United States
Environmental Protection
Air and Radiation
September 1993
EPA's Map of Radon Zones
                                         Printed on Recycled Paper

      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 C.S. Gundersen, R. Randall Schumann, James Otton, Douglas
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.

          I. 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.


       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 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, USGS' 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.

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, and 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
       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





 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.

Figure 3
                Geologic Radon Potential  Provinces for  Nebraska
         Lincoln County
Figure 4
         NEBRASKA -  EPA  Map  of Radon  Zones
         Liacoln  Co is at y
          Zeae 1
                  Zoae 2
                           Zone 3

       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 a--°rages 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 million 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.

       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
designations.  Ir. a few cases, States have requested changes in county zon^ 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 booklets.
       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.
       This document is intended to be a "national overview" of the Map of Radon Zones
project. As previously stated, state-specific booklets that detail the radon potential assessment
for the U.S. have been developed.  EPA strongly recommends that these booklets be
consulted prior to using the Map  of Radon Zones.  The state-specific booklets can be obtained
from the state radon programs that  are listed in Appendix C of this document.

                      Linda C.S. Gundersen and R. Randall Schumann
                                  U.S. Geological Survey
                                    Sharon W. White
                           U.S. Environmental Protection Agency


    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). Copies of the state booklets can be obtained from the
state radon programs  that are listed in Appendix C of this document.
    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

                                           II-1     Reprinted from USGS Open-File Report 93-292

be used to estimate or predict the indoor radon concentrations of individual homes or housing
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
state, 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 (!!:Rn) is produced from the radioactive decay of radium (226Ra), which is, in turn,
a product of the decay  of uranium (**U) (fig.  1).  The half-life of 222Rn is 3.825 days. Other
Isotopes of radon occur naturally, but, with the exception of thoron (220Rn), 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

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

                    E  e
                   .5  S
                    CD —
                   .-  O
                   PL. oo

rismatic structures form in soils with high clay contents.  In soils with shrink-swell clays, air
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

                                           II-4     Reprinted from USGS Open-File Report 93-292

 phenomenon involves temperature/pressure-driven flow of radon-laden air from subsurface
 solution cavities in the carbonate rock in!o 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 (Gam—age 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 winter, 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).


    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.


    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.


    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-

                                           II-5     Reprinted from USGS Open-File Report 93-292

carbonaceous shales and siltstones, certain kinds of clays, silica-poor metamorphic and
igneous rocks, and basalts.  Exceptions exist within these general lithologic groups because of
the occurrence of localized uranium deposits, commonly of the hydrothermal type in
crystalline r  ks 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,


    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 (214Bi), 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
                                           II-6     Reprinted from USGS Open-File Report 93-292

                      2  K If  (1  HUE)
                      5  JH  (3  HUES)
                      2  fc 5  Kli
                      10  KU  (6 HUES)
                      5  i 10 IV.
                      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.

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).
    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 'he 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 surveys prepared by the U.S. Soil Conservation Service (SCS) provide data on  soil
characteristics, including soil-cover thickness, grain-size distribution, permeability, shrmk-
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, shnnk-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

                                            II-8     Reprinted from USGS Open-File Report 93-292

distribution of technical soil types is the "Soils" sheet of the National Atlas (U.S. Department
of Agriculture, 1987).
    Soil permeability is commonly expressed in SCS soil surveys in terms of the speed, in
inches per hour r:i/hr), at which water soaks into the soil, as measured in 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 listed 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 soils 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 smectitic (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 provide
important information for regional radon assessments.


    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
                                           II-9      Reprinted from USGS Open-File Report 93-292














quality and design of a state or other independent survey are discussed and referenced where
the data are used.
    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 indoor radon  data sets other than the State/EPA Residential
Radon Survey are discussed in the individual State  chapters.


    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 ^valuations 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

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

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

INDOOR RADON (average)

< 1.5 ppm eU
mostly slab
2 - 4 pCi/L
1.5 - 2.5 ppm eU
> 2.5 ppm eU
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
                     ^ntial category
                                         Point ranee
                                   Probable average screening
                                    indoor radon for area
                                         3-8 points
                                        9-11 points
                                        12-17 points
                                         2 - 4 pCi/L
                      POSSIBLE RANGE OF POINTS = 3 to 17
                                      INCREASING CONFIDENCE

sparse/no data
questionable/no data
questionable/no data
fair coverage/quality
glacial cover
good coverage/quality
no glacial cover
proven geol. model
reliable, abundant
                                      4-6  points
                                      7-9  points
                                     10 -12 points
                       POSSIBLE RANGE OF POINTS = 4 to 12
                                       11-12     Reprinted from USGS Open-File Report 93-292

 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
 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 pC;n<, 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 United States 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,
    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
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

                                          11-13      Reprinted from USGS Open-File Report 93-292

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
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

                                           II-14    Reprinted from USGS Open-File Report 93-292

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 r~ 4;.oactivity data are available for all but a few areas of the con+;nental 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 ell, 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
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 levels to 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.
                                            11-15     Reprinted from USGS Open-File Report 93-292

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Deffeyes, K.S., and MacGregor, I.D., 1980, World uranium resources: Scientific American,
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Durrance, E.M., 1986, Radioactivity in geology: Principles and applications: New York, N.Y.,
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Duval, J.S., Reimer, G.M., Schumann, R.R., Owen, D.E., and Otton, J.K., 1990, Soil-gas
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Dziuban, J.A., Clifford, M.A., White, S.B., Bergstein, J.W., and Alexander, B.V., 1990,
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Gundersen, L.C.S, Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988b, Map showing radon
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                                          H-17     Reprinted from USGS Open-File Report 93-292

Henry, Mitchell E., Kaeding, Margret E., and Monteverde, Donald, 1991, Radon in soil gas and
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Klusman, R. W., and Jaacks, J. A., 1987, Environmental influences upon mercury, radon, and
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Kovach, E.M., 1945, Meteorological influences upon the radon content of soil gas:  Transactions,
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Kunz, C., Laymon, C.A., and Parker, C., 1989, Gravelly  soils and indoor radon, in Osborne,
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Muessig, K., and Bell, C., 1988, Use of airborne radiometric data to direct testing for elevated
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Ronca-Battista, M., Moon, M., Bergsten, J., White, S.B., Holt, N., and Alexander, B., 1988,
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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/600/9-9 l/026b, p. 6-23-6-36.
                                          II-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, Tenn., 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 JH, 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.
                                          II-19      Reprinted from USGS Open-File Report 93-292

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

Era or


                                    APPENDIX B
                               GLOSSARY OF TERMS
Units 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 of 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, filling 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)
radon tests.

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

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

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"

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"
                                           11-22      Reprinted from USGS O^en-File Report 93-292

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

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
                                          11-23     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 truce main classes into which rocks are divided, the others being sedjuaentary and
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.
Phyllite, 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
soil. 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, phosphatic, phosphorite Any rock or sediment containing a significant amount
of phosphate minerals, i.e., minerals containing PO4.
                                           11-24      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 adj acent 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

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

shale A fine-grained sedimentary rock formed from solidification (lithification) 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
                                           11-25      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

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.
                                           11-26     Reprinted from USGS Open-File Report 93-292

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

EPA Region 2
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
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	...A
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
       Reprinted from USGS Open-File Report 93-292


                                 STATE  RADON CONTACTS
                                             May, 1993
James McNees
Division of Radiation Control
Alabama Department of Public Health
State Office Building
Montgomery, AL 36130
1-800-582-1866 in state

Charles Tedford
Department of Health and Social
P.O. Box 110613
Juneau,AK 99811-0613
1-800-478-4845 in state

John Stewart
Arizona Radiation Regulatory Agency
4814 South 40th St.
Phoenix, AZ 85040
(602) 255-4845
Lee Gershner
Division of Radiation Control
Department of Health
4815 Markham Street, Slot 30
Little Rock, AR 72205-3867
(501) 661-2301
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
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 Program
            Connecticut Department of Health
            150 Washington Street
            Hartford, CT 061064474
            (203) 566-3122

   Delaware Marai G. Rejai
            Office of Radiation Control
            Division of Public Health
            P.O. Box 637
            Dover, DE  19903
            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
            1-800-543-8279 in state

    Georgia Richard Schreiber
            Georgia Department of Human
            878 Peachtree St., Room 100
            Atlanta, GA 30309
            (404) 894-6644
            1-800-745-0037 in state

     Hawaii Russell Takata
            Environmental Health Services
            591 Ala Moana Boulevard
            Honolulu, ffl 96813-2498
            (808) 5864700
                                           Reprinted from USGS Open-File Report 93-292

               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. Hater
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
109 SW 9th Street
6th Floor Mills Building
Topeka, KS 66612
(913) 296-1561

Jeana Phelps
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  Bob Stilwell
              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
              2500 Broening Highway
              Baltimore, MD 21224
              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
                                                11-29      Reprinted from USGS Open-File Report 93-292

Mississippi     Silas Anderson
               Division of Radiological Health
               Department of Health
               3150 Lawson Street
               P.O. Box 1700
               Jackson, MS 39215-1700
               (601) 354-6657
               1-800-626-7739 in state

Missouri       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 Al 13
               Helena, MT 59620
               (406) 444-3671
Nebraska       Joseph Milone
               Division of Radiological Health
               Nebraska Department of Health
               301 Centennial Mall, South
               P.O. Box 95007
               Lincoln, NE 68509
               1-800-334-9491 In State

Nevada         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
   New Jersey Tonalee Carlson Key
              Division of Environmental Quality
              Department of Environmental
              Trenton, NJ 08625-0145
              (609) 987-6369
              1-800-648-0394 in state

  New Mexico William M. Floyd
              Radiation Licensing and Registration
              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
              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

         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
        Reprinted from USGS O^en-File Report 93-292

Puerto Rico
Rhode Island
South Carolina
Gene Smith
Radiation Protection Division
Oklahoma State Department of
P.O. Box 53551
Oklahoma City, OK 73152
George Toombs
Department of Human Resources
Health Division
1400 SW 5th Avenue
Portland, OR 97201
Michael Pyles
Pennsylvania Department of
  Environmental Resources
Bureau of Radiation Protection
P.O. Box 2063
Harrisburg, PA 17120
1-800-23-RADON In State

David Saldana
Radiological Health Division
G.P.O. Call Box 70184
Rio Piedras, Puerto Rico 00936
(809) 767-3563
Edmund Arcand
Division of Occupational Health and
Department of Health
205 Cannon Building
Davis Street
Providence, RI02908
(401) 277-2438
               Bureau of Radiological Health
               Department of Health and
                 Environmental Control
               2600 Bull Street
               Columbia, SC 29201
South Dakota  Mike Pochop
             Division of Environment Regulation
             Department of Water and Natural
             Joe Foss Building, Room 217
             523 E.Capitol
             Pierre, SD 57501-3181

   Tennessee  Susie  Shimek
             Division of Air Pollution Control
             Bureau of the Environment
             Department of Environment and
             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

         2DJ Paul demons
             Occupational and Radiological Health
             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
                                           Reprinted from USGS Open-File Report 93-292

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

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

West Virginia    Beanie 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
                P.O. Box 309
                Madison, WI53701-0309
                (608) 267-4796
                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
Reprinted from USGS Open-File Report 93-292

Kentucky       Donald C. Haney
               Kentucky Geological Survey
               University of Kentucky
               228 Mining & Mineral Resources
                 *. oilding
               Lexington, KY 40506-0107

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) 368-2100

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

      Nebraska  Perry B. Wigley
               Nebraska Conservation & Survey
               113 Nebraska Hall
               University of Nebraska
               Lincoln, NE 68588-0517
               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

   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
                                                IE-34      Reprinted from USGS Open-File Report 93-292

 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 Dept. 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
               Norman, OK 73019-0628
               (405) 325-3031

Oregon         Donald A. Hull
               Dept. of Geology & Mineral Indust.
               Suite 965
               800 NE Oregon St. #28
               Portland, OR 97232-2162

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

Puerto Rico     Ram6n M. Alonso
               Puerto Rico Geological Survey
               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, RI 02881
               (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

         Utah M. Lee Allison
              Utah Geological & Mineral Survey
              2363 S. Foothill Dr.
              Salt Lake City, UT 84109-1491
      Vermont  Diane L. Conrad
               Vermont Division of Geology and
                 Mineral Resources
               103 South Main St.
               Waterbury.VT 05671
               Stanley S. Johnson
               Virginia Division of Mineral
               P.O. Box 3667
               Charlottesville, VA 22903
   Washington  Raymond Lasmanis
               Washington Division of Geology &
                 Earth Resources
               Department of Natural Resources
               P.O. Box 47007
               Olympia, Washington 98504-7007
               (206) 902-1450
                                                11-35      Reprinted from USGS Open-File Report 93-292

  West Virginia  Lairy D. Woodfoik
               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

Wyoming      Gary B. Glass
               Geological Survey of Wyoming
               University of Wyoming
               Box 3008, University Station
               Laramie, WY 82071-3008
               (307) 766-2286
                                               11-36       Reprinted from USGS Open-File Report 93-292