S., 1971, Circle of investigation of an airborne
       gamma-ray spectrometer: Journal of Geophysical Research, v. 76, p. 8466-8470.

Duval, J.S., Jones, W.J., Riggle, F.R., and Pitkin, J.A., 1989, Equivalent uranium map of
       conterminous United States: U.S. Geological Survey Open-File Report 89-478, IQp.

Duval, J.S., Reimer, G.M., Schumann, R.R., Owen, D.E., and Otton, J.K., 1990, Soil-gas
       radon compared to aerial and ground gamma-ray measurements at study sites near Greeley
       and Fort Collins, Colorado: U.S. Geological Survey Open-File Report 90-648,42 p.

Dziuban, J.A., Clifford, M.A., White, S.B., Bergstein, J.W., and Alexander, B.V.,  1990,
       Residential radon survey of twenty-three States, in Proceedings of the 1990 International
       Symposium on Radon and Radon Reduction Technology, Vol. UJ: Preprints: U.S.
       Environmental Protection Agency report EPA/600/9-90/005c, Paper IV-2,17 p.

Gammage, R.B., Wilson, D.L., Saultz, R.J., and Bauer, B.C., 1993,  Subtereanean transport of
       radon and elevated indoor radon in hilly karst terranes: Atmospheric Environment
       (in press).

Gundersen, L.C.S., Reimer, G.M., and Agard, S.S., 1988a, Correlation between geology, radon
       in soil gas, and indoor radon in the Reading Prong, in Marikos, M.A., and Hansman, ,
       R.H., eds., Geologic causes of natural radionuclide anomalies: Missouri Department of
       Natural Resources Special Publication 4, p. 91-102.

Gundersen, L.C.S, Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988b, Map showing radon
       potential of rocks and soils in Montgomery County, Maryland: U.S. Geological Survey
       Miscellaneous Field Studies Map MF-2043, scale 1:62,500.

Gundersen, Linda C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
       Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water:
       U.S. Geol. Survey Bulletin no. 1971, p. 39-50.
                                         JI-17     Reprinted from USGS Open-File Report 93-292

-------
Henry, Mitchell E., Kaeding, Margret R, and Monteverde, Donald, 1991, Radon in soil gas and
       gamma-ray activity of rocks and soils at the Mulligan Quarry, Clinton, New Jersey, in
       Gundersen, Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks,
       soils, and water:  U.S. Geol. Survey Bulletin *" 1971, p. 65-75.

Klusman, R. W., and Jaacks, J. A., 1987, Environmental influences upon mercury, radon, and
       helium concentrations in soil gases at a site near Denver, Colorado: Journal of
       Geochemical-Exploration, v. 27, p. 259.-280.       ,.  .

Kovach, E.M., 1945, Meteorological influences upon the radon content of soil gas: Transactions,
       American Geophysical Union, v. 26, p. 241-248.

Kunz, C., Laymon, C.A., and Parker, C, 1989, Gravelly soils and indoor radon, in Osborne,
       M.C., and Harrison, J., eds., Proceedings of the  1988 EPA Symposium on Radon and
       Radon Reduction Technology, Volume 1: U.S. Environmental Protection Agency Report
       EPA/600/9-89/006A, p. 5-75-5-86.

Muessig, K., and Bell, C., 1988, Use of airborne radiometric data to direct testing for elevated
       indoor radon: Northeastern Environmental Science, v. 7, no. 1, p. 45-51.

Ronca-Battista, M., Moon, M., Bergsten, J., White, S.B., Holt, N., and Alexander, B., 1988,
       Radon-222 concentrations in the United States-Results of sample surveys in five states:
       Radiation Protection Dosimetry, v. 24, p. 307-312.

Rose, A.W., Washington, J.W., and Greeman, D.J., 1988, Variability of radon with depth and
       season in a central Pennsylvania soil developed on limestone:  Northeastern Environmental
       Science, v. 7, p. 35-39.

Schery, S.D., Gaeddert, D.H., and Wilkening, M.H.,  1984, Factors affecting exhalation of radon
       from a gravelly sandy loam: Journal of Geophysical Research, v. 89, p. 7299-7309.

Schumann, R.R., and Owen, D.E., 1988, Relationships between geology, equivalent uranium
       concentration, and radon in soil gas, Fairfax County, Virginia: U.S. Geological Survey
       Open-File Report 88-18,28 p.

Schumann, R.R., and Gundersen, L.C.S., 1991, Regional differences in radon emanation
       coefficients in soils: Geological Society of America Abstracts With Programs, v. 23,
       no. 1, p. 125.

Schumann, R.R., Peake, R.T., Schmidt, K.M., and Owen, D.E., 1991, Correlations of soil-gas
       and indoor radon with geology in glacially derived soils of the northern Great Plains, in
       Proceedings of the 1990 International Symposium on Radon and Radon Reduction
       Technology, Volume 2, Symposium Oral Papers: U.S. Environmental Protection Agency
       report EPA/600/9-9l/026b, p. 6-23-6-36.
                                         JJ-18     Reprinted from USGS Open-File Report 93-292

-------
Schumann, R.R., Owen, D.E., and Asher-Bolinder, S., 1992, Effects of weather and soil
       characteristics on temporal variations in soil-gas radon concentrations, in Gates, A.E., and
       Gundersen, L.C.S., eds., Geologic controls on radon: Geological Society of America
       Special Paper 271, p. 65-72.

Sextro, R.G., Moed, B.A., Nazaroff, W.W., Revzan, K.L., and Nero, A.V., 1987,
       Investigations of soil as a source of indoor radon, in Hopke, P.K., ed., Radon and its
       decay products: American Chemical Society Symposium Series 331, p. 10-29.

Sterling, R., Meixel, G., Shen, L., Labs, K., and Bligh, T., 1985, Assessment of the energy
       savings potential of building foundations research: Oak Ridge, Term., U.S. Department of
       Energy Report ORNL/SUB/84-0024/1.

Smith, R.C., H, Reilly, M.A., Rose, A.W., Barnes, J.H., and Berkheiser, S.W.,  Jr., 1987,
       Radon: a profound case: Pennsylvania Geology, v. 18, p. 1-7.

Tanner, A.B., 1964, Radon migration in the ground: a review, in Adams, J.A.S., and Lowder,
       W.M., eds., The natural radiation environment: Chicago, HI., University of Chicago
       Press, p.  161-190.

Tanner, A.B., 1980, Radon migration in the ground: a supplementary review, in Gesell, T.F.,
       and Lowder, W.M. (eds), Natural radiation environment m, Symposium proceedings,
       Houston, Texas, v. 1, p. 5-56.

U.S. Department of Agriculture, 1987, Principal kinds of soils:  Orders, suborders, and great
       groups: U.S. Geological Survey, National Atlas of the United States of America, sheet
       38077-BE-NA-07M-00, scale 1:7,500,000.

U.S. Department of Energy, 1976, National Uranium Resource Evaluation preliminary report,
       prepared by the U.S. Energy Research and Development Administration, Grand Junction,
       Colo.: GJO-11(76).

Wanty, Richard B., and Schoen, Robert, 1991, A review of the chemical processes affecting the
       mobility of radionuclides in natural waters, with applications, in Gundersen, Linda C.S.,
       and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water: U.S.
       Geological Survey Bulletin no. 1971, p. 183-194.

Washington, J.W., and Rose, A.W., 1990, Regional and temporal relations of radon in soil gas to
       soil temperature and moisture: Geophysical Research Letters, v. 17, p. 829-832.

White, S.B., Bergsten, J.W., Alexander, B.V., and Ronca-Battista, M., 1989, Multi-State
       surveys of indoor 222Rn: Health Physics, v. 57, p. 891-896.
                                          JI-19     Reprinted fiom USGS Open-File Report 93-292

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                                           .  APPENDIX  A
                                      GEOLOGIC TIME SCALE
Subdivisions (and their symbols)
Eon or
Eonothem
Phanerezoic2

Proteroioic
/Dl
(CJ

Archean
(A)
Era or
Erathem
Cenozoic
(CD
Mesozoic3
(Mz)
Paleozoic
(Pi)
L»lt
M«3s;t

Ut«
Miodi*
t»rtv
Period, System,
Subperiod, Subsystem
Quaternary
IQ)
Neogene 2
Subperiod or '
T.rrlary Subsystem (N)
m Paleogen*
11 Suboeriodor
Subsystem (Pi)
Cretaceous
(K)
Jurassic
(J)
Triassic
(Ti)
Permian
(P)
Pennsylvanian
Carboniferous 'P'
'C) Mississippian
(M)
Devonian
(D)

Silurian
(S)
Ordovician
(Q)

Cambrian
(C)
Epoch or Series
Age estimates
of boundaries
in mega-annum
(Ma)1
Holocene 001Q
Pleistocene
.Pliocene , „ „„*...
Miocene
Oligocene
Eocene
Paleocene
Late
Early
Late
Middle
Upper
Lower
Upper
Middle
Early | Lower
Late
Middle
Early
Late
Early
Late
Middle
Early
Late
Early
Late
Middle
Early
Late
Middle
Early
Late
Middle
Early
Late
Middle
Early
Upper
Middle
Lower
Upper
Lower
Upper
Middle
Lower
Upper
Lower
Uooer
Middle
Lower
Upper
Middle
Lower
Upper
Middle
Lower
Upper
Middle
Lower
None defined
None defined
None defined
None defined
None defined
None defined
pr*-Arc>it>n IpA) '
•M /•>f!l
•so >i< na\
- fC\ IKK KK\



























.570 3


	 2500
	 3000

	 3800 ?

           reflect uncertainties of Isotopic and btostratigraphic age assignments. Age boundaries not closely bracketed by existing
data »hown by •> Decay constants and feotopic ratios employed are cited in Steiger and Jfiger (1977). Designation m.y. used for an
Interval of Um«.
   'Modifier* (tower, middle, upper or early, middle, late) when used with these hems are informal divisions of the larger unit; the
first toner ol the modifier Is lowercase.
   'Rocks older than 570 Ma aJso called Precambrian (pC). a lime term without specific rank.
   'informal time term without specific rank.
                                       USGS Open-File Report 93-292

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                                    APPENDIX  B
                               GLOSSARY OF TERMS
Jmcs of measure
pCi/L (picocuries per liter)- a unit of measure of radioactivity used to describe radon
concentrations in a volume of air. One picocurie (10~12 curies) is equal to about 2.2 disintegrations
of radon atoms per minute. A liter is about 1.06 quarts. The average concentration of radon in
U.S. homes measured to date is between 1 and 2 pCi/L.

Bq/m3 (Becquerels per cubic meter)- a metric unit of radioactivity used to describe radon
concentrations in a volume of air. One becquerel is equal to one radioactive disintegration per
second. One pCi/L is equal to 37 Bq/m3.

ppm (parts per million)- a unit pf measure of concentration by weight of an element in a
substance, in this case, soil or rock.  One ppm of uranium contained in a ton of rock corresponds
to about 0.03 ounces of uranium. The average concentration of uranium in soils in the United
States is between 1 and 2 ppm.

in/hr (inches per hour)- a unit of measure used by soil scientists and engineers to describe the
permeability of a soil to water flowing through it It is measured by digging a hole 1  foot (12
inches) square and one foot deep, fining it with water, and measuring the time it takes for the water
to drain from the hole. The drop in height of the water level in the hole, measured in inches, is
then divided by the time (in hours) to determine the permeability. Soils range in permeability from
less than 0.06 in/hr to greater than 20 in/hr, but most soils in the United States have permeabilities
between these two extremes.
Geologic terms and terms related to the study of radon

aerial radiometric, aeroradiometric survey A survey of radioactivity, usually gamma rays,
taken by an aircraft carrying a gamma-ray spectrometer pointed at the ground surface.

alluvial fan A low, widespread mass of loose rock and soil material, shaped like an open fan
and deposited by a stream at the point where it flows from a narrow mountain valley out onto a
plain or broader valley. May also form at the junction with larger streams or when the gradient of
the stream abruptly decreases.

alluvium, alluvial General terms referring to unconsolidated detrital material deposited by a
stream or other body of running water.

alpha-track detector  A passive radon measurement device consisting of a plastic film that is
sensitive to alpha particles.  The film is etched with acid in a laboratory after it is exposed. The
etching reveals scratches, or "tracks", left by the alpha particles resulting from radon decay, which
can then be counted to calculate the radon concentration. Useful for long-term (1-12 months)
radontests.

amphibolite A mafic metamorphic rock consisting mainly of pyroxenes and(or) amphibole and
plagioclase.
                                           11-21      Reprinted from USGS Open-File Report 93-292

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argillite, argillaceous Terms referring to a rock derived from clay or shale, or any sedimentary
rock containing an appreciable amount of clay-size material, i.e., argillaceous sandstone.

arid Term describing a climate characterized by dryness, or an evaporation rate that exceeds the
amount of precipitation.

basalt A general term for a dark-colored mafic igneous rocks that may be of extrusive origin,
such as volcanic basalt flows, or intrusive origin, such as basalt dikes.

batholith  A mass of plutonic igneous rock that has more than 40 square miles of surface
exposure and no known bottom.

carbonate  A sedimentary rock consisting of the carbonate (COs) compounds of calcium,
magnesium, or iron, e.g. limestone and dolomite.

carbonaceous Said of a rock or sediment that is rich in carbon, is coaly, or contains organic
matter.

charcoal canister A passive radon measurement device consisting of a small container of
granulated activated charcoal that is designed to adsorb radon.  Useful for short duration (2-7 days)
measurements only. May be referred to as a "screening" test

chert A hard, extremely dense sedimentary rock consisting dominantly of interlocking crystals of
quartz. Crystals are not visible to the naked eye, giving the rock a milky, dull luster.  It may be
white or gray but is commonly colored red, black, yellow,  blue, pink, brown, or green.

clastic pertaining to a rock or sediment composed of fragments that are derived from preexisting
rocks or minerals. The most common clastic sedimentary rocks are sandstone and shale.

clay A rock containing clay mineral fragments or material of any composition having a diameter
less than 1/256 mm.

clay mineral One of a complex and loosely defined group of finely crystalline minerals made up
of water, silicate and aluminum (and a wide variety of other elements). They are formed chiefly by
alteration or weathering of primary silicate minerals. Certain clay minerals are noted for their small
size and ability to absorb substantial amounts of water, causing them to swell. The change in size
that occurs as these clays change between dry and wet is referred to as their "shrink-swell"
potential.

concretion A hard, compact mass of mineral matter, normally subspherical but commonly
irregular in shape; formed by precipitation from a water solution about a nucleus or center, such as
a leaf, shell, bone, or fossil, within a sedimentary or fractured rock.

conglomerate A coarse-grained, clastic sedimentary rock composed of rock and mineral
fragments larger than 2 mm, set in a finer-grained matrix of clastic material.

cuesta A hill or ridge with a gentle slope on one side and a steep slope on the other. The
formation of a cuesta is controlled by the different weathering properties and the structural dip of
the rocks forming the hill or ridge.

daughter product A nuclide formed by the disintegration of a radioactive precursor or "parent"
atom.
                                          11-22     Reprinted from USGS Open-File Report 93-292

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delta, deltaic  Referring to a low, flat, alluvial tract of land having a triangular or fan shape,
located at or near the mouth of a river. It results from the accumulation of sediment deposited by a
river at the point at which the river loses its ability to transport the sediment, commonly where a
river meets a larger body of water such as a lake or ocean.

dike A tabular igneous intrusion of rock, younger than the surrounding rock, that commonly cuts
across the bedding or foliation of the rock it intrudes.

diorite  A plutonic igneous rock that is medium in color and contains visible dark minerals that
make up less than 50% of the rock.  It also contains abundant sodium plagioclase and minor
quartz.

dolomite A carbonate sedimentary rock of which more than 50% consists of the mineral dolomite
(CaMg(CO3)2), and is commonly white, gray, brown, yellow, or pinkish in color.

drainage The manner in which the waters of an area pass, flow off of, or flow into the soil.
Also refers to the water features of an area, such  as lakes and rivers, that drain it.

eolian Pertaining to sediments deposited by the wind.

esker A long, narrow, steep-sided ridge composed of irregular beds of sand and gravel deposited
by streams beneath a glacier and left behind when the ice melted.

evapotranspiration Loss of water from a land  area by evaporation from the soil and
transpiration from plants.

extrusive  Said of igneous rocks that have been  erupted onto the surface of the Earth.

fault A fracture or zone of fractures in rock or sediment along which there has been movement.

fluvial, fluvial deposit  Pertaining to sediment that has been deposited by a river or stream.

foliation A linear feature in a rock defined by both mineralogic and structural characteristics. It
may be formed during deformation or metamorphism.

formation  A mappable body of rock having similar characteristics.

glacial deposit  Any sediment transported and deposited by a glacier or processes associated
with glaciers,  such as glaciofluvial sediments deposited by streams flowing from melting glaciers.

gneiss A rock formed by metamorphism in which bands and lenses of minerals of similar
composition alternate with bands and lenses of different composition, giving the rock a striped or
 "foliated" appearance.

granite Broadly applied, any coarsely crystalline, quartz- and feldspar-bearing igneous plutonic
rock. Technically, granites have between 10 and 50% quartz, and alkali feldspar comprises at least
 65% of the total feldspar.

 gravel An unconsolidated, natural accumulation of rock fragments consisting predominantly of
particles greater than 2 mm in size.

 heavy minerals Mineral grains in sediment or  sedimentary rock having higher than average
 specific gravity. May form layers and lenses because of wind or water sorting by weight and  size
                                           n-23     Reprinted from USGS Open-File Report 93-292

-------
 and may be referred to as a "placer deposit." Some heavy minerals are magnetite, garnet, zircon,
 monazite, and xenotime.
 igneous Said of a rock or mineral that solidified from molten or partly molten rock material. It is
 one of the three main classes into which rocks are divided, the others being sedimentary and
 metamorphic.
 intermontane A term that refers to an area between two mountains or mountain ranges.
 intrusion, intrusive The processes of emplacement or injection of molten rock into pre-existing
 rock. Also refers to the rock formed by intrusive processes, such as an "intrusive igneous rock".
 kame A low mound, knob, hummock, or short irregular ridge formed by a glacial stream at the
 margin of a melting glacier; composed of bedded sand and gravel.
 karst terrain A type of topography that is formed on limestone, gypsum and other rocks by
 dissolution of the rock by water,'forming sinkholes and caves.
 lignite A brownish-black coal that is intermediate in coalification between peat and
 subbituminous coal.
 limestone A carbonate sedimentary rock consisting  of more than 50% calcium carbonate,
 primarily in the form of the mineral calcite (CaCOs).
 lithology  The description of rocks in hand specimen and in outcrop on the basis of color,
 composition, and grain size.
 loam A permeable soil composed of a mixture of relatively equal parts clay, silt, and sand, and
 usually containing some organic matter.
 loess  A fine-grained eolian deposit composed of silt-sized particles generally thought to have
 been deposited from windblown dust of Pleistocene age.
 mafic Term describing an igneous rock containing more than 50% dark-colored minerals.
 marine Term describing sediments deposited in the ocean, or precipitated from ocean waters.
 metamorphic Any rock derived from pre-existing rocks by mineralogical, chemical, or structural
 changes in response to changes in temperature, pressure, stress, and the chemical environment.
 PhylKte, schist, amphibolite, and gneiss are metamorphic rocks.
 moraine A mound, ridge, or other distinct accumulation of unsorted, unbedded glacial material,
predominantly till, deposited by the action of glacial ice.
 outcrop That part of a geologic formation or structure that appears at the surface of the Earth, as
in "rock outcrop".
 percolation test A term used in engineering for a test to determine the water permeability of a
 soft. A hole is dug and filled with water and the rate of water level decline is measured.
 permeability The capacity of a rock, sediment, or soil to transmit liquid or gas.
phosphate, phpsphatic, phosphorite Any rock or sediment containing a significant amount
of phosphate minerals, i.e., minerals containing PO4.

                                          n-24      Reprinted from USGS Open-File Report 93-292

-------
physiographic province A region in which all parts are similar in geologic structure and
climate, which has had a uniform geomorphic history, and whose topography or landforms differ
significantly from adjacent regions.

placer deposit See heavy minerals

residual Formed by weathering of a material in place.

residuum Deposit of residual material.

rhyolite An extrusive igneous rock of volcanic origin, compositionally equivalent to granite.

sandstone A clastic sedimentary rock composed of sand-sized rock and mineral material that is
more or less firmly cemented. Sand particles range from 1/16 to 2 mm in size.

schist  A strongly foliated crystalline rock, formed by metamorphism, that can be readily split into
thin flakes or slabs.  Contains mica; minerals are typically aligned.

screening level  Result of an indoor radon test taken with a charcoal canister or similar device,
for a short period of time, usually less than seven days. May indicate the potential for an indoor
radon problem but does not indicate annual exposure  to radon.

sediment Deposits of rock and mineral particles or fragments originating from material that is
transported by air, water or ice, or that accumulate by  natural chemical precipitation or secretion of
organisms.

semiaricl Refers to a climate that has slightly more precipitation than an arid climate.

shale  A fine-grained sedimentary rock formed from  solidification Oithificatipn) of clay or mud.

shear zone Refers to a roughly linear zone of rock that has been faulted by ductile or non-ductile
processes in which the rock is sheared and both sides are displaced relative to one  another.

shrink-swell clay See clay mineral.

siltstone A fine-grained clastic sedimentary rock composed of  silt-sized rock and mineral
material and more or less firmly cemented.  Silt particles range from 1/16 to  1/256 mm in size.

sinkhole A roughly circular depression in a karst area measuring meters to tens of meters in
diameter. It is funnel shaped and is formed by collapse of the surface material into an underlying
void created by the dissolution of carbonate rock.

slope An inclined part of the earth's surface.

 solution cavity A hole, channel or cave-like cavity formed by dissolution of rock.

 stratigraphy The study of rock strata; also refers to the succession of rocks of a particular area.

 surficial materials Unconsolidated glacial, wind-, or waterborne deposits occurring on the
 earth's surface.                                                .

 tablelands General term for a broad, elevated region with a nearly level surface of considerable
 extent.
                                            E-25      Reprinted from USGS Open-File Report 93-292

-------
terrace gravel  Gravel-sized material that caps ridges and terraces, left behind by a stream as it
cuts down to a lower level.

terrain A tract or region of the Earth's surface considered as a physical feature or an ecological
environment.

till Unsorted, generally unconsolidated and unbedded rock and mineral material deposited directly
adjacent to and underneath a glacier, without reworking by meltwater.  Size of grains varies greatly
from clay to boulders.

uraniferous  Containing uranium, usually more than 2 ppm.

vendor data  Used in this report to refer to indoor radon data collected and measured by
commercial vendors of radon measurement devices and/or services.

volcanic Pertaining to the activities, structures, and extrusive rock types of a volcano.

water table The surface forming the boundary between the zone of saturation and the zone of
aeration; the top surface of a body of unconfined groundwater in rock or soil.

weathering The destructive process by which earth  and rock materials, on exposure to
atmospheric elements, are changed in color, texture, composition, firmness, or form with little or
no transport of the material.
                                           H-26     Reprinted from USGS Open-File Report 93-292

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                                          APPENDIX C
                                  EPA REGIONAL  OFFICES
EPA  Regional  Offices
                                                    State
                             EPA  Region
EPA Region 1
JFK Federal Building
Boston, MA 02203
(617) 565-4502

EPA Region 2
(2AIR:RAD)
26 Federal Plaza
New York, NY 10278
(212) 264-4110

Region 3 (3AH14)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-8326

EPA Region 4
345 Courtland Street, N.E.
Atlanta, GA 30365
(404) 347-3907

EPA Region 5 (5AR26)
77 West Jackson Blvd.
Chicago,  IL 60604-3507
(312)  886-6175

EPA Region 6 (6T-AS)
1445 Ross Avenue
Dallas, TX 75202-2733
(214)  655-7224

EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913)  551-7604

EPA Region 8
 (8HWM-RP)
999 18th Street
One Denver Place, Suite 1300
Denver, CO 80202-2413
(303) 293-1713

EPA Region 9 (A-3)
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1048

EPA Region 10
 1200 Sixth Avenue
 Seattle, WA 98101
 (202) 442-7660
Alabama	:	4
Alaska	-	10
Arizona	9
Arkansas	6
California..	9
Colorado	8
Connecticut	1
Delaware	3
District of Columbia	3
Florida	4
Georgia	,...4
Hawaii	.'	9
Idaho	10
Illinois	5
Indiana	5
Iowa	7
Kansas	:	7
Kentucky	4
Louisiana	6
Maine	1
Maryland	3
Massachusetts	1
Michigan	5
Minnesota	5
Mississippi	4
Missouri	7
Montana	8
Nebraska	7
Nevada	9
New Hampshire	1
New  Jersey	2
New Mexico	6
New York	2
North Carolina	4
North Dakota	8
Ohio	5
Oklahoma	6
Oregon	10
Pennsylvania	3
Rhode Island	1
South Carolina	4
South Dakota	8
Tennessee	4
Texas	6
Utah	8
Vermont	1
 Virginia	3
Washington	10
 West Virginia	3
 Wisconsin	5
 Wyoming	8
                                                 H-27       Reprinted from USGS Open-File Report 93-292

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                                 STATE RADON  CONTACTS
                                             May, 1993
Alabama       James McNees
               Division of Radial" in Control
               Alabama Department of Public Health
               State Office Building
               Montgomery, AL 36130
               (205) 242-5315
               ' 1-800-582-1866 in state
               Charles Tedford
               Department of Health and Social
                 Services
               P.O. Box 110613
               Juneau,AK 99811-0613
               (907)465-3019
               1-800-478-4845 in state

               John Stewart
               Arizona Radiation Regulatory Agency
               4814 South 40th St.
               Phoenix, AZ 85040
               (602) 255-4845
Arkansas       LeeGershner
               Division of Radiation Control
               Department of Health
               4815 Markham Street, Slot 30
               Little Rock, AR 72205-3867
               (501) 661-2301
California       J. David Quinton
               Department of Health Services
               714 P Street, Room 600
               Sacramento, CA 94234-7320
               (916) 324-2208
               1-800-745-7236 in state
Colorado       Linda Martin
               Department of Health
               4210 East llth Avenue
               Denver, CO 80220
               (303) 692-3057
               1-800-846-3986 in state
 Connecticut  Alan J. Siniscalchi
             Radon! ogram
             Connecticut Department of Health
              Services
             150 Washington Street
             Hartford, CT 06106-4474
            "(203) 566-3122

   Delaware  Marai G. Rejai
             Office of Radiation Control
             Division of Public Health
             P.O. Box 637
             Dover, DE 19903
             (302) 736-3028
             1-800-554-4636 In State

    District  Robert Davis
of Columbia  DC Department of Consumer and
              Regulatory Affairs
             614 H Street NW
             Room  1014
             Washington, DC 20001
             (202) 727-71068

    Florida  N. Michael Gilley
             Office of Radiation Control
             Department of Health and
              Rehabilitative Services
             1317 Winewood Boulevard
             Tallahassee, FL 32399-0700
             (904)488-1525
             1-800-543-8279 in state
            Richard Schreiber
            Georgia Department of Human
              Resources
            878 Peachtree St, Room 100
            Atlanta, GA 30309
            (404) 894-6644
            1-800-745-0037 in state
     Hawaii Russell Takata
            Environmental Health Services
              Division
            591 Ala Moana Boulevard
            Honolulu, ffl 96813-2498
            (808) 586-4700
                                               n-28
      Reprinted from USGS Open-File Report 93-292

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Idaho
Illinois
Indiana
Iowa
 Kansas
 Kentucky
PatMcGavarn
Office of Environmental Health
450 West State Street
Boise, ID 83720
(208) 334-6584
1-800-445-8647 in state
Richard Allen
Illinois Department of Nuclear Safety
1301 Outer Park Drive
Springfield, IL 62704
(217) 524-5614
1-800-325-1245 in state
Lorand Magyar
Radiological Health Section
Indiana State Department of Health
1330 West Michigan Street
P.O. Box 1964
Indianapolis, IN 46206
(317) 633-8563
1-800-272-9723 In State

Donald A. Plater
Bureau of Radiological Health
Iowa Department of Public Health
Lucas State Office Building
Des Moines, IA 50319-0075
(515)281-3478
 1-800-383-5992 In State

Harold Spiker
Radiation Control Program
Kansas Department of Health and
   Environment
 109 SW 9th Street
 6th Floor Mills Building
 Topeka, KS 66612
 (913) 296-1561

 JeanaPhelps
 Radiation Control Branch
 Department of Health Services
 Cabinet for Human Resources
 275 East Main Street
 Frankfort, KY 40601
 (502) 564-3700
   Louisiana  Matt Schlenker
              Louisiana Department of
               Environmental Quality
              P.O. Box 82135
              Baton Rouge, LA 70884-2135
              (504) 925-7042
              1-800-256-2494 in state

       Maine  BobStilwell
              Division of Health Engineering
              Department of Human Services
              State House, Station 10
              Augusta, ME 04333
              (207)289-5676
              1-800-232-0842 in state

    Maryland  Leon J. Rachuba
              Radiological Health Program
              Maryland Department of the
               Environment
              2500 Broening Highway
              Baltimore, MD 21224
              (410)631-3301
              1-800-872-3666 In State

Massachusetts  William J. Bell
              Radiation Control Program
              Department of Public Health
              23 Service Center
              Northampton, MA 01060
              (413) 586-7525
              1-800-445-1255 in state

    Michigan  Sue Hendershott
              Division of Radiological Health
              Bureau of Environmental and
                Occupational Health
              3423 North Logan Street
              P.O. Box 30195
              Lansing, MI 48909
              (517) 335-8194

   Minnesota  Laura Oatmann
              Indoor Air Quality Unit
              925 Delaware Street, SE
              P.O. Box 59040
              Minneapolis, MN 55459-0040
              (612)627-5480
              1-800-798-9050 in state
                                                 H-29
                                             Reprinted from USGS Open-File Report 93-292

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Mississipi
Missouri
Montana
               Silas Anderson
               Division of Radiological Health
               Department of Health
               3 150 Lawson Street
               P.O. Box 1700
               Jackson, MS 39215-1700
               (601) 354-6657
               1-800-626-7739 in stale

               Kenneth V-. Miller
               Bureau of Radiological Health
               Missouri Department of Health
               1730 East Elm
               P.O. Box 570
               Jefferson City, MO 65102
               (314)751-6083
               1-800-669-7236 In State

               Adrian C. Howe
               Occupational Health Bureau
               Montana Department of Health and
                 Environmental Sciences
               Cogswell Building A113
               Helena, MT 59620
               (406)444-3671
               Joseph Milone
               Division of Radiological Health
               Nebraska Department of Health
               301 Centennial Mall, South
               P.O. Box 95007
               Lincoln, NE 68509
               (402)471-2168
               1-800-334-9491 In State

               Stan Marshall
               Department of Human Resources
               505 East King Street
               Room 203
               Carson City, NV 89710
               (702) 687-5394
NEW Hampshire David Chase
               Bureau of Radiological Health
               Division of Public Health Services
               Health and Welfare Building
               Six Hazen Drive
               Concord, NH 03301
               (603) 271-4674
               1-800-852-3345 x4674
Nebraska
    New Jersey  Tonalee Carlson Key
               Division of Environmental Quality
               Department of Environmental
                 Protection
               CN415
               Trenton, NJ 08625-0145
               (609) 987-6369
               1-800-648-0394 in state

-  New Mexico  William M. Floyd
               Radiation Licensing and Registration
                 Section
               New Mexico Environmental
                 Improvement Division
               1190 St. Francis Drive
               Santa Fe,NM 87503
               (505) 827-4300

     New York  William J. Condon
               Bureau of Environmental Radiation
                 Protection
               New York State Health Department
               Two University Place
               Albany, NY 12202
               (518)458-6495
               1-800-458-1158 in state

 North Carolina  Dr. Felix Fong
               Radiation Protection Division
               Department of Environmental Health
                 and Natural Resources
               701 Barbour Drive
               Raleigh, NC 27603-2008
               (919) 571-4141
               1-800-662-7301 (recorded info x4196)

  North Dakota  Arlen Jacobson
               North Dakota Department of Health
               1200 Missouri  Avenue, Room 304
               P.O. Box 5520
               Bismarck, ND 58502-5520
               (701)221-5188

         Ohio  Marcie Matthews
               Radiological Health Program
               Department of Health
               1224 Kinnear Road - Suite 120
               Columbus, OH 43212
               (614) 644-2727
               1-800-523-4439 in  state
                                                11-30      Reprinted ftom USGS Open-File Report 93-292

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Oklahoma      Gene Smith
               Radiation Protection Division
               Oklahoma State Department of
                 Health
               P.O. Box 53551
               Oklahoma City, OK 73152
               (405) 271-5221
Oregon         George Toombs
               Department of Human Resources
               Health Division
               1400 SW 5th Avenue
               Portland, OR 97201
               (503) 731^014
Pennsylvania    Michael Pyles
                Pennsylvania Department of
                 Environmental Resources
                Bureau of Radiation Protection
                P.O. Box 2063
                Harrisburg,PA17120
                (717) 783-3594
                1-800-23-RADON In State

Puerto Rico     David Saldana
                Radiological Health Division
                G.P.O. Call Box 70184
                Rio Piedras, Puerto Rico 00936
                (809) 767-3563
 Rhode Island    EdmundArcand
                Division of Occupational Health and
                  Radiation
                Department of Health
                205 Cannon Building
                Davis Street
                Providence, RI02908
                (401) 277-2438
 South Carolina
                Bureau of Radiological Health
                Department of Health and
                  Environmental Control
                2600 Bull Street
                Columbia, SC 29201
                (803)734-4631
                1-800-768-0362
South Dakota MikePochbp
             Division of Environment Regulation
             Department of Water and Natural
               Resources
             Joe Foss Building, Room 217
             523 E. Capitol
             Pierre, SD 57501-3181
             (605) 773-3351

   Tennessee .Susie Shimek
             Division of Air Pollution Control
             Bureau of the Environment
             Department of Environment and
               Conservation
             Customs House, 701 Broadway
             Nashville, TN 37219-5403
             (615) 532-0733
             1-800-232-1139 in state

       Texas Gary Smith
             Bureau of Radiation Control
             Texas Department of Health
             1100 West 49th Street
             Austin, TX 78756-3189
             (512) 834-6688
        Utah  John Hultquist
              Bureau of Radiation Control
              Utah State Department of Health
              288 North, 1460 West
              P.O. Box 16690
              Salt Lake City, UT 84116-0690
              (801) 536-4250

     Vermont  Paul demons
              Occupational and Radiological Health
                Division
              Vermont Department of Health
              10 Baldwin Street
              Montpelier, VT 05602
              (802) 828-2886
              1-800-640-0601 in state

 Virgin Islands  Contact the U.S. Environmental
              Protection Agency, Region II
              in New York
              (212)264-4110
                                                H-31      Reprinted from USGS Open-File Report 93-292

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 Virginia        Shelly Ottenbrite
                Bureau of Radiological Health
                Department of Health
                109 Governor Street
                Richmond, VA 23219
                (804)786-5932
                1-800-468-0138 in state

 Washington     Kate Coleman
                Department of Health
                Office of Radiation Protection
                Airdustrial Building 5, LE-13
                Olympia, WA 98504
                (206)753-4518
                1-800-323-9727 In State

 West Virginia    Beattie L. DeBord
                Industrial Hygiene Division
                West Virginia Department of Health
                151 llth Avenue
                South  Charleston, WV 25303
                (304) 558-3526
                1-800-922-1255 In State

 Wisconsin       Conrad Weiffenbach
                Radiation Protection Section
                Division of Health
                Department of Health and Social
                 Services
                P.O. Box 309
                Madison, WI53701-0309
                (608)267^796
                1-800-798-9050 in state

Wyoming       Janet Hough
                Wyoming Department of Health and
                 Social Services
                Hathway Building, 4th Floor
                Cheyenne, WY 82002-0710
                (307) 777-6015
                1-800-458-5847 in state
                                               11-32      Reprinted from USGS Open-File Report 93-292

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                            STATE GEOLOGICAL SURVEYS
                                            May, 1993
Alabama        Ernest A. Mancini
               Geological Survey of Alabama
               P.O. Box 0
               420 Hackberry Lane
               Tuscaloosa, AL 35486-9780
               (205) 349-2852

Alaska         Thomas E. Smith
               Alaska Division of Geological &
                 Geophysical Surveys
               794 University Ave., Suite 200
               Fairbanks, AK  99709-3645
               (907)479-7147

Arizona        Larry D. Fellows
               Arizona Geological Survey
               845 North Park Ave., Suite 100
               Tucson, AZ 85719
               (602) 882-4795
Arkansas       Norman F. Williams
               Arkansas Geological Commission
               Vardelle Parham Geology Center
               3815 West Roosevelt Rd.
               Little Rock, AR 72204
               (501) 324-9165

California      James F. Davis
               California Division of Mines &
                 Geology
               801 K Street, MS 12-30
               Sacramento, CA 95814-3531
               (916) 445-1923

Colorado       Pat Rogers (Acting)
               Colorado Geological Survey
               1313 Sherman St., Rm 715
               Denver, CO  80203
               (303)866-2611

Connecticut    Richard C. Hyde
               Connecticut Geological & Natural
                 History Survey
               165 Capitol Ave., Rm. 553
               Hartford, CT 06106
               (203) 566-3540

Delaware       Robert R. Jordan
               Delaware Geological Survey
               University of Delaware
                101 Penny Hall
               Newark, DE 19716-7501
                (302) 831-2833
Florida  Walter Schmidt
        Florida Geological Survey
        903 W. Tennessee St.
        Tallahassee, FL 32304-7700
        (904) 488-4191
Georgia  William H. McLemore
        Georgia Geologic Survey
        Rm. 400
        19 Martin Luther King Jr. Dr. SW
        Atlanta, GA 30334
        (404) 656-3214

 Hawaii  Manabu Tagomori
        Dept. of Land and Natural Resources
        Division of Water & Land Mgt
        P.O. Box 373
        Honolulu, ffl 96809
        (808) 548-7539

  Idaho  Earl H. Bennett
        Idaho Geological Survey
        University of Idaho
        Morrill Hall, Rm. 332
        Moscow, ID  83843
        (208) 885-7991

 Illinois  Morris W. Leighton
        Illinois State Geological Survey
        Natural Resources Building
        615 East Peabody Dr.
        Champaign,  IL 61820
        (217) 333-4747

 Indiana Norman C. Hester
        Indiana Geological Survey
        611 North Walnut Grove
        Bloomington, IN 47405
        (812) 855-9350

   Iowa Donald L. Koch
        Iowa Department of Natural Resources
        Geological Survey Bureau
         109 Trowbridge Hall
        Iowa City, IA 52242-1319
         (319) 335-1575

 Kansas Lee C.Gerhard
         Kansas Geological Survey
         1930 Constant Ave., West Campus
         University of Kansas
         Lawrence, KS 66047
         (913) 864-3965
                                               H-33      Reprinted from USGS Open-File Report 93-292

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Kentucky       Donald C. Haney
               Kentucky Geological Survey
               University of Kentucky
               228 Mining & Mineral Resources
                 Building
               Lexington, KY 40506-0107
               (606) 257-5500

Louisiana       William E. Marsalis
               Louisiana Geological Survey
               P.O. Box 2827
               University Station
               Baton Rouge, LA 70821-2827
               (504) 388-5320

Maine          Walter A. Anderson
               Maine Geological Survey
               Department of Conservation
               State House,-Station 22
               Augusta, ME 04333
               (207) 289-2801
Maryland       Emery T. Cleaves
               Maryland Geological Survey
               2300 St. Paul Street
               Baltimore, MD 21218-5210
               (410) 554-5500
Massachusetts   Joseph A. Sinnott
               Massachusetts Office of
                 Environmental Affairs
               100 Cambridge St., Room 2000
               Boston, MA 02202
               (617) 727-9800

Michigan       R. Thomas Segall
               Michigan Geological Survey Division
               Box 30256
               Lansing, MI 48909
               (517) 334-6923

Minnesota      Priscilla C. Grew
               Minnesota Geological Survey
               2642 University Ave.
               St. Paul, MN 55114-1057
               (612)627-4780
Mississippi     S. Cragin Knox
                Mississippi Office of Geology
                P.O. Box 20307
                Jackson, MS 39289-1307
                (601)961-5500
      Missouri  James H. Williams
               Missouri Division of Geology &
                 Land Survey
               111 Fairgrounds Road
               P.O. Box 250
               Rolla, MO 65401
               (314) 368-2109

      Montana  Edward T. Ruppel
               Montana Bureau of Mines & Geology
               Montana College of Mineral Science
                 and Technology, Main Hall
               Butte, MT 59701
               (406) 496-4180

      Nebraska  Perry B. Wigley
               Nebraska Conservation & Survey
                 Division
               113 Nebraska Hall
               University of Nebraska
               Lincoln, NE 68588-0517
               (402) 472-2410

       Nevada  Jonathan G. Price
               Nevada Bureau of Mines & Geology
               Stop 178
               University of Nevada-Reno
               Reno, NV  89557-0088
               (702) 784-6691

New Hampshire  Eugene L.Boudette
               Dept. of Environmental Services
               117 James Hall
               University of New Hampshire
               Durham, NH 03824-3589
               (603) 862-3160

    New Jersey  Haig F. Kasabach
               New Jersey Geological Survey
               P.O. Box 427
               Trenton, NJ 08625
               (609)292-1185

   New Mexico  Charles E. Chapin
               New Mexico Bureau of Mines &
                 Mineral Resources
               Campus Station
               Socorro.NM 87801
               (505) 835-5420

     New York Robert H. Fakundiny
               New York State Geological Survey
               3136 Cultural Education Center
               Empire State Plaza
               Albany, NY 12230
               (518)474-5816
                                                n-34
         Reprinted from USGS Open-File Report 93-292

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 North Carolina  Charles H. Gardner
               North Carolina Geological Survey
               P.O. Box 27687
               Raleigh, NC 27611-7687
               (919) 733-3833

North Dakota    John P. Bluemle
               North Dakota Geological Survey
               600 East Blvd.
               -Bismarck, ND 58505-0840
               (701) 224-4109
               Thomas M. Berg
               Ohio DepL of Natural Resources
               Division of Geological Survey
               4383 Fountain Square Drive
               Columbus, OH 43224-1362
               (614) 265-6576
Oklahoma      Charles J. Mankin
               Oklahoma Geological Survey
               Room N-131, Energy Center
               100E.Boyd
               Norman, OK 73019-0628
               (405)325-3031

Oregon         Donald A. Hull
               DepL of Geology & Mineral Indust.
               Suite 965
               800 NE Oregon St. #28
               Portland, OR 97232-2162
               (503)731-4600

Pennsylvania    Donald M. Hoskins
               Dept. of Environmental Resources
               Bureau of Topographic & Geologic
                 Survey
               P.O. Box 2357
               Harrisburg, PA 17105-2357
               (717) 787-2169

Puerto Rico     Ram6n M. Alonso
               Puerto Rico Geological Survey
                 Division
               Box 5887
               Puerta de Tierra Station
               San Juan, P.R. 00906
               (809)722-2526

Rhode Island    J. Allan Cain
               Department of Geology
               University of Rhode Island
               315 Green Hall
               Kingston, RI02881
               (401) 792-2265
South Carolina Alan-Jon W.Zupan (Acting)
              South Carolina Geological Survey
              5 Geology Road
              Columbia, SC 29210-9998
              (803) 737-9440

 South Dakota C.M. Christensen (Acting)
              South Dakota Geological Survey
              Science Center
             • University of South Dakota
              Vermillion, SD 57069-2390
              (605) 677-5227

    Tennessee Edward T. Luther
              Tennessee Division of Geology
              13th Floor, L & C Tower
              401 Church Street
              Nashville, TN 37243-0445
              (615) 532-1500

        Texas William L. Fisher
              Texas Bureau of Economic Geology
              University of Texas
              University Station, Box X
              Austin, TX 78713-7508
              (512)471-7721

         Utah M. Lee Allison
              Utah Geological & Mineral Survey
              2363 S. Foothill Dr.
              Salt Lake City, UT 84109-1491
              (801)467-7970
               Diane L. Conrad
               Vermont Division of Geology and
                 Mineral Resources
               103 South Main St.
               Waterbury.VT 05671
               (802)244-5164
      Virginia  Stanley S. Johnson
               Virginia Division of Mineral
                 Resources
               P.O. Box 3667
               Charlottesville, VA 22903
               (804)293-5121
   Washington  Raymond Lasmanis
               Washington Division of Geology &
                 Earth Resources
               Department of Natural Resources
               P.O. Box 47007
               Olympia, Washington 98504-7007
               (206) 902-1450
                                               n-35       Reprinted from USGS Open-File Report 93-292

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  West Virginia Larry D. Woodfork
               West Virginia Geological and
                 Economic Survey
               Mont Chateau Research Center
               P.O. Box 879
               Morgantown.WV 26507-0879
               (304)594-2331

Wisconsin      James Robertson
               Wisconsin Geological & Natural
                 History Survey
               3817 Mineral Point Road
               Madison, WI 53705-5100
               (608)263-7384

Wyoming      Gary B. Glass
               Geological Survey of Wyoming
               University of Wyoming
               Box 3008, University Station
               Laramie, WY 82071-3008
               (307)766-2286
                                              n-36
Reprinted from USGS Open-File Report 93-292

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              EPA REGION 4 GEOLOGIC RADON POTENTIAL SUMMARY
                                          by
              Linda C.S. Gundersen, James K. Otton, andR. Randall Schumann
                                 U.S. Geological Survey

       EPA Region 4 includes the states of Alabama, Florida, Georgia, Kentucky, Mississippi,
North Carolina, South Carolina, and Tennessee.  For each state, geologic radon potential areas
were delineated and ranked on the basis of geologic soil, housing construction, and other factors.
Areas in which the average screening indoor radon level of all homes within the area is estimated to
be greater than 4 pCi/L were ranked high.  Areas in which the average screening indoor radon
level of all homes within the area is estimated to be between 2 and 4 pCi/L were ranked
moderate/variable, and areas in which the average screening indoor radon level of all homes within
the area is estimated to be less than 2 pCi/L were ranked low. Information on the data used and on
the radon potential ranking scheme is given in the introduction to this volume. More detailed
information on the geology and radon potential of each state in Region 4 is given in the individual
state chapters.  The individual chapters describing the geology and radon potential of the states in
EPA Region 4, though much more detailed than this summary, still are generalized assessments
and there is no substitute for having a home tested. Within any radon potential area homes with
indoor radon levels both above and below the predicted average will likely be found.
       Major geologic/physiographic provinces for Region 4 are shown in figure 1 and are
referred to in the summary that follows. The moderate climate, use of air conditioning, evaporative
coolers, or open windows for ventilation, and the small proportion of homes with basements
throughout much of Region 4 contribute to generally low indoor radon levels in spite of the fact
that this area has substantial areas of high surface radioactivity.
       Maps showing arithmetic means of measured indoor radon levels are shown in figure 2.
Indoor radon data for Alabama, Georgia, Kentucky, Mississippi, North Carolina, South Carolina,
and Tennessee are from the State/EPA Residential Radon Survey. Data for Rorida are from the
Florida Statewide Radon Study. County screening indoor radon averages range from less than 1
pCi/L to 4.6 pCi/L. The geologic radon potential areas in Region 4 have been summarized from
the individual state chapters and are  shown in figure 3.

ALABAMA

The Plateaus
       The Interior Low Plateaus have been ranked high in geologic radon potential.  The
Mississippian carbonate rocks and shales that underlie this province appear to have high (>2.5 ppm
eU) to moderate (1.5-2.5 ppm elJ) radioactivity associated with them. The carbonates and shales
are also associated with most of the highest county indoor radon averages for the State, particularly
in Colbert, Madison, Lawrence, and Lauderdale Counties. The  geologic units that may be the
source of these problems, as indicated by the radioactivity, appear to be parts of the Fort Payne
Chert, the Tuscumbia Limestone, the Monteagle, Bangor, Pride Mountain, and Parkwobd
Formations, and the Floyd Shale.  Indoor radon levels in homes built on the St. Genevieve
Limestone, Tuscumbia Limestone, and Fort Payne Chert averaged between 3.0 and 4.3 pCi/L.
Soils developed from carbonate rocks are often elevated in uranium and radium. Carbonate soils
are derived from the dissolution of the CaCOs that makes up tiie majority of the rock. When the
CaCOs has been dissolved away, the soils are enriched in the remaining impurities, predominantly
                                          ffl-1     Reprinted from USGS Open-File Report 93-292-D

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Figure 1.  Geologic radon potential areas of EPA Region 4.  See next page for names of
numbered areas.

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 Figure 1 (continued). Geologic radon potential areas of EPA Region 4.  Note: although some
 areas, for example, the Coastal Plain, are contiguous from state to state, they are sometimes
 referred to by slightly different names or are subdivided differently in different states, thus are
 numbered and labelled seperately on this figure.
 l-Jackson Purchase (Coastal Plain)
 2-Western Coalfield
 3-Mississippian Plateau
 4-Eastern Pennyroyal
 5-New Albany Shale
 6-Outer Bluegrass
 7-Inner Bluegrass
 8-Cumberland Plateau (Appalachian Plateau)
 9-Mississippi alluvial plain
 10-Loess-covered Coastal Plain
 11-Eastern Coastal Plain
 12-Cherty Highland
 13-Highland Rim
 14-Nashville Basin
 15-Appalachian Plateau
 16-Ridge and Valley
 17-Unaka Mountains
 18-Blue Ridge Belt
 19-Brevard Fault Zone
20-Chauga Belt
21-Inner Piedmont
22-Kings Mountain Belt
23-Dan River Basin
24-Milton Belt
25-Charlotte Belt
26-Carolina Slate Belt
27-Wadesboro sub-basin
28-Sanford-Durham sub-basins
29-Raleigh Belt
30-Eastem Slate Belt
 31-Inner Coastal Plain
 32-Outer Coastal Plain
 33-Jackson Prairies
 34-Loess Hills
 35-North Central ffills
 36-Flatwoods
 37-Pontotoc Ridge
 38-Black Prairies
 39-Tombigbee Hills
 40-Coastal Pine Meadows
 41-Pine Hills
 42-Interior Low Plateaus
 43-Inner Coastal Plain (Cretaceous)
 44-Northern Piedmont (faults, phylite and granite rocks)
 45-Wedowee and Emuckfaw Groups
 46-Inner Piedmont/Dadeville Complex
 47-Southern Piedmont
48-Inner and Outer Coastal Plain (Tertiary Rocks)
49-Rome-Kingston Thrust Stack
 50-Georgiabama Thrust Stack (north of Allatoona Fault)
 51-Georgiabama Thrust Stack (south of Allatoona Fault)
 52-Little River Thrust Stack
 53-Coastal Plain (Cretaceous/Tertiary)
 54-Coastal Plain (Quaternary/Pliocene-Pleistocene gravels)
 55-Upper Coastal Plain
 56-Middle Coastal Plain
 57-Lower Coastal Plain
 58-Highlands
 59-Lowlands
60-Dade County anomalous area.
                                                ffl-3     Reprinted from USGS Open-File Report 93-292-D

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                                                                       Indoor Radon Screening
                                                                    Measurements: Average (pCi/L)

                                                                         Z3  0.0 to 1.9
                                                                    118 rXTl  2.0 to 4.0
                                                                       17 H  4.1 to 6.0
                                                                       14 U  6.1 to 13.8
                                                                  17« |     "1  Missing Data
                                                                             or < 5 measurements
Figure 2. Screening indoor radon averages for counties with 5 or more measurements in EPA
Region 4. Data for all states in Region4 except Florida from the State/EPA Residential Radon
Survey. Data for Florida are from the Florida Statewide Radon Study. Histograms in map
legend show the number of counties in each category.

-------
                                                                     GEOLOGIC
                                                                  RADON POTENTIAL
                                                                |   | LOW
                                                                H£J MODERATE/VARIABLE
                                                                    HIGH
Figure 3. Geologic radon potential areas of EPA Region 4. For more detail, refer to individual
state radon potential chapters.

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base metals, including uranium. Rinds containing high concentrations of uranium and uranium
minerals can be formed on the surfaces of rocks affected by CaCO3 dissolution and karstification.
Karst and cave morphology is also thought to promote the flow and accumulation of radon.
Because carbonate soils are clayey, they have a tendency to crack when they dry and may develop
very high permeability from the fractures.  Under mu,_,. nditions, however, the soils derived
from carbonates have generally low permeability.
       The Appalachian Plateaus region is ranked moderate in radon potential. Indoor radon is
generally low (< 2 pCi/L) to moderate (2-4 pCi/L). Radioactivity-is low to moderate and soil
permeability is moderate. The sandstone of the Pottsville Formation is not noted for being   .
uranium-bearing, but uraniferous carbonaceous shales interbedded with the sandstone may be the
cause of locally moderate to high (>4 pCi/L) indoor radon.  Cullman County had several indoor
radon measurements greater than 4 pCi/L, including one measurement of 19.8 pCi/L.  Winston and
Walker Counties also had several indoor radon levels greater than 4 pCi/L in the Alabama
Department of Public Health data set.

Valley and Ridge
       The Valley and Ridge province has been ranked moderate in geologic radon potential.
Radioactivity is generally moderate in the Valley and Ridge, with high radioactivity occurring along
the southeastern border with the Piedmont.  Indoor radon is highly variable, with generally low
county averages and one high county average.  Most of the counties had a few readings  greater
than 4 pCi/L. The soils of the Valley and Ridge have low to moderate permeability. The
permeability may be locally high in dry clayey soils and karst areas. Carbonate soils derived from
Cambrian-Ordovician rock units of the Valley and Ridge province cause known indoor radon
problems in eastern Tennessee, western New Jersey, western  Virginia, eastern West Virginia and
central and eastern Pennsylvania. Further, the Devonian Chattanooga Shale crops out locally in
parts of the Valley and Ridge. This shale is widely known to be highly uraniferous and has  been
identified as a source of high indoor radon in Kentucky.

Piedmont
        Where it is possible to associate high radioactivity and/or high indoor radon levels with
particular areas, parts of the Piedmont have been ranked moderate to high in radon potential.
Radiometric anomalies occur over the Talladega Fault zone, which separates the Paleozoic
carbonates from the metamorphic rocks. Some of the metamorphic rocks in the Northern
Piedmont, including the Poe Bridge Mountain Group, the Mad Indian Group, parts of the
Wcdowee Group, and the Higgins Ferry Group, also have high radioactivity associated with them.
In many cases the radiometric anomalies appear to be associated with rocks in fault zones, graphitic
schists and phyllites, felsic gneiss, and other granitic rocks. Furthermore, Talladega, Calhoun,
Cleburne, and Randolph Counties all have some high indoor radon measurements. Uranium in
graphitic phyllite with an assay value of 0.076 percent UsOg has been reported from Cleburne
 County and similar graphitic phyllites from the Georgia Piedmont average 4.7 ppm uranium.
 Graphitic phyllites and schists in other parts of the Piedmont are known sources of radon and have
 high indoor radon levels associated with them. Another source of uranium in Piedmont
 metamorphic rocks is monazite, which contains high amounts of both uranium and thorium. It is a
 common accessory mineral in gneisses and granites throughout the Piedmont and its resistance to
 weathering and high density result in local monazite concentrations in saprolite. A uraniferous
 monazite belt that crosses the Piedmont in northern Chambers and Tallapoosa County may provide
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 a source of radon. Soils of the Northern and Southern Piedmont have moderate to high
 permeability, whereas soils developed from mafic rocks of the Dadeville Complex have low
 permeability. Because the Dadeville Complex consists primarily of mafic rocks with low
 radioactivity and low permeability, the Dadeville Complex was ranked separately from other
 Piedmont rocks and is ranked low in geologic radon potential.

 Coastal Plain
        More than half of Alabama is covered by the sediments of the Coastal Plain. Indoor radon
 levels are generally less than 4 pCi/L and commonly less than 2 pCi/L in this province.  Soil
 permeability is variable-generally low in clays and moderate to high in silts and sands.  A distinct
 radiometric high is located over the central belt of marly sandy clay and chalk known as the Selma
 Group. Within the Selma Group high radioactivity is associated with the Demopolis Chalk,
 Mooreville Chalk, Prairie Bluffs Chalk, and the Ripley Formation in central and western Alabama.
 In eastern Alabama and into Georgia these rocks are dominated by the glauconitic  sands and clays
 of the Providence Sand, Cusseta Sand, and Blufftown Formation. These units have overall
 moderate geologic radon potential.
        As part of a study by the U.S. Geological Survey and the U.S. EPA to assess the radon
 potential of the Coastal Plain sediments in the United States, data on radon in soil  gas, surface
 gamma-ray activity, and soil permeability were collected and examined. Data were collected in the
 Alabama Coastal Plain along a transect running from just north of Montgomery, Alabama, to just
 south of De Funiak Springs, Florida. The highest soil-gas radon concentrations and equivalent
 uranium were found in the Cretaceous Mooreville Chalk, carbonaceous sands and  clays of the
 Providence Sand, and the glauconitic sands of the Eutaw and Ripley Formations.  However,
 permeability in many of these units is slow—generally less than IxlO12 cm2, and soil-gas radon
 was difficult to collect. Geologic units that have the lowest soil-gas radon concentrations and eU
 include the quartz sands of the Cretaceous Gordo Formation and quartz sands and  residuum of the
 undifferentiated upper Tertiary sediments. Low to moderate radon and uranium concentrations
 were measured in the glauconitic sands and clays of the Tertiary Porters Creek Formation and in
 the glauconitic sands, limestones, and clays of the Tertiary Nanafalia, Lisbon Formation, and the
 Tuscahoma Sand. The indoor radon in some counties underlain by the Selma Group is in the 2-4
 pCi/L range with a few measurements greater than 4 pCi/L, higher than in most other parts of the
 Alabama Coastal Plain. High uranium and radon concentrations in the sediments of the Jackson
 Group, locally exceeding 8 ppm U, but generally in the 1-4 ppm U range, and high soil-gas radon
 concentrations, are associated with faults and oil and gas wells in Choctaw County.  Indoor radon
 measurements are generally low in these areas, but may be locally high.

 FLORIDA

       Florida lies entirely within the Coastal Plain, but there are six distinctive areas in Florida for
 which geologic radon potential may be evaluated—the Northern Highlands, Central Highlands, the
 Central and Northern Highlands anomalous areas, the Gulf Coastal Lowlands, Atlantic Coastal'
 Lowlands, and an area here termed the Dade County anomalous area.
       The Northern  Highlands province has generally low geologic radon potential. All counties
entirely within this province have average indoor radon levels less than 1 pCi/L. Leon County
averaged 1.7 and 1.8 pCi/L in the two  surveys of the Florida Statewide Radon Study. Most of
these data likely come from Tallahassee, which lies within an area of moderately elevated eU. This


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a^ea and those parts of southern Columbia, western Union, and northern Alachua County which
are underlain by phosphatic rocks, and limited areas where coarse gravels occur in river terraces in
the western panhandle, are likely to have elevated radon.potential.
       The Central Highlands province has variable geologic radon potential. Generally low
radon potential occurs in low eL areas in th. .astern an  . .uthern parts J> this province. Moderate
radon potential occurs in the western part of this province where uramferous phosphatic rocks are
close to the surface. Localized areas in which uranium contents of soils and shallow subsoils
exceed 100 ppm are likely, and indoor radon levels may exceed 20 PCi/L or more where tins
occSs  Alachua (lies in both the Central and Northern Highlands), Marion, and Sumter Counties
report indoor radon values exceeding 20 pCi/L.  Excessively well-drained hiUslopes may also
                                        generally has low radon potential. High rainfall and
 high water tables cause very moist soils which inhibit radon movement. Equivalent uranium is low
 in most areas except in some coastal bay areas of western peninsular Florida. Some isolated areas
 of elevated radon potential: may occur in these areas of higher eU.
       The Atlantic Coastal Lowland area generally has low radon potential. High rainfall and
 high water tables cause very moist soils that inhibit radon movement. Equivalent uranium is low in
 n£* roas In some beach sand areas in northern Florida, elevated eU seems to be associated with
 heavy minerals; however, there is no evidence to suggest that elevated indoor radon occurs in these
        An area in southwestern Dade County, underlain by thin sandy soils covering shallow
 limestone bedrock, has equivalent uranium values as high as 3.5 ppm. Unusually high levels of
 radium are present in soils formed on the Pleistocene Key Largo Limestone, and perhaps on other
 rock formations in certain areas of the Florida Keys and in southwestern Dade County. Areas of
 elevated eU and elevated indoor radon in Dade County are likely related to these unusual soils.
 These soils may be responsible for the modestly elevated eU in soils and for the elevated indoor
 radon levels, and they may extend into Collier County as well.
 GEORGIA
       "rhe'oldest rocks in Georgia form the mountains and rolling hills of the Blue Ridge
  Province and most of the Piedmont Province. These highly deformed rocks are separated by a
  series of thrust faults superimposing groups of older rocks over younger rocks, comprising; the
  Georgiabama Thrust Stack. The igneous and metamorphic rocks in the Georgiabama Thrust Stock
  north of the Altoona Fault have been ranked moderate overall in geologic radon potential, but the
  radon potential of the area is variable. Mafic rocks are expected to have low radon potential
  whereas phyllite, slate, some metagraywacke, granitic gneiss and granite have moderate to high
  radon potential. Soil permeability is slow to moderate in most soils.  Counties in this area have
  average indoor radon levels that vary from low to high « 1 pCi/L to > 4 pCi/L) but the
  measurements are predominantly in the moderate range. The highest indoor radon reading, 18.7
  pCi/L  was measured in the northern Blue Ridge in Fannin County, which is underlain
  predominantly by metagraywacke, slate, phyllite, and mica schists. Equivalent uranium
  concentrations in rocks and soils of this area are moderate to high.                 ,.,,,«.
         The Georgiabama Thrust Stack south of the Alatoona Fault has also been ranked moderate
  in geologic radon potential. The majority of this part of the Georgiabama Thrust Stack is underlain


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 by schist and amphibolite of the Zebuloh sheet, which have generally low radioactivity where not
 intruded by granites or where not highly sheared, particularly south of the Towaliga Fault.  An area
 with distinctly low aeroradiometric readings which is underlain by mafic metamorphic rocks lies
 between the Brevard and Allatoona Faults in the northwestern Georgiabama Thrust Stack.  All of
 uxes>e rocks have slow to moderate permeability, and inuoor radon values are generaJy low to
 moderate.  A central zone of biotite gneiss, granitic gneiss, and granite has elevated uranium
 concentrations and high equivalent uranium (>2.5 ppm) on the NURE map. Soil permeability is
 generally low to locally moderate.  Indoor radon levels are generally moderate. Recent soil-gas
 radon studies in the Brevard zone and surrounding rocks show that this zone may yield unusually
 high soil-gas radon where the zone crosses the Ben Hill and Palmetto granites. Surface gamma-
 ray spectrometer measurements yielded equivalent uranium from 4 to 17 ppm over granite and
 granitic biotite gneiss (Lithonia gneiss). Soil-gas radon concentrations commonly exceeded 2,000
 pCi/L and the highest soil-gas radon measured was 26,000 pCi/L in faulted Ben Hill granite.
 Undeformed Lithonia gneiss had average soil radon of more than 2,000 pCi/L. Mica schist
 averaged less than 1,000 pCi/L where it is undeformed. The Stone Mountain granite and mafic
 rocks yielded low soil-gas radon. The Grenville Basement granite and granite gneiss have
 moderate to locally high radon potential. Radioactivity is generally moderate to high and soil
 permeability is generally moderate.
       The Little River Thrust Stack is generally low to moderate in geologic radon potential. It is
 underlain primarily by mafic metamorphic rocks with low radon potential, but each belt contains
 areas of rocks with moderate to locally high radon potential. Metadacites have moderate radon
 potential and moderate radioactivity. Faults and shear zones have local areas of mineralization and
 locally high permeability. Granite intrusives may also have moderate radon potential.
 Aeroradioactivity is generally low and soil permeability is generally moderate.

 Ridge and Valley
       The Rome-Kingston Thrust Stack is ranked low in geologic radon potential; however,
 some of the limestones and  shales in this area may have moderate to high radon potential. Indoor
 radon is variable but generally low to moderate.  Permeability of the soils is low to moderate.
 Equivalent uranium is moderate to locally high, especially along the Carters Dam and Emerson
 faults.  Carbonate soils of the Valley and Ridge Province are likely to cause indoor radon
 problems. The Devonian Chattanooga Shale, which crops out locally in parts of the Valley  and
 Ridge, is highly uraniferous and has been identified as a source of high indoor radon levels in
 Kentucky. Numerous gamma radioactivity anomalies are  associated with the Pennington
 Formation, Bangor Limestone, Fort Paine Chert, Chattanooga Shale, Floyd Shale, the Knox
 Group, and the Rome Formation.

Appalachian Plateau
       The Appalachian Plateau has been ranked low in geologic radon potential.  Sandstone is the
 dominant rock type and it generally has low uranium concentrations. Equivalent uranium is low to
 moderate. Permeability of the soils is moderate and indoor radon levels are low.

 Coastal Plain
       The Coastal Plain has been ranked low in radon potential, but certain areas of the Coastal
Plain in which glauconitic, carbonaceous, and phosphatic sediments are abundant may have
moderate geologic radon potential.  The highest soil-gas radon concentrations (>1000 pCi/L) and
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equivalent uranium (eU) concentrations (>2 ppm) in studies of radon in soil-gas in the Coastal
Plain of Alabama were found in the carbonaceous sands and clays of the Providence Sand and the
glauconitic sands of the Eutaw and Ripley Formations. Low to moderate soil-gas radon and
uranium concentrations were measured in the glauconitic sands, limestones, and clays of the
Tertiary Nanafalia and Lisbon Formations, and the Tuscahoma Sand. Equivalent rock units in
Georgia are also likely to be sources of high radon levels.  Equivalent uranium is moderate in the
Cretaceous and Tertiary-age sediments" and low, with local highs, in the Quaternary sediments.
Radioactivity highs in much of the Coastal Plain are related to phosphate and heavy-mineral
concentrations. In the shoreline complexes and in several sediment units such as the Hawthorn
Formation, the phosphate concentrations are naturally occurring. In the Black Lands and in many
portions of the central Coastal Plain that have abundant agricultural activity, the radioactivity may
be related to the use of phosphate fertilizers. Indoor radon in the Coastal Plain is generally low.

KENTUCKY
       Three primary areas in Kentucky are identified as being underlain by rock types and
geologic features suspected of producing elevated radon levels:  (1) areas underlain by Devonian
black shales in the Outer Bluegrass region; (2) areas underlain by the Ordovician Lexington
Limestone, particularly the Tanglewood Member, in the Inner Bluegrass region; and (3) areas of
the Mississippian Plateau underlain by karsted limestones or black shales.  In addition, some
homes underlain by, or in close proximity to, major faults in the Western Coalfield and Inner
Bluegrass regions may have locally elevated indoor radon levels due to localized concentrations of
radioactive minerals and higher permeability in fault and fracture zones.
Appalachian Plateau
       The black shale and limestone areas in the Mississippian Plateau region have associated
high surface radioactivity, and the Western Coalfield  contains scattered radioactivity anomalies.
The arcuate pattern of radioactivity anomalies along the southern edge of the Outer Bluegrass
region corresponds closely to the outcrop pattern of the New Albany Shale.  A group of
radiometric anomalies in the vicinity of Warren and Logan counties appears to correspond to
outcrops of the Mississippian Ste. Genevieve and St. Louis Limestones. The clastic sedimentary
rocks of the Cumberland Plateau region are characterized by relatively low surface radioactivity and
generally have low indoor radon levels.
       In the Mississippian Plateau Region, locally elevated indoor radon levels are likely in  areas
with high soil permeability, solution cavities, or localized concentrations of radioactive minerals in
karst regions, and in areas underlain black shale along the State's southern border.  Of particular
 concern are the Devonian-Mississippian Chattanooga Shale (equivalent to the New Albany Shale),
 limestones in the Mississippian Fort Payne  Formation, and the Mississippian Salem, Warsaw,
 Harrodsburg, St. Louis, and Ste. Genevieve Limestones in south-central Kentucky.
        Caves, produced by limestone solution and relatively common in central Kentucky, are
 natural concentrators of radon and can be a local source of high radon levels. Levels of radon
 decay products approaching a maximum of 2.0 working levels (WL), which corresponds to about
 400 pCi/L of radon (assuming that radon and its decay products are in 50 percent equilibrium), and
 averaging about 0.70 WL, or about 140 pCi/L of radon, have been recorded in Mammoth Cave.
 Although  these levels are not considered hazardous  if the exposure is of short duration, such as
 would be experienced by a visitor to the cave, it could be of concern to National Park Service
 employees and other persons that spend longer periods of time in the caves. Another potential
 hazard is the use of cave air for building air temperature control, as was formerly done at the


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 Mammoth Cave National Park visitor center. The cave air, which averages 54°F, was pumped into
 the visitor center for cooling, but this process has been discontinued due to the relatively high
 radioactivity associated with the cave air.

 Coastal Plain
        The majority of homes in the Jackson Purchase Region (Coastal Plain) have low indoor
 radon levels, although the area is underlain in part by loess with an eU signature in the 2.0-3.0
 ppm range. The poor correspondence with surface radioactivity in this area appears to be due to a
 combination of low soil permeability and high water tables.  The Coastal Plain is the only part of
 the State in which seasonal high water tables were consistently listed in the SCS soil surveys as
 less than 6 ft, and commonly less than 2 ft.

 MISSISSIPPI

        Examination of the available data reveals that Mississippi is generally an area of low radon
 potential. Indoor radon levels in Mississippi are generally low; however, several counties had
 individual homes with radon levels greater than 4 pCi/L.  Counties with maximum levels greater
 than 4 pCi/L are concentrated in the northeastern part of the State within the glauconitic and
 phosphatic sediments of the Tombigbee Hills and Black Prairies.  Readings greater than 4 pCi/L
 also occur in the Mississippi Alluvial Plain, the eastern part of the Pine Hills Province, and in
 loess-covered areas.  Glauconitic and phosphatic sediments of the Coastal Plain, particularly the
 Cretaceous and lower Tertiary-age geologic units located in the northeastern portion of the State,
 have some geologic potential to produce radon.  Based on radioactivity and studies of radon in
 other parts of the Coastal Plain, the Black Prairies and Pontotoc Ridge have been  assigned
 moderate geologic radon potential; all other parts of Mississippi are considered to be low in
 geologic radon potential. The climate, soil, and lifestyle of the inhabitants of Mississippi have
 influenced building construction styles and building ventilation which, in general, do not allow
 high concentrations of radon to accumulate.

 Coastal Plain
       A study of the radon in the Coastal Plain of Texas, Tennessee, and Alabama suggests that
 glauconitic, phosphatic, and carbonaceous sediments and sedimentary rocks, equivalent to those in
 Mississippi, can cause elevated levels of indoor radon. Ground-based surveys of radioactivity and
 radon in soils in that study indicate that the Upper Cretaceous through Lower Tertiary Coastal Plain
 sediments are sources of high soil-gas radon (> 1,000 pCi/L) and soil uranium concentrations.
 The high equivalent uranium found over the Coastal Plain sediments in northeastern Mississippi
 supports the possibility of a similar source of high radon levels.  Chalks, clays and marls tend to
 have low permeability when moist and higher permeability when dry due to desiccation fractures
and joints.
       The youngest Coastal Plain sediments, particularly Oligocene and younger, have
decreasing amounts of glauconite and phosphate and become increasingly siliceous and therefore
less likely to be significant sources of radon. Some carbonaceous units may be possible radon
 sources.
       Loess in Tennessee, and probably elsewhere, is known to generate high levels of radon in
both dry and saturated soils.  Both thin and thick loess units can easily be traced on the
                                           DI-11    Reprinted from USGS Open-File Report 93-292-D

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radioactivity map of Mississippi by following the highest of the moderate equivalent uranium
anomalies. Loess tends to have low permeability when moist and higher permeability when dry.

Mississippi Alluvial Plain
       The Mississippi Alluvial Plain contains several areas with locally high eU, as well as
having moderate radioactivity overall. These high eU areas are located close to the river in Bolivar
and Washington Counties. The highest indoor radon level recorded in Mississippi in the
State/EPA Residential Radon Survey (22.8 pCi/L) occurs within Bolivar County and the second
highest radon level of homes measured to date in the State (16.1 pCi/L) occurs in Washington
County.  It is not apparent from the data available whether the high eU and indoor radon levels are
correlative, and only a few indoor radon readings in each county are greater than 4 pCi/L. The
geology of the region is not generally conducive to high uranium concentrations, except possibly in
heavy-mineral placer deposits.  Further, elevated radioactivity in the Mississippi Alluvial Plain may
be due in part to uranium in phosphatic fertilizers. Locally high soil permeability in some of the
alluvial sediments may allow locally high indoor radon levels to occur.
       The southeastern half of Mississippi has low radioactivity and low indoor radon levels.
The few indoor radon readings greater than 4 pCi/L were between 4.1 and 5.8 pCi/L.  The lowest
eU is associated with the coastal deposits and the CitroneUe Formation, which are predominantly
quartz sands with low radon potential. Slightly higher eU, though still low overall, is associated
with the Pascagoula and Hattiesburg Formations and Catahoula Formation.  Soils in this area are
variably poorly to well drained with slow to moderate permeabilities.
       The Chattanooga Shale and related sedimentary rocks in the northeastern part of the State
have the potential to be sources of high indoor radon levels. In Tennessee and Kentucky, the
Chattanooga Shale has high uranium concentrations and is associated with high indoor radon levels
in those states. The extent of these rocks in Mississippi is minor.

 NORTH CAROLINA

 Blue Ridge                                                                      . .
        The Blue Ridge has been ranked moderate overall in geologic radon potential, but it is
 actually variably moderate to high in radon potential. The province has highly variable geology
 and because of the constraints imposed by viewing the indoor radon data at the county level, it is
 impossible to assign specific geologic areas of the Blue Ridge to specific moderate or high indoor
 radon levels.  Average indoor radon levels are moderate (2-4 pCi/L) in the majority of counties.
 However, two counties have indoor radon averages between 4.1  and 6 pCi/L (Cherokee and
 Buncomb Counties) and three counties in the northern Blue Ridge (AUeghany, Watauga, and
 Mitchell) have indoor radon averages greater than 6 pCi/L. These three counties are generally
 underlain by granitic gneiss, mica schist, and minor amphibolite and phyllite. Transylvania and
 Henderson Counties, which are underlain by parts of the Blue Ridge and Inner Piedmont, also
 have indoor radon averages greater than 6 pCi/L.  The Brevard fault zone, Henderson Gneiss, and
 Ceasars Head Granite are possible sources of high indoor radon in these two counties. Equivalent
 uranium is variable from low to high in the Blue Ridge. The highest eU appears to be associated
 with the Ocoee Supergroup in the southern Blue Ridge, rocks in the Grandfather Mountain
 Window, and metamorphic rocks in parts of Haywood and Buncomb Counties. Soils are
 generally moderate in permeability.
                                            m-12    Reprinted from USGS Open-File Report 93-292-D

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        The Chauga belt and Brevard fault zone are. ranked high in geologic radon potential.  The
 Chauga belt consists predominantly of the Henderson Gneiss.  High eU and high uranium in
 stream sediments appears to be associated with the Brevard fault zone, Henderson Gneiss, and
 Ceasars Head Granite in this area. Average indoor radon levels in the two counties that the main
 part of the Chauga belt and the southern portion of the Brevard fault zone passes through are high.
 The soils have moderate permeability.

 Piedmont                           ,  .
        The Inner Piedmont and Kings Mountain belts have been ranked moderate in geologic
 radon potential. Indoor radon levels are generally moderate. Granitic plutons, granitic gneiss,
 monazite-rich gneiss and schist, pegmatites, and fault zones appear to have high eU and high
 uranium concentrations  in stream sediment samples.  Many of the granitic plutons are known to be
 enriched in uranium and recent studies suggest that the soils developed on many of the uraniferous
 granitic plutons and related fault zones in the Blue Ridge and Piedmont are possible sources of
 radon.  Measured soil-gas radon concentrations commonly exceeded 1,000 pCi/L in soils
 developed on the Cherryville Granite, RolesviUe Suite, and the Sims, Sandy Mush, and Castalia
 plutons. Soils developed on the Rocky Mount, Spruce Pine, Toluca, Mt. Airy, and Stone
 Mountain plutons had relatively low soil-gas radon concentrations. Soil permeabilities in the Inner
 Piedmont, Brevard fault zone, and Kings Mountain belt are variably low to moderate which,
 together with the large proportion of homes without basements, may account for the abundance of
 moderate indoor radon levels.
        Most shear zones in the Piedmont and Blue Ridge should be regarded as having the
 potential to produce very localized moderate to high indoor radon  levels. Geochemical and
 structural models developed from studies of shear zones in granitic metamorphic and igneous rocks
 from the Reading Prong  in New York to the Piedmont in Virginia  indicate that uranium
 enrichment, the redistribution of uranium into the rock foliation during deformation, and high
 radon emanation, are common to most shear zones. Because they are very localized sources of
 radon and uranium, shear zones may not always be detected by radiometric or stream sediments
 surveys.
       The Charlotte belt has been ranked low in geologic radon potential but it is actually quite
 variable-dominantiy low in the southern portion of the belt and higher in the northern portion of
 the belt Equivalent uranium is generally low, with locally high eU occurring in the central and
 northern portions of the  belt, associated with the Concord and Salisbury Plutonic Suites.
 Permeability of the soils is generally low to moderate and indoor radon levels are generally low.
       The Carolina slate belt has been ranked low in radon potential where it is underlain
 primarily by metavolcanic rocks.  Where it crops out east of the Mesozoic basins it has been ranked
 moderate. Aeroradioactivity over the Carolina slate belt, uranium in stream sediment samples, and
 indoor radon levels are markedly low. Permeability of many of the metavolcanic units is generally
 low to locally moderate.  East of the Wadesboro subbasin in Anson and Richmond Counties lies a
 small area of the slate belt that is intruded by the Lilesville Granite and Peedee Gabbro. It has high
 eU and high uranium concentrations in stream sediments, and moderate to high permeability in the
 soils, and is a likely source of moderate to high indoor radon levels.
       The Raleigh belt  has been ranked moderate in geologic radon potential.  Equivalent uranium
in the Raleigh belt is .generally moderate to high and appears to be associated with granitic intrusive
rocks, including the Castalia and Wilton plutons and the RolesviUe Suite.  A belt of monazite-
bearing  rocks also passes through the Raleigh belt and may account for part of the observed high


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radioactivity. Soils have variably low to" moderate permeability. Indoor radon levels are generally
moderate.

Coastal Plain
       In the Coastal Plain province, moderate to hi^l.  .  Is associated with the Cretaceous and
Tertiary sediments of the Inner Coastal Plain.  Permeability of the soils is highly variable but
generally moderate to low, and may be locally high in sands  and gravels. Seasonally high water
tables are common.  Indoor radon levels in the Coastal Plain  are generally low. The Inner Coastal
Plain is ranked low in geologic radon potential but may be locally moderate to high, especially in
areas underlain by Cretaceous sediments. Glauconitic, phosphatic, monazite-rich, and
carbonaceous sediments and sedimentary rocks in the Coastal Plain of Texas, New Jersey, and
Alabama, similar to some Coastal Plain sediments in North Carolina, are the source for moderate
indoor radon levels seen in parts of the Inner Coastal Plain of these states.
       The Outer Coastal Plain has low eU, low indoor radon levels, and is generally underlain by
sediments with low uranium concentrations. Soil permeability is variable but generally moderate.
Seasonally high water tables are common.  A few isolated areas of high radioactivity in the Outer
Coastal Plain may be related to heavy mineral and phosphate deposits in the shoreline sediments.
The area has been ranked low in geologic radon potential, but may have local moderate or high
indoor radon occurrences related to heavy minerals or phosphate deposits.

SOUTH  CAROLINA

Blue Ridge and Piedmont
       The Blue Ridge and Piedmont Provinces have moderate geologic radon potential.  Possible
sources of radon include uraniferous granites, biotite and granitic gneiss, and shear zones. Soils
developed on many of the uraniferous granitic plutons and some fault zones within the Piedmont
and Blue Ridge of North and South Carolina yield high soil-gas radon (>1,000 pCi/L).  In the
Blue Ridge, sheared graphitic rocks may be a local source for high indoor radon concentrations.
       More than 10 percent of the homes tested in Greenville and Oconee Counties, in the Blue
Ridge and Piedmont, have indoor radon levels greater than 4 pCi/L. Greenville County also has
the highest indoor radon measurement in the State, 80.7 pCi/L, the highest radioactivity, associated
with the  Silurian-Devonian Ceasers Head Granitic Gneiss, and with biotite  gneiss in the Carolina
monazite belt. In Oconee County, the Toxaway Gneiss and  graphitic rocks in the Brevard Fault
Zone may account for the higher incidence of indoor radon levels exceeding 4 pCi/L and the higher
overall indoor radon average of the county. Average indoor radon levels in the Blue Ridge and
Piedmont are generally higher than in the rest of the State, and moderate to  high radioactivity is
common. Most of the soils formed on granitic rocks have moderate permeability and do not
represent an impediment to radon mobility. Mafic rocks in the Blue Ridge  and Piedmont have low
radon potential.  These rocks have low concentrations of uranium, and soils formed from them
have low permeability.

Coastal Plain
       In the Coastal Plain Province, moderate to high radioactivity is associated with the
Cretaceous and Tertiary sediments of the upper Coastal Plain. Glauconitic, phosphatic, monazite-
rich, and carbonaceous sediments and sedimentary rocks in the Coastal Plain of Texas, New
Jersey, and Alabama, similar to some of those in South Carolina, cause elevated levels of indoor
                                           ffl-14    Reprinted from USGS Open-File Report 93-292-D

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 radon.  Orangeburg County is the only other county besides Greenville and Oconee Counties that
 has an average indoor radon level greater than 2 pCi/L. It is underlain by Lower Tertiary
 sediments in an extremely dissected part of the Coastal Plain.  Radioactivity is moderate to low.
 Soils are highly variable in the county because of the complicated erosion patterns. The few high
 values of indoor radon for this county create an overall higher indoor radon average for the county.
 These locally high readings may be due to local accumulations of monazite, glauconite, or
 phosphate that can occur within these particular sediments.
        The lower Coastal Plain has low to locally high radioactivity and low indoor radon levels.
 Most of the sediments have low uranium concentrations with the exception of the uraniferous,
 phosphatic sediments of the Cooper Group and local, heavy-mineral placer deposits within some
 of the Quaternary units. The area has been ranked low in geologic radon potential overall, but the
 radon potential may be locally high in areas underlain by these uraniferous sediments.

 TENNESSEE

 Coastal Plain and Mississippi Alluvial Plain
        The Mississippi Alluvial Plain has low geologic radon potential. The high soil moisture,
 high water tables, and the lack of permeable soils lower the radon potential in spite of moderate elJ
 values.  Some areas with very sandy or excessively-drained soils may cause homes to have indoor
 radon levels exceeding 4 pCi/L.
        The loess-covered parts of the Coastal Plain have low radon potential in spite of moderate
 ell values and elevated soil-gas radon concentrations.  The radon potential is lowered by the high
 moisture content and low permeability of the soils. The lack of basements in homes also lowers
 the potential. If prolonged dry periods were to occur in this area, some homes might see a
 significant increase in indoor radon, especially those with basements or crawl spaces. The eastern
 Coastal Plain has moderate geologic radon potential. NURE data show elevated elJ values
 compared to the rest of the Coastal Plain. Soil-gas radon levels are locally elevated.

 Highland Rim and Nashville Basin
       The Highland Rim and Nashville Basin are underlain by sedimentary rocks of Paleozoic
 age, principally limestone, shale, chert, and dolostone. The part of the Highland Rim that is
 underlain by cherry limestone (Fort Payne Formation) has high geologic radon potential. This area
 has moderate to locally high eU and soils that are cherty and excessively well drained.  The
 limestone and shale part of the Highland Rim has moderate radon potential. The Nashville Basin
 has high geologic radon potential.  The elevated eU, the presence of abundant phosphatic soils,
 local karst, and the presence of generally well-drained soils all contribute to this high geologic
 radon potential. Very high (>20 pCi/L)  to extreme indoor radon values (>200 pCi/L) are possible
 where homes are sited on soils developed on the Chattanooga shale, on phosphate-rich residual
 soils, or on karst pinnacles.

Appalachian Plateau
       Sandstones and shales underlie most of the Appalachian Plateau, which generally has
 moderate geologic radon potential.  These rocks are typically not good sources of radon and values
 for eU are among the lowest in the State. However, many sandy, well-drained to excessively-
 drained soils are present in this region, and may be a source of locally elevated radon levels
 because of their high permeability.
                                           m-15    Reprinted from USGS Open-File Report 93-292-D

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Ridge and Valley
       Folded and faulted Paleozoic limestone, shale, chert, dolostone, and sandstone underlie
most of the Ridge and Valley region, with sandstone and cherty dolostone forming most of the
ridges and limestone and shale forming mo- of the val  ,  . The Ridge ~nd Valley region has high
geologic radon potential because of elevated eU values, karst, and well drained soils.  Very high
(>20 pCi/L) to extreme indoor radon values (>200 pCi/L) are possible where homes are sited on
soils developed on black shales, phosphate-rich residual soils, or karst pinnacles. Homes with
basements are more likely to yield elevated indoor radon levels than homes with slab-on-grade
construction.

Unaka Mountains
       The Unaka Mountains are underlain by siltstone, sandstone, conglomerate, quartzite,
phyllite, gneiss, granite, and metamorphosed volcanic rocks of Precambrian and Paleozoic age that
have moderate geologic radon potential. Values of eU are generally moderate, although they are
locally high.  Some very high (>20 pCi/L) to extreme (>200 pCi/L) indoor radon levels are
possible where homes are sited on phosphate-rich residual soils developed on phosphatic carbonate
rocks, or on pegmatite in  the metamorphic rock areas, but the former are much less common in this
region than in the Nashville Basin and the Ridge and Valley region.
                                            m-16    Reprinted from USGS Open-File Report 93-292-D

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      PRELIMINARY GEOLOGIC RADON POTENTIAL ASSESSMENT OF KENTUCKY
                                            by
                                   R. Rdndall Schumann
                                  U.S. Geological Survey

 INTRODUCTION

        Kentucky's geology is diverse.  The geology, physiography, soils, and surface
 radioactivity of Kentucky are interrelated, with bedrock geology as the primary controlling factor.
 Much of Kentucky has low to moderate geologic radon potential.  Areas with a high radon
 potential include those areas underlain by phosphatic limestones in the Inner Bluegrass Region,
 areas underlain by uranium-bearing black shales on the outer margin of the Outer Bluegrass Region
 and locally along the State's southern border, and some areas underlain by karst limestones in the
 south-central part of the State.
        This is a generalized assessment of geologic radon potential of rocks, soils, and surficial
 deposits of Kentucky. The scale of this assessment is such that it is inappropriate for use in
 identifying the radon potential of small areas such as neighborhoods, individual building sites, or
 housing tracts. Any localized assessment of radon potential must be supplemented with additional
 data and information from the locality.  Within any area of a given radon potential ranking, there
 are likely to be areas with higher or lower radon levels than characterized for the area as a whole.
 Indoor radon levels, both high and low, can be quite localized, and there is no substitute for testing
 individual homes.  Elevated levels of indoor radon have been found in every state, and EPA
 recommends that all homes be tested. For more information on radon, the reader is urged to
 consult the local or State radon program or EPA regional office. More detailed information on state
 or local geology may be obtained from the State geological survey. Addresses and phone numbers
 for these agencies are listed in chapter 1 of this booklet

 PHYSIOGRAPHIC AND GEOGRAPHIC SETTING

       The physiography of Kentucky (fig. 1) is closely related to its underlying geology (fig. 2).
 The areas shown on the physiographic map (fig. 1) are subdivisions of larger physiographic
 provinces encompassing parts of several states each.  The Cumberland Plateau in eastern Kentucky
 is part of the Appalachian Plateaus province. The Jackson Purchase is part of the Coastal Plain
 province. The central part of the State falls mainly in the Interior Plateaus region of the Interior
 Lowlands province.
       The physiographic regions of Kentucky are characterized by dissected plateaus and rolling
 plains separated by scarps (Newell, 1986). Some of the region names are descriptive of landscape
 features, such as the plateaus, while the names of other areas, such as the Western Coalfield,
 Jackson Purchase, and Bluegrass Region, are of social-political or economic origin. The different
 landforms that characterize each region are derived from weathering and erosion of the gently
 dipping clastic or carbonate sedimentary rocks that underlie them.  Karst topography is common in
 the carbonate rocks that underlie the Bluegrass and Mississippian Plateau regions.  The Western
 Coalfield and Cumberland Plateau are dissected uplands underlain primarily by clastic sedimentary
rocks. The Jackson Purchase is a low-lying part of the Mississippi Embayment of the Gulf
 Coastal Plain that is underlain primarily by sand and gravel river deposits (Newell, 1986).
       Land use, industry, and lifestyles affect population density  (fig. 3) and housing types in
each region. The Jackson Purchase region is primarily agricultural in the alluvial valleys of the

                                          IV-1    Reprinted from USGS Open-File Report 93-292-D

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Mississippi and Ohio Rivers, but includes several small urban centers and .one large one, Paducah,
a shipping port, railway center, and power generating center on the Ohio River.  Coal mining is a
major industry in the Western Coalfield and Cumberland Plateau regions. Manufacturing and
agriculture are also important in the Western Coalfield. The Mississippian Plateau region contains
many small to moderate-sized urban centers in which most of the people in the region work and
live, although farming is also important throughout this area. Tobacco and livestock are two of the
major agricultural commodities of this region. The Bluegrass region is the most densely populated
area in the State and contains the major metropolitan areas of Louisville and Lexington.
Kentucky's Bluegrass Region is well known for its horses, distilleries, and tobacco and cattle
industries. The Cumberland Plateau is a mountainous region covering about 25 percent of the
State's total area. The dominant industries in this region are coal mining and lumber production.
The population density in this region is below the State average, and although the population is
mostly rural, it is largely non-agricultural (Mather, 1977).
       Housing characteristics are of importance in estimating indoor radon potential because the
age and condition, presence or absence of a basement, and air exchange rate of a house influence
the rate of radon entry from the underlying soil and whether radon will build up or quickly
dissipate within the structure.  Housing age and value (fig. 4) provide a rough indicator of house
condition and general construction characteristics, suggesting that, for example, newer, higher-cost
houses in the Bluegrass Region are probably built "tighter" and are more likely to allow radon  to
build up than most older homes in the Cumberland Plateau Region.

GEOLOGY

        The following discussion is partly condensed from McDowell (1986) and McGrain (1983).
The geologic map (fig. 2) is generalized from McDowell and others (1981), Cressman (1973), and
Winsor and Bailey (1964).
        AU of Kentucky is underlain by sedimentary deposits (fig. 2). The oldest rocks exposed in
the State are limestones and dolomites of Ordovician age. These rocks are exposed primarily in the
Bluegrass Region of north-central Kentucky.  Virtually all of the Inner Bluegrass Region is
underlain by Ordovician limestones, dolomites, and thin interbedded shales of the High Bridge
Group and Lexington Limestone. Some of the limestones are phosphatic, a notable example being
the Tanglewood Member of the Lexington Limestone, which contains an average of 2.4 percent
P2O5. Phosphate is commonly associated with uranium in carbonate rocks and soils, which may
 account for the slightly higher radiometric signature of the Lexington Limestone compared with
 surrounding rocks (fig. 5).  The Outer Bluegrass Region is underlain predominantly by limestone
 and shale of Ordovician to  Devonian age.  Karst topography (caves, sinkholes, springs,
 disappearing streams) is formed on the limestones in this area but the sinkholes and caves are  not
 as numerous or as large as those in the Mississippian Plateau Region to the south.  Of particular
 note in this area are the Devonian-Mississippian New Albany Shale and the Chattanooga and Ohio
 Shales, which are equivalent to the New Albany Shale. These distinctive, organic-rich black
 shales are exposed  along the margin of the Outer Bluegrass Region (fig. 2) and along the southern
 border of the State and range in thickness from a few feet in south-central Kentucky to as much as
 1000 feet along the west flank of Pine Mountain in eastern Kentucky. The New Albany black
 shale and its equivalents typically contain 15-30 parts per million (ppm) uranium (Provo and
 others, 1977) and have the  best potential low-grade uranium resources of any black shale in the
 United States (Geodata International, 1980).  The outcrop pattern of the black shale has a

                                            IV-5     Reprinted from USGS Open-File Report 93-292-D

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A.
     Percent of housing constructed
        since 1950 (1974 data)
     n
         0.0 to 29.9
         30.0  to 39.9
         40.0  to 49.9
         50.0  to 100.0
B.
      Median housing value
        in dollars (1974)
     (3
          Oto 6999
          7000  to 8499
          8500  to 10999
          11000  to 12999
          13000  to 19000
         Figure 4. Median housing age and cost (after Phillips, 1977).

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 distinctive radiometric signature, forming an arcuate pattern of anomalies in the north-central part
 of the State (fig. 5).
       The Mississippian Plateau Region is underlain almost entirely by Mississippian-age marine
 limestones and dolomites and marginal marine sandstones, siltstones, and shales.  The most
 common rock type in this area is limestone, and karst topography is also common. Limestones in
 the Fort Payne Formation and the Salem, Warsaw, Harrodsburg, St. Louis, and Ste. Genevieve
 Limestones form extensive karst plains and exhibit numerous sinkholes, caves, and disappearing
 streams in western, west-central, and south-central Kentucky.
       The Cumberland Plateau and Western Coalfield regions are underlain primarily by
 Pennsylvanian sandstones, siltstones, and shales. Coal beds and thin marine shale and limestone
 units also occur in these areas. Pennsylvanian strata probably once formed a continuous layer
 across the State, but erosion on the Cincinnati Arch, which separates the two basins, has removed
 hundreds, and perhaps thousands of feet of strata, resulting in the present outcrop pattern.
 Whereas most of the marine sequences in the Cumberland Plateau Region are shales, those in the
 Western Coalfield are largely limestones that include shale, siltstone, and coal beds.
       The Jackson Purchase is underlain by Cretaceous and Tertiary unconsolidated marine and
 continental gravels, sands, silts, and clays, many of which are overlain by younger alluvium and
 loess. Loess deposits in the Mississippi and Ohio valleys are locally as much as 65 feet thick, but
 are commonly in the range of 5 to 20 feet in much of western Kentucky. Discontinuous deposits
 of glacial outwash and till occur in the northernmost part of the State along the Ohio River.

 SOILS

       A generalized soil permeability map (fig. 6) was compiled from a soil association map
 (fig. 7) and county soil surveys published by the U.S. Soil Conservation Service (SCS).  In
 general, most soils in Kentucky have low or moderate permeability. Some areas underlain by
 limestones may have locally increased permeability because solution cavities are present. Soils
 formed on the Lexington Limestone, in the Inner Bluegrass region, have a significantly higher
 permeability than soils in the surrounding Outer Bluegrass region. Most of the Jackson Purchase
 and the northern part of the Western Coalfield have water tables within three feet of the ground
 surface seasonally (fig. 7). Large alluvial valleys such as those areas bordering the Mississippi,
 Ohio, and Kentucky Rivers may have local, seasonally high water tables that would impede soil
 gas movement and generally reduce soil-gas radon levels during those periods.

 INDOOR RADON DATA

       Figure 8 shows indoor radon data from 879 homes tested in the State/EPA Residential
 Radon Survey conducted during the winter of 1986-87.  Data from only those counties in which
 five or more measurements were made are shown here (a map of county locations  and names is
 shown in figure 9). The data for all counties in which any indoor radon tests were made in  the
 State/EPA survey are summarized in Table 1.  In this discussion, "elevated" indoor radon levels
refers to screening indoor radon levels greater than 4.0 pCi/L. The statewide radon average in this
 survey was 2.8 pCi/L and 17.9 percent of the homes tested in the State had screening indoor
radon levels exceeding 4 pCi/L. The highest indoor radon measured in the survey was 65.5 pCi/L
in Bullitt County.
                                          IV-8    Reprinted from USGS Open-File Report 93-292-D

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  FIGURE 7 (continued). MAJOR SOIL ASSOCIATIONS OF KENTUCKY
          (fromBladen and Bailey, 1977; Winsor and BaUey, 1964; and SCS county soU surveys)
 	AREA
  1. Purchase-Mississippi
       IMPORTANT
       SOIL SERIES
        DESCRIPTION
TYPICAL DEPTH TO
 WATER TABLE (ft)
    Floodplain
 2. Purchase-Thick Loess
    Belt

 3. Cumberland-Tennessee
    Rivers Section

 4. Western Coal Fields-Low
    Hills and Valley Areas
  Commerce-Sharkey-
  Robinsville
  Grenada-Calloway-Falaya
  Brandon-Lax-Guin
 Loring-Memphis-Falaya
 5. Western Coal Fields-Hflly Zanesville-Gilpin-Weikert-
    Uplands; Sandstone-     Caneyville
    Shale-Limestone Area of
    the Western Pennyroyal
 6. Western Pennyroyal-      Pembroke-Cumberland-
    Limestone Area          Crider
 7. Knobs
 8. Outer Bluegrass
                           Carmon-Coyler-Captina
 Lowell-Shelbyville-
 Fairmont
9. Hills of the Bluegrass      Eden-Faywood-Nicholson
10. Liner Bluegrass
11. Eastern Pennyroyal
12. Mountains and Eastern
   Coalfields
Maury-Lowell-McAfee
Waynesboro-Baxter-
Garmon-Bedford
Shelocta-Jefferson-Rarden-
Weikert
  level, generally poorly drained
  soils developed from
  Mississippi River sediments

  soils derived from thick loess
  overlying gravel, sand, or clay

  soils developed in thin loess
 Upland soils are generally
 developed on loess overlying
 sandstone and shale.
 Bottomland soils are generally
 poorly drained silt loams or clay
 loams

 Soils developed on sandstone,
 shale, loess, and some
 limestone. Level upland areas
 and bottomlands are generally
 poorly drained.

 Generally well-grained soils
 developed on limestone; karst is
 common

 Soils on Knobs are shallow.
 stony, and poor; soils on
 valleys between knobs are
 generally low in organic matter
 and poorly drained

 Gently rolling plains; soils
 developed on limestones; less
 phosphatic than soils of Inner
 Bluegrass

 Hillslopes of 20-30 percent are
 common; bedrock outcrops at
 surface in many places; soils are
 phosphatic

 gently rolling topography;  soils
 derived from phosphatic
 limestone

 generally well-drained soils
 developed on limestones  and
 shales; karst topography
common

generally moderately- to  well-
drained soils developed on
sandstones and shales
                                                                                             1-2
                                                                   1-2
                                                                   >6
        0-3
                                                               mostly >6
                                                                   >6
                                                                                             >6
                                                                                            >6
                                                                                            >6
                                                                                            >6
                                                                                            >6
        >6

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           Bsmt. & 1st Floor Rn
              % > 4 pCi/L
    61 L
OtolO
11 to 20
21 to 40
41 to 60
61 to 80
Missing Data
or < 5 measurements
                                    100 Miles
               Bsmt. & 1st Floor Rn
           Average Concentration (pCi/L)
            13 ES
     61 L
 0.0 to 1.9
 2.0 to 4.0
 4.1 to 10.0
 10.1 to 11.5
 Missing Data
 or < 5 measurements
Figure 8. Screening indoor radon data from the EPA/State Residential Radon Survey of
Kentucky, 1986-87, for counties with 5 or more measurements.  Data are from 2-7 day charcoal
canister tests. Histograms in map legends show the number of counties in each category. The
number of samples in each county (See Table 1) may not be sufficient to statistically characterize
the radon levels of the counties, but they do suggest general trends. Unequal category intervals
were chosen to provide reference to decision and action levels.

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TABLE 1.  Screening indoor radon data from the EPA/State Residential Radon Survey of
Kentucky conducted during 1986-87. Data represent 2-7 day charcoal canister measurements
from the lowest level of each home tested.
COUNTY
ADAIR
ALLEN
ANDERSON
BALLARD
BARREN
BATH
BELL
BOONE
BOURBON
BOYD
BOYLE
BRACKEN
BREATHrrr
BRECKINRIDGE
BULLITT
BUTLER
CALDWELL
GALLOWAY
CAMPBELL
CARLISLE
CARROLL
CARTER
CASEY
CHRISTIAN
CLARK
CLAY
CLINTON
CRITTENDEN
CUMBERLAND
DAVIESS
EDMONSON
ELLIOTT
ESTILL
FAYETTE
FLEMING
FLOYD
FRANKLIN
FULTON
GALLATIN
GARRARD
GRANT
NO. OF
MEAS.
1
4
2
8
7
7
4
13
10
19
2
4
1
4
11
14
5
8
25
4
1
3
7
16
4
1
3
6
3
20
5
2
4
52
2
5
17
1
1
5
1
MEAN
0.4
0.9
0.9
0.8
1.2
2.7
1.2
1.3
8.3
1.4
1.5
2.8
1.5
1.4
11.5
0.8
1.3
0.9
1.8
0.9
1.5
0.8
1.9
1.5
1.3
4.4
5.0
0.7
8.6
1.0
1.7
2.0
9.0
6.4
4.8
0.6
5.2
0.4
0.6
1.1
0.7
GEOM.
MEAN
0.4
0.6
0.9
0.7
1.1
1.5
0.9
1.1
4.8
0.9
1.1
1.9
1.5
1.0
5.0
0.5
1.1
0.8
1.0
0.8
1.5
0.8
1.5
0.8
1.2
4.4
4.0
0.6
3.6
0.7
1.2
1.9
5.9
4.2
3.6
0.5
3.6
0.4
0.6
0.9
0.7
MEDIAN
0.4
0.9
0.9
0.7
1.1
1.8
0.8
1.0
5.8
1.2
1.5
1.7
1.5
1.3
4.8
0.5
1.3
0.8
0.9
0.9
1.5
0.7
1.8
0.9
1.3
4.4
3.3
0.5
1.5
1.0
0.9
2.0
6.5
4.1
4.8
0.5
5.7
0.4
0.6
0.7
0.7
STD.
DEV.
0.0
0.7
0.0
0.4
0.7
2.8
1.1
0.8
9.2
1.2
1.4
2.9
0.0
1.2
19.0
0.6
0.6
0.3
2.3
0.5
0.0
0.3
1.3
1.4
0.8
0.0
4.2
0.5
12.3
0.7
1.7
0.8
8.7
5.2
4.3
0.3
3.4
0.0
0.0
0.9
0.0
MAXIMUM
0.4
1.8
0.9
1.4
2.5
8.5
2.7
2.8
31.2
4.9
2.5
7.1
1.5
2.9
65.5
1.9
2.0
1.3
9.6
1.5
1.5
1.2
4.2
4.3
2.2
4.4
9.8
1.6
22.8
2.6
4.7
2.6
21.4
20.2
7.8
0.9
10.6
0.4
0.6
2.6
0.7
%>4pCi/L
0
0
0
0
0
14
0
0
60
5
0
25
0
0
55
0
0
0
12
0
0
0
14
6
0
100
33
0
33
0
20
0
75
50
50
0
53
0
0
0
0
	
%>20 pCi/L
0
0
0
0
0
0
0
0
10
0
0
0
0
0
18
0
0
0
0
0
0
0
0
0
0
0
0
0
33
0
0
0
25
2
0
0
0
0
0
0
0

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TABLE 1 (continued). Screening indoor radon data for Kentucky.
  COUNTY
GRAVES
GRAYSON
NO. OF
MEAS.
MEDIAN
    0.6
    1.2
GREEN
GREENUP
HANCOCK
HARDEN
HARLAN
HARRISON
HENDERSON
 JEFFERSON
 JESSAMINE
 KENTON
 KNOTT
 KNOX
 LARUE
 LAUREL
 LAWRENCE
 LETCHER
 LEWIS
 LIVINGSTON
 LOGAN
 MAGOFFIN
 MARION
 MARSHALL
 MASON
 MCCRACKEN
  MCCREARY
  MEADE
  MENIFEE
  MERCER
  METCALFE
  MONROE

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TABLE 1 (continued). Screening indoor radon data for Kentucky.
COUNTY
MONTGOMERY
MORGAN
MUHLENBERG
NELSON
NICHOLAS
OHIO
OLDHAM
OWEN
PENDLETON
PERRY
PIKE
POWELL
PULASKI
ROBERTSON
ROCKCASTLE
ROWAN
RUSSELL
SCOTT
SHELBY
SIMPSON
SPENCER
TAYLOR
TODD
TRIGG
TRIMBLE
UNION
WARREN
WASHINGTON
WAYNE
WEBSTER
WfflTLEY
WOLFE
WOODFORD
NO. OF
MEAS.
5
7
6
13
5
3
2
1
8
4
9
4
8
2
4
3
2
8
6
8
1
4
6
8
1
6
25
3
1
3
6
2
6
MEAN
4.6
1.2
2.2
4.0
1.2
0.8
2.5
0.7
3.5
1.1
1.5
1.4
2.9
0.4
6.1
3.0
0.4
5.5
2.6
1.9
0.5
1.8
1.1
1.1
0.2
0.6
7.6
1.6
1.7
1.3
0.9
0.2
3.1
GEOM.
MEAN
3.7
0.7
0.7
3.0
1.2
0.8
1.8
0.7
1.9
0.9
1.4
1.0
2.0
0.2
1.4
2.9
0.3
2.4
0.9
1.2
0.5
1.6
0.9
0.6
0.2
0.5
4.3
1.3
1.7
1.0
0.8
0.1
1.9
MEDIAN
3.9
0.6
0.8
3.1
1.1
0.9
2.5
0.7
3.0
1.2
1.2
1.1
2.1
0.4
0.7
3.0
0.4
1.6
2.3
1.0
0.5
1.8
1.2
0.9
0.2
0.5
5.4
1.5
1.7
1.0
0.9
0.2
2.1
STD.
DEV.
3.7
1.3
3.3
3.6
0.3
0.3
2.3
0.0
3.1
0.6
0.6
1.1
2.3
0.4
11.1
1.3
0.1
9.6
2.7
2.6
0.0
0.8
0.6
1.1
0.0
0.5
8.0
1.2
0.0
1.0
0.5
0.2
3.3
MAXIMUM
11.1
3.9
8.5
14.8
1.6
1.1
4.1
0.7
8.2
1.6
2.2
2.9
6.5
0.6
22.8
4.3
0.4
29.0
6.5
8.2
0.5
2.7
1.8
3.3
0.2
1.7
31.7
2.9
1.7
2.4
1.8
0.3
9.3
%>4pCi/L
20
0
17
38
0
0
50
0
38
0
0
0
38
0
25
33
0
25
33
13
0
0
0
0
0
0
60
0
0
0
0
0
17
%>20 pCi/L
0
0
0
0
0
0
0
0
0
0
0
0
0
0
25
0
0
13
0
0
0
0
0
0
0
0
8
0
0
0
0
0
0

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       The distribution of indoor radon levels correlates fairly well with the underlying geology in
Kentucky. Elevated indoor radon levels occur in the Inner Bluegrass region and in homes
underlain by the New Albany Shale. Homes in the Jackson Purchase Region have generally low
indoor radon levels. Bullitt and Hart Counties had average screening radon levels greater than
10 pCi/L. The elevated levels in Bullitt County appear to correspond to outcrops of the New
Albany Shale, whereas those in Hart County appear to correspond with outcrops of Ordovician
limestone. Fifty percent or more of the homes tested in Bourbon, Bullitt, Fayette, Franklin, Hart,
and Warren Counties had indoor radon levels exceeding 4 pCi/L. Homes in the Cumberland
Plateau region, which has a generally low radiometric signature (fig. 5), have correspondingly low
average indoor radon levels (fig. 8).

GEOLOGIC RADON POTENTIAL

       A comparison of geology (fig. 2) with surface radioactivity (fig. 5) and screening indoor
radon test data (fig. 8) provides preliminary indications of rock types and geologic features
suspected of producing elevated radon levels. Three primary areas are identified:  (1) areas
underlain by Devonian black shales in the Outer Bluegrass region; (2) areas underlain by the
Ordovician Lexington Limestone, particularly the Tanglewood Member, in the Inner Bluegrass
region; and (3) areas of the Mississippian Plateau underlain by karst limestones or black shales. In
addition, some homes underlain by, or in close proximity to, major faults in the Western Coalfield
and Inner Bluegrass regions (fig. 10) may have locally elevated indoor radon levels due to
localized concentrations of radioactive minerals and higher permeability in fault and fracture zones
(Gundersen, 1989). The black shale and limestone areas in the Mississippian Plateau region have
associated high surface radioactivity, and the Western Coalfield contains scattered radioactivity
anomalies (fig. 5). The arcuate pattern of radioactivity anomalies along the southern edge of the
Outer Bluegrass region corresponds closely to the outcrop pattern of the New Albany Shale. A
group of radiometric anomalies in the vicinity of Warren and Logan counties appears to correspond
to outcrops of the Mississippian Ste. Genevieve and St. Louis Limestones (McDowell and others,
1981). The clastic sedimentary rocks of the Cumberland Plateau region are characterized by
relatively low surface radioactivity and generally have low indoor radon levels.
       The majority of homes in the Jackson Purchase Region have low indoor radon levels,
although the area is underlain in part by loess with an ell signature in the 2.0-3.0 ppm ell range.
The poor correspondence of indoor radon levels with surface radioactivity in this area may be due
to a combination of low soil permeability and seasonal high water tables. Western Kentucky is the
only part of the State in which seasonal high water tables were consistently listed in the SCS soil
surveys as less than 6 ft, and commonly less than 2 ft (fig. 7). In the Mississippian Plateau
Region, locally elevated indoor radon levels are likely in areas with high soil permeability, solution
cavities, or localized concentrations of radioactive minerals in karst regions, and in areas underlain
black shale along the State's southern border. Of particular concern are the Devonian-
Mississippian Chattanooga Shale (equivalent to the New Albany Shale), limestones in the
Mississippian Fort Payne Formation, and the Mississippian Salem, Warsaw, Harrodsburg, St.
Louis, and Ste. Genevieve Limestones in south-central Kentucky.
       Caves produced by limestone solution, which are relatively common in central Kentucky,
are natural concentrators of radon and can be a local source of high radon levels. Radon progeny
levels approaching a maximum of 2.0 working levels (WL), which corresponds to about 400
pCi/L of radon (if radon and its decay products are in 50 percent equilibrium), and averaging about

                                          IV-17    Reprinted from USGS Open-File Report 93-292-D

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0.70 WL, or about 140 pCi/L of radon, have been recorded in Mammoth Gave (Yarborough,
1980). Although these levels are not considered hazardous if the exposure is of short duration,
such as would be experienced by a visitor to the cave, it could be of concern to National Park
Service employees and other persons that spend longer periods of time in the caves. Another
potential hazard is the use of cave air for building air temperature control, as was formerly done at
the Mammoth Cave National Park visitor center.  The cave air, which averages 54°F (Yarborough,
1980), was pumped into the visitor center for cooling, but this process has been discontinued due
to the relatively high radioactivity associated with the cave air.

SUMMARY

       For purposes of assessing radon potential, Kentucky was divided into eight major areas
(fig. 11) and scored with a Radon Index (RI), a measure of radon potential based on geologic,
soil, radioactivity, and housing construction factors, and an associated Confidence Index (CI), a
measure of the relative confidence of the assessment based on the quality and quantity of data used
to make the predictions (Table 2).  For further details on the ranking schemes and the factors used
in the predictions, refer to the introduction chapter of this regional book.
       The Jackson Purchase has a low geologic radon potential (RI=6) with high  a confidence
index (CI=11). River alluvium containing relatively little uranium (although the area displays a
somewhat elevated radiometric signature) and seasonally high water tables appear to be important
controlling factors. The Mississippian Plateau has a moderate (RI=11) radon potential, with high
confidence (CI=10).  Although the RI score for this area falls in the moderate category, it is near
the upper end of the moderate range, primarily due to areas of the Mississippian Plateau underlain
by karst limestones or localized black shales which generate locally high indoor radon levels. The
Eastern Pennyroyal region is underlain by limestones, shales, and siltstones ranging in  age from
Ordovician to Mississippian. This region has a geologic high radon potential (RI=12) with high
confidence (CI=11).  Geologic  units most likely to cause elevated indoor radon in the Eastern
Pennyroyal region include the Devonian-Mississippian Chattanooga Shale (equivalent to the New
Albany Shale), limestones in the Mississippian Fort Payne Formation, and the Mississippian
Salem, Warsaw, Harrodsburg,  St. Louis, and Ste. Genevieve Limestones.  The Western Coalfield
has a moderate geologic radon  potential (RI=9) with high confidence (CI=10). The Inner  ,
Bluegrass region has a high indoor radon potential (RI=13) due to the presence of phosphatic
limestones, particularly the Ordovician Lexington Limestone, that underlie most of the region.
This ranking has a high Confidence Index (CI=11).  The area of the Outer Bluegrass region
underlain primarily by Ordovician limestones has a moderate (RI=11) radon potential with high
confidence (CI=11).  Areas underlain by the Devonian-Mississippian New Albany Shale have the
highest radon potential in the State (RI=14, CI=11). A significant proportion of the homes built on
this black shale unit are likely to have elevated indoor radon levels. The Cumberland Plateau has a
moderate (RI=9) radon potential, but, due to the sparse nature of the existing indoor radon data and
the variable geology, the Confidence Index for this ranking falls in the moderate category (CI=8).
       This is a generalized assessment of the State's geologic radon potential and there is no
substitute for having a home tested. The conclusions about radon potential presented in this report
cannot be applied to individual homes or building sites. Indoor radon levels, both high and low,
can be quite localized, and within any radon potential area there will likely be areas with higher or
lower radon potential than assigned to the area as a whole. Any local decisions about radon should
not be made without consulting all available local data. For additional information on radon and
how to test,  contact your State radon program or EPA regional office. More detailed information
on state or local geology may be obtained from the State geological survey.  Addresses and phone
numbers for these agencies are listed in chapter 1 of this booklet.

                                           IV-19   Reprinted from USGS Open-File Report 93-292-D

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                                                                                                         2

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TABLE 2. Radon Index (RI) and Confidence Index (CI). scores for geologic radon potential
areas of Kentucky. Refer to figure 11 for locations of areas.
FACTOR
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
TOTAL
RANKING
FACTOR
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
TOTAL
Jackson
Purchase
RI CI
1 3
2 3
1 3
1 2
1
0
6 11
LOW HIGH
Outer
Bluegrass
RI CI
2 3
2 3
3 3
1 2
3
0 --
11 11
Mississippian
Plateau
RI CI
2 3
2 3
3 2
2 2
2
0
11 10
MOD HIGH
New Albany
Shale
RI CI
3 3
3 3
3 3
2 2
3
0
14 11
Inner
Bluegrass
RI CI
3 3
2 3
3 3
2 2
3 --
0
13 11
HIGH HIGH
Cumberland
Plateau
RI CI
2 1
2 3
2 2
2 2
1 -
0
9 8
Western
Coalfield
RI CI
1 3
2 3
2 2
2 2 .
2
0
9 10
MOD HIGH
Eastern
Pennyroyal
RI CI
2 3
2 3
3 3
2 2
, 3
0
12 11
        RANKING  MOD  HIGH
HIGH  HIGH
MOD  MOD
HIGH  HIGH
RADON INDEX SCORING:

          Radon potential category
          LOW                        3-8 points
          MODERATE/VARIABLE      9-11 points
          HIGH                      > 11 points

                           Possible range of points = 3 to 17

 CONFIDENCE INDEX SCORING:
                 Probable screening indoor
   Point range        radon average for area
          LOW CONFIDENCE
          MODERATE CONFIDENCE
          HIGH CONFIDENCE
         4-6 points
         7-9 points
         10 -12 points
                           Possible range of points = 4 to 12
                        < 2 pCi/L
                        2-4pCi/L
                        >4pCi/L
                                      IV-21    Reprinted from USGS Open-File Report 93-292-D

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                         REFERENCES CITED IN THIS REPORT  .
         AND GENERAL REFERENCES PERTAINING TO RADON IN KENTUCKY

. Bladen, W.A., 1977, Geology and tectonics, in Karan, P.P., and Mather, Cotton, eds., Atlas of
        Kentucky: Lexington, Ky, the University Press of Kentucky, p. 97-99.

 Bladen, W.A., and Bailey. H.H., 1977, Land use and physical characteristics, in Karan, P.P.,
        and Mather, Cotton, eds., Atlas of Kentucky: Lexington, Ky, the University Press of
        Kentucky, p. 109-114.

 Cressman, E.R., 1973, Lithostratigraphy and depositional environments of the Lexington
        Limestone (Ordovician) of central Kentucky: U.S. Geological Survey Professional Paper
        768, 61 p.

 Duval, J.S., Jones, W.J., Riggle, F.R., and Pitkin, J.A., 1989, Equivalent uranium map of
        conterminous United States: U.S. Geological Survey Open-File Report 89-478, 10 p.

 Geodata International, 1980, Aerial radiometric and magnetic survey, Winchester National
        Topographic Map, Kentucky: U.S. Department of Energy, National Uranium Resources
        Evaluation Report GJBX-23(80), 73 p.

 Gundersen, L.C.S., 1989, Anomalously high radon in shear zones, in Osborne, M.C., and
        Harrison, J., symposium cochairs, Proceedings of the 1988 EPA Symposium on Radon
        and Radon Reduction Technology, volume 1, oral papers: U.S. Environmental Protection
        Agency report EPA/600/9-89/006a, p. 5-27 to 5-44.

 Gustavson, J.B., 1982, Dyersburg Quadrangle, Illinois, Kentucky, Missouri, and Tennessee:
        U.S. Department of Energy National Uranium Resource Evaluation Report PGJ/F-
        103(82), 30 p.

 Karan, P.P., and Mather, Cotton, eds., 1977, Atlas of Kentucky: Lexington, Ky, the University
        Press of Kentucky,  188 p.

 Mather, Cotton, 1977, The land of Kentucky, in Karan, P.P., and Mather, Cotton, eds., Atlas of
        Kentucky: Lexington, Ky, the University Press of Kentucky, p. 8-11.

 McDowell, R.C., ed., 1986, The geology of Kentucky—a text to accompany the geologic map of
        Kentucky: U.S. Geological Survey Professional Paper 1151-H, 76 p.

 McDowell, R.C., Grabowski, G.J., Jr., and Moore, S.L, 1981, Geologic map of Kentucky:
        U.S. Geological Survey, scale 1:250,000, 4 sheets.

 McGrain, Preston, 1983, The geologic story of Kentucky: Kentucky Geological Survey Series
        11, Special Publication 8,74 p.

 Newell, W.L., 1986, Physiography, in McDoweU, R.C., ed., The geology of Kentucky—a text
        to accompany the geologic map of Kentucky: U.S. Geological Survey Professional Paper
        1151-H, p. 64-68.

                                          IV-22     Reprinted from USGS Open-File Report 93-292-D

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Peake, R.T., and Schumann, R.R., 1991, Regional radon characterizations, in Guhdersen,
      L.C.S., and Wanty, R.B., eds., Field studies of radon in rocks, soils, and water: U.S.
      Geological Survey Bulletin 1971, p. 163-175.

Phillips, P.D.,  1977, Housing characteristics, in Karan, P.P., and Mather, Cotton, eds., Atlas of
      Kentucky: Lexington, Ky, the University Press of Kentucky, p. 43-45.

Provo, L.J., Kepferle, R.C., and Potter, P.E., 1977, Three Lick Bed: Useful stratigraphic marker
      in Upper Devonian shale in eastern Kentucky and adjacent areas of Ohio, West Virginia,
      and Tennessee: U.S. Department of Commerce, National Technical Information Service
      Report ERDA-MERC/CR-77-2,56 p.

Steele, S.R., 1980, Exploratory radon survey of the northern Mississippi Embayment; indications
      of buried faults: Eos, Transactions, American Geophysical Union, v. 61, p. 1194-1195.

Steele, S.R., 1981, Radon and hydrologic anomalies on Rough Creek Fault; possible precursors
      to Maysville, Ky. quake:  Eos, Transactions, American Geophysical Union, v. 62,
      p.  1033.

Steele, S.R., 1981, Radon and hydrologic anomalies on the Rough Creek Fault; possible
      precursors to the M5.1 eastern Kentucky earthquake, 1980:  Geophysical Research Letters,
       v.  8, p. 465-468.  -

Webster, J.W. and Crawford, N.C., 1988, The effects of caves on residential radon levels;
       Bowling Green, Warren County, Kentucky: Geological Society of America, Abstracts
       with Programs, v. 20, p. 322.

Winsor, J.H., and Bailey, H.H., 1964, A key to Kentucky soils: Lexington, Ky., University of
       Kentucky, Agricultural Experimental Station Miscellaneous Report 204,35 p.

Yarborough, K.A., 1980, Radon- and thoron-produced radiation in National Park Service caves,
       in Gessell, T.F., and Lowder, W.M., ed., Natural radiation environment IE, Vol. 2:
       Proceedings of International symposium on the natural radiation environment, Houston,
       TX, United States April 23-28,1978, DOE Symposium Series 2, p. 1371-1395.
                                          IV-23    Reprinted from USGS Open-File Report 93-292-D

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                             EPA's Map of Radon Zones
       The USGS' Geologic Radon Province Map is the technical foundation for EPA's Map
of Radon Zones.  The Geologic Radon Province Map defines the radon potential for
approximately 360 geologic provinces.  EPA has adapted this informatiorvto fit a county
boundary map in  order to produce the Map of Radon Zones.
       The Map of Radon Zones is based on the same range of predicted screening levels of
indoor radon as USGS' Geologic Radon Province Map. EPA defines the three zones as
follows:  Zone One areas have an average  predicted indoor radon screening potential greater
than 4 pCi/L.  Zone Two areas are predicted to have an average indoor radon screening
potential between 2 pCi/L and 4 pCi/L. Zone Three areas are predicted to have an average
indoor radon screening potential less than 2 pCi/L.
       Since the geologic province boundaries cross state and county boundaries,  a strict
translation of counties from the Geologic Radon Province Map  to the Map of Radon  Zones
was not possible.  For counties that have variable radon potential (i.e., are located in  two  or
more provinces of different rankings), the counties were assigned to a zone based on  the
predicted radon potential of the province in which most of its area lies.  (See Part I for more
details.)

KENTUCKY MAP OF RADON ZONES

       The Kentucky Map of Radon Zones and its supporting documentation (Part IV of  this
report) have received extensive  review by Kentucky geologists and radon program experts.
The map for Kentucky generally reflects current State  knowledge about  radon for its  counties.
Some States have been able to conduct radon investigations in areas smaller than geologic
provinces and counties, so it is important to consult locally available data.
       Three county designations do not strictly follow the methodology for adapting the
geologic provinces to county boundaries.  EPA, and the Kentucky Department of Health
Services have decided to designate Hart, Pulaski and Warren as Zone 1.  Although these areas
are rated as  having a moderate radon potential on the whole, areas of variability and  high
radon potential are known to exist in these counties. Some of Kentucky's highest indoor
radon measurements have come from homes in these counties.   Although the information
provided in Part IV of this report — the State chapter entitled "Preliminary Geologic  Radon
Potential Assessment of Kentucky" — may appear to be quite specific, it cannot be applied to
determine the radon levels of a  neighborhood, housing tract, individual house, etc.  THE
ONLY WAY TO DETERMINE IF A HOUSE HAS ELEVATED INDOOR RADON  IS
TO TEST.  Contact the Region 4 EPA office or the Kentucky program  for information on
testing and fixing homes.  Telephone numbers and addresses can be found in Part II  of this
report.
                                          V-l

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