United States
Environmental Protection
Agency
Air and Radiation
(6604J)
402-R-93-045
September 1993
&EPA EPA's Map of Radon Zones
MISSOURI
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EPA'S MAP OF RADON ZONES
MISSOURI
RADON DIVISION
OFFICE OF RADIATION AND INDOOR AIR
U.S. ENVIRONMENTAL PROTECTION AGENCY
SEPTEMBER, 1993
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ACKNOWLEDGEMENTS
This document was prepared by the U.S. Environmental Protection Agency's (EPA's)
Office of Radiation and Indoor Air (ORIA) in conjunction with the U.S. Geological Survey
(USGS). Sharon W. White was the EPA project manager. Numerous other people in ORIA
were instrumental in the development of the Map of Radon Zones, including Lisa Ratcliff,
Kirk Maconaughey, R. Thomas Peake, Dave Rowspn, and -Steve Page.
EPA would especially like to acknowledge the outstanding effort of the USGS
radon team Linda Gundersen, Randy Schumann, Jim Otton, Doug Owen, Russell
Dubiel, Kendell Dickinson, and Sandra Szarzi in developing the technical base for the
Map of Radon Zones. .
ORIA would also like to recognize the efforts of all the EPA Regional Offices in
coordinating the reviews with the State programs and the Association of American State
Geologists (AASG) for providing a liaison with the State geological surveys. In addition,
appreciation is expressed to all of the State radon programs and geological surveys for their
technical input and review of the Map of Radon Zones.
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II. THE USGS/EPA RADON POTENTIAL
ASSESSMENTS:INTRODUCTION
TABLE OF CONTENTS
I. OVERVIEW
III. REGION 7 GEOLOGIC RADON POTENTIAL
SUMMARY
V. PRELIMINARY GEOLOGIC RADON POTENTIAL
ASSESSMENT OF MISSOURI
V. EPA'S MAP OF RADON ZONES -- MISSOURI
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OVERVIEW
Sections 307 and 309 of the 1988 Indoor Radon Abatement Act (IRAA) direct EPA to
identify areas of the United States that have the potential to produce elevated levels of radon.
EPA, the U.S. Geological Survey (USGS),.and the Association of American State Geologists
(AASG) have worked closely over the past several years to produce a series of maps and
documents which 'address these directives. The EPA Map of Radon Zones is a compilation of
that work and fulfills the requirements of sections 307 and 309 of IRAA. The Map of Radon .
Zones identifies, on a county-by-county basis, areas of the U.S. that have the highest potential
for elevated indoor radon levels (greater than 4 pCi/L).
The Map of Radon Zones is designed to assist national, State arid local governments
and organizations to target their radon program activities and resources" It is also intended to
help building code officials determine areas that are the highest priority for adopting radon-
resistant building practices. The Map of Radon Zones should not be used to determine if
individual homes in any given area need to be tested for radon. EPA recommends that all
homes be tested for radon, regardless of'geographic location or the zone! designation of
the county in which they are located. '
This document provides background information concerning the development of the ,'
Map of Radon Zones. It explains the purposes of the map, the approach for developing, the
map (including the respective roles of EPA and USGS), the data sources used, the conclusions
and confidence levels developed for the prediction of radon potential, and the review process
that was conducted to finalize this effort. .
BACKGROUND
Radon (Rn222) is a colorless, odorless, radioactive gas. It comes from the natural
decay of uranium that is found in nearly all soils. It typically moves through the ground to
the air above and into homes and other buildings through cracks and openings in the
foundation. Any home, school or workplace may have a radon problem, regardless of
whether it is new or old, well-sealed or drafty, or'with or without a basement. Nearly one out
of every 15 homes in the U.S. is estimated to have elevated annual average levels of indoor
radon.
Radon first gained national attention in early 1984, when extremely high levels of
indoor radon were found in areas of Pennsylvania, New Jersey, and New York, along the
Reading Prong-physiographic province, EPA established a Radon Program in 1985 to assist
States and homeowners in reducing their risk of lung cancer from indoor radon.
. Since 1985, EPA and USGS have been working together to continually increase .our
understanding of radon sources and the migration dynamics that cause elevated indoor radon
levels! Early efforts resulted in the 1987 map entitled "Areas^with Potentially High Radon
Levels." This map was based on limited geologic information only because few indoor radon
measurements were available at the time. The development of EPA's Map of Radon Zones
and its technical foundation, 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.
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Purpose of the Map of Radon Zones ,
EPA's Map of Radon Zones (Figure 1) assigns each of the 3141 counties in the
United States to one of three zones: '
o Zone 1 counties have a predicted average indoor screening level > than
4 pCi/L
»
o Zone 2 counties have a predicted average screening level > 2 pCi/L and
< 4 pCi/L
o Zone 3 counties have a predicted average screening level < 2 pCi/L
The Zone designations were determined by assessing five factors that are known to. be
important indicators of radon potential: indoor radon measurements, geology, aerial
radioactivity, soil parameters, 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
Radon. ' "
EPA believes that States, local governments and other organizations can achieve
optimal risk reductions by targeting resources and program activities to high radon potential
areas. Emphasizing targeted approaches (technical assistance, information and outreach
efforts, promotion of real estate mandates and policies and building codes, etc.) in such areas
addresses the greatest potential risks first.
EPA also believes that the use of passive radon control systems in the construction of
new homes in Zone 1 counties, and the activation of those systems if necessitated by follow-
up testing, is a cost effective approach to achieving significant radon risk reduction.
The Map of Radon Zones and its supporting documentation establish no regulatory
requirements. Use of this map by State or local radon programs and building code officials is
voluntary. The information presented on the Map of Radon Zones and in the supporting
documentation is not applicable to radon in water.
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Development of the Map of Radon Zones
The technical foundation for the Map of Radon Zones is the USGS Geologic Radon
Province Map. In order to examine the radon potential for the United States, the USGS
began by identifying approximately 360 separate geologic provinces for,the U.S. The
provinces are shown on the USGS Geologic Radon Province Map (Figure 2). Each of the
geologic provinces was evaluated by examining the available data for that area: indoor radon
measurements, geology, aerial radioactivity, soil parameters, and foundation types. As stated
previously, these five factors are considered to be of basic importance in assessing radon
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potential and some data are available for each of these factors in-every geologic province. The
province boundaries do not coincide with political borders (county and state) but define areas
of general radon potential. The five factors were assigned numerical values based on an
assessment of their respective contribution to radon potential, and a confidence level was
assigned to each contributing -variable. The approach used by USGS to estimate the radon
potential for each province is described in Part II of this document.
EPA subsequently developed the Map of Radon Zones by extrapolating from the
province level to the county level so that all counties in the U.S. were assigned to one of
three radon, zones" EPA assigned each county to a given zone based on its provincial radon
potential. For example, if a county is located within a geologic province that has a predicted
average screening level greater than 4 pCi/L, it was assigned to Zone 1. Likewise, counties
located in provinces with predicted average screening levels > 2 pCi/L and <. 4 pCi/L^ and
less than 2 pCi/L, were assigned to Zones 2 and 3, respectively. '-,.
, If the boundaries of a county fall in more than one geologic province, the county was
assigned to a zone based on the predicted radon potential of the province in which most of
the area lies. For example, if three different provinces cross'through a given county, the
county was assigned to the zone representing the radon potential of the province containing
most of the county's land area. (In this case, it is not technically correct to say that the
predicted average screening level applies to the entire county since the county falls in
multiple provinces with differing radon potentials.) .
Figures 3 and 4 demonstrate an example of how EPA extrapolated the county zone
designations for Nebraska from the USGS geologic province map for the State. As figure 3
shows, USGS has identified 5 geologic provinces for Nebraska. Most of the counties are
extrapolated "straight" from their corresponding provinces, but there are counties "partitioned".
by several provinces for example, Lincoln County. Although Lincoln county falls in
multiple provinces, it was assigned to Zone 3 because most of its area falls-in the province .
with the lowest radon potential.
It is important to note that EPA's extrapolation from the province level to the
county level may mask significant "highs" and "lows" within specific counties. In other
words, within-county variations in radon potential are not shown on the Map of Radon
Zones. EPA recommends that users who may need to address specific within-county
variations in radon potential (e.g., local government officials considering the
implementation of radon-resistant construction codes) consult USGS' Geologic Radon
Province Map and the State chapters provided with this map for more detailed
information, as well as any locally available data.
Map Validation
. The Map of Radon Zones is intended to represent a preliminary assessment of radon
potential for the entire United States. The factors that are used in this effort indoor radon
data, geology, aerial radioactivity, soils, and foundation type ~ are basic indicators for radon
potential. It is important to note, however, that the map's county zone designations are not
"statistically valid" predictions due to the nature of the data available for these 5 factprs at the
county level. In order to validate the map in light of this lack of statistical confidence, EPA
conducted a number of analyses. These analyses have helped EPA to identify the best
situations in which to apply the map, and its limitations.
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Figure 3
Geologic Radon Potentia 1 Provinces for Nebraska
Lincoln County
Eifl Moderate Low
Figure 4
NEBRASKA - EPA Map of Radon Zones
Lincoln County
Zoae 1 Zone 2 Zone 3
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One such analysis involved comparing county zone designations to, indoor radon
measurements from the State/EPA Residential Radon Surveys (SRRS). Screening averages
for counties with at least 100 measurements were compared to the counties' predicted radon
potential as indicated by the Map of Radon Zones. EPA found that 72% of the county
screening averages were correctly reflected by the appropriate zone designations on the Map.
In all other cases, they only differed by 1 zone. .
Another accuracy analysis used the.annual average data from the National Residential
Radon Survey ."(NRRS). The NRRS indicated that approximately 6 million homes in the
United States hav£ 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 material's for their geologic
content and consistency. .."*-, ' - .
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In addition to each State geologist providing technical comments, the State radon
offices were asked to comment on their respective States' radon potential evaluations. In
particular, the States were asked to evaluate the data used to assign their counties to specific
zones. EPA and USGS worked with the States to resolve any issues concerning county zone
designations. In a few cases, States have requested changes in county zone designations. The,
requests were based on additional data from the State on geology, indoor radon
measurements, population, etc. Upon reviewing the data submitted by the States, EPA did
make some, changes in zone designations. These changes, which do not strictly follow the .
methodology outlined in this document, are discussed in the respective State chapters.
EPA encourages the States and counties to conduct further research and data collection
efforts to refine the Map of Radon Zones. EPA would like to be kept informed of any
changes the States, counties, or others make to the maps. Updates and revisions will be
handled in a similar fashion to the way the map was developed. States should notify EPA of
any proposed changes by forwarding the changes through the Regional EPA offices that are
listed in Part II. Depending on the amount of new information that is presented, EPA will
consider updating this map periodically. The State radon programs should initiate proper
notification of the appropriate State officials when the Map of Radon Zones is released and
when revisions or updates are made by the State or EPA.
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THE USGS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
.- .-. ; byt ' " ; - .-
Linda C.S. Gundersen and R. Randall Schumann .
U.S. Geological Survey
and
, ""' Sharon W. White
U.S. Environmental Protection Agency
BACKGROUND
The Indoor Radon Abatement Act of 1988 (15 U.S.C. 2661-2671) directed the U.S.
Environmental Protection Agency (EPA) to identify areas of the; United States that have the
potential to produce harmful levels of indoor radon. These characterizations were to be based
on both geological data and on indoor radon levels in homes and other structures. The EPA
also was directed to develop model standards and techniques for new building construction
that would provide adequate prevention or mitigation of radon entry. "As part of an
Interagency Agreement between the EPA and the U.S. Geological Survey (USGS), the USGS
has prepared radon potential estimates for the United States. This report is one of ten
booklets that document this effort. The purpose and intended use of these reports is to help
identify areas where states can target their radon program resources, to provide guidance in
selecting the most appropriate building code options for areas, and to provide general
information on radon and geology for each state for federal, state,.and municipal officials
dealing with radon issues. These reports are not intended to be used as a substitute for
indoor radon testing, and they cannot and should not be used to estimate or predict the
indoor radon concentrations of individual homes, building sites, or housing tracts. Elevated
levels of indoor radon have been found in every State, and EPA recommends that all homes
be tested for indoor radon.
Booklets detailing the radon potential assessment for the U.S. have been developed for
each State., USGS geologists are the authors of the geologic radon potential booklets. Each
booklet consists of several components, the first being an overview to the mapping project
(Part I), this introduction to the USGS assessment (Part II), including a general discussion of
radon (occurrence, transport, etc.), and details concerning the types of data used. The third
component is a summary chapter outlining the general geology.and geologic radon potential
of the EPA Region .(Part III). The fourth component is an individual chapier 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
chaptergeologic; geographic, population, soils, aerial radioactivity, and indoor radon data by
county. Finally, the booklets contain EPA's map of radon zones for each state and an
accompanying description (Part V).
. Because of constraints on the scales of maps presented in these reports and because the
smallest units used to present the indoor radon data are counties, some generalizations have
been, made in order to estimate the radon potential of each area. Variations in geology, soil
characteristics, climatic factors, homeowner lifestyles, and other factors that influence radon
.concentrations can be quite large within any particular geologic area, so these reports cannot
be used to estimate or predict the indoor radon concentrations of individual homes or housing
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tracts. Within any area of a given geologic radon potential ranking, there are likely to be
areas where the radon potential is lower or higher than that assigned to the area as a whole,
especially in larger areas such as the large counties in some western states.
In each state chapter, references to additional reports related to radon are listed for the
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 GENERATION AND TRANSPORT IN SOILS
Radon (2-Rn) is produced from the radioactive decay of radium (226Ra), which is, in turn,
a product of the decay of uranium (23SU) (fig. 1). ,The half-life of :22Rn 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
prismatic structures form in soils with high clay contents. In soils with shrink-swell clays, air
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and moisture infiltration rates and depth of wetting may be limited when the cracks in the
surface soil layers swell shut. Clay-rich B horizons^ particularly those with massive or platy
structure, can form a capping layer that impedes the escape of soil gas to the surface
(Schumann and others, 1992). However, the shrinkage of clays can act to open or widen
cracks upon drying, thus increasing the soil's permeability to gas flow during drier periods.
Radon transport in soils occurs by two processes: (1) diffusion and (2) flow (Tanner,
1964). Diffusion is the process whereby radon atoms move from areas of higher
concentration to areas of lower concentration in response to a concentration gradient. Flow is
the process by which soil air moves through soil pores in response to differences in pressure
within the soil or between the soil and the atmosphere, carrying the radon atoms along with it.
Diffusion is the dominant radon transport process in soils of low permeability, whereas flow
tends to dominate in highly permeable soils (Sextro and others, 1987). In low-permeability
soils, much of the radon may decay before it is able to enter a building because its transport
rate is reduced. Conversely, highly permeable soils, even those that are relatively low in
radium, such as those derived from some types of glacial deposits, have been associated with
high indoor radon levels in Europe and in the northern United States (Akerblom and others,
1984; Kunz and others, 1989; Sextro and others, 1987). In areas of karst topography formed
in carbonate rock (limestone or dolomite) environments, solution cavities and fissures can
increase soil permeability at depth by providing additional pathways for gas flow.
Not all radium contained in soil grains and grain coatings will result in mobile radon
when the radium decays. Depending on where the radium is distributed in the soil, many of
the radon atoms may remain imbedded in the 'soil grain containing the parent radium atom, or
become imbedded in adjacent soil grains. The portion of radium that releases radon into the
pores and fractures of rocks and soils is called the emanating fraction. When a radium atom
decays to radon, the energy generated is strong enough to send the radon atom a distance of
about 40 nanometers (1 nm = 10'9 meters), or about 2x10'* inchesthis is known as alpha
recoil (Tanner, 1980). Moisture in the soil lessens the chance of a recoiling radon atom
becoming imbedded in an adjacent grain. Because water is more dense than air, a radon atom
will travel a shorter distance in a water-filled pore than in an air-filled pore, thus increasing
the likelihood that the radon atom will remain in the pore space. Intermediate moisture levels
enhance radon emanation but do not significantly affect permeability. However, high
moisture levels can significantly decrease the gas permeability of the soil and impede radon
movement through the soil. -
Concentrations of radon in soils are generally many times higher than those inside of
buildings, ranging from tens of pCi/L to more than 100,000 pCi/L, but typically in the range
of hundreds to low thousands of pCi/L. Soil-gas radon concentrations can vary in response to
variations in climate and weather on hourly, daily, or seasonal time scales. Schumann and
others (1992) and Rose and others (1988) recorded order-of-magnitude variations in soil-gas
radon concentrations between seasons in Colorado and Pennsylvania. The most important
factors appear to be (1) soil moisture conditions, which are controlled in large part by
precipitation; (2) barometric pressure; and (3) temperature. Washington and Rose (1990)
suggest that temperature-controlled partitioning of radon between water and gas in soil pores
also has a significant influence on the amount of mobile radon in soil gas.
Homes in hilly limestone regions of the southern Appalachians were found to have higher
indoor radon concentrations during the summer than in the winter. A suggested cause for this
phenomenon involves temperature/pressure-driven flow of radon-laden air from subsurface
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solution cavities in the carbonate rock into houses. As warm air enters solution cavities that
are higher on the hillslope than the homes, it cools and settles, pushing radon-laden air from
lower in the cave or cavity system into structures on the hillslope (Gammage and others,
1993). In contrast, homes built over caves having t>penings situated below the level of the
home had higher indoor radon levels in the winter, caused by cooler outside air entering thea
cave, driving radon-laden air into cracks and solution cavities in the rock and soil, and
ultimately, into homes (Gammage and others, 1993).
RADON ENTRY INTO BUILDINGS
A driving force (reduced atmospheric pressure in the house relative, to the soil, producing
a pressure gradient) and entry, points must exist for radon to enter a building from the soil.
The negative pressure caused by furnace combustion, ventilation devices, and the stack effect
(the rising and escape of warm air from the upper floors of the building, causing a
temperature and pressure gradient within the structure) during cold winter months are
common driving forces. Cracks and other penetrations through building foundations, sump
holes, and slab-to-foundation wall joints are common entry points.
Radon levels in the basement, are generally higher than those on the main floor or upper
floors of most structures. Homes with basements generally provide more entry points for
radon, commonly have a more pronounced stack effect, and typically have lower air pressure
relative to the surrounding soil than nonbasement homes. The term "nonbasement" applies to,
slab-on-grade or crawl space construction. --'.'"-'-
METHODS AND SOURCES OF DATA
The assessments of radon potential in the booklets that follow this introduction were
made using five main types of data: (1) geologic (lithologic); (2) aerial radiometric; (3) soil
characteristics, including soil moisture, permeability, and drainage characteristics; (4) indoor
radon data; and (5) building architecture (specifically, whether homes in each area are built
slab-on-grade or have a basement or crawl space). These five factors were evaluated and
integrated to produce estimates of radon potential. Field measurements of soil-gas radon or
soil radioactivity were not used except where such data were available in existing, published
reports of local field studies. Where applicable, such field studies are described in the
individual state chapters.
GEOLOGIC DATA ' ' .
The types and distribution of lithologic units and other geologic features in an , ,
assessment area are of primary importance in determining radon potential. Rock types that
are most likely to cause indoor radon problems include carbonaceous black shales, glauconite-
bearing sandstones, certain kinds of fluvial sandstones and fluvial sediments, phosphorites,
chalk, karst-producing carbonate rocks, certain kinds of glacial deposits, bauxite, uranium-rich
granitic rocks, metamorphic rocks of granitic composition, silica-rich volcanic rocks, many
sheared or faulted rocks, some coals, and certain kinds of contact metamorphosed rocks.
Rock types least likely to cause radon problems include marine quartz sands, non-
carbonaceous shales and siltstones, certain kinds of clays, silica-poor metamorphic and
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igneous rocks, and basalts. Exceptions exist within these general lithologic groups because of
the occurrence of localized uranium deposits, commonly of the hydrothermal type in
crystalline rocks or the "roll-front" type in sedimentary rocks. Uranium and radium are
commonly sited in heavy minerals, iron-oxide coatings on rock and soil grains, and organic
materials in soils and sediments. Less common are uranium associated with phosphate and
carbonate complexes in rocks and soils, and uranium minerals.
Although many cases of elevated indoor radon levels can be traced to high radium and
(or) uranium concentrations in parent rocks, some structural features, most notably faults and
shear zones, have been identified as sites of localized uranium concentrations (Deffeyes and
MacGregor, 1980) and have been associated with,some of the highest reported indoor radon
levels (Gundersen, 1991). The two highest known indoor radon occurrences are associated ,
with sheared fault zones in Boyertown, Pennsylvania (Gundersen and others, 1988a; Smith
and others, 1987), and in Clinton, New Jersey (Henry and others, 1991; Muessig and Bell,
1988). .
NURE AERIAL RADIOMETRIC DATA
Aerial radiometric data are used to quantify the radioactivity of rocks and soils.
Equivalent uranium (eU) data provide an estimate of the surficial concentrations of radon
parent materials (uranium, radium) in rocks and soils. Equivalent uranium is calculated from
the counts received by a gamma-ray detector from the 1.76 MeV (mega-electron volts)
emission energy corresponding to bismuth-214 (2HBi), with the assumption that uranium and
its decay products are in secular equilibrium. Equivalent uranium is expressed in units of
parts per million (ppm). Gamma radioactivity also may be expressed in terms of a radium
activity; 3 ppm eU corresponds to approximately 1 picocurie per gram (pCi/g) of radium-226.
Although radon is highly mobile in soil and its concentration is affected by meteorological
conditions (Kovach, 1945; Klusman and Jaacks, 1987; Schery and others, 1984; Schumann
and others, 1992), statistical correlations between average soil-gas radon concentrations and
average eU values for a wide variety of soils have been documented (Gundersen and others,
1988a, 1988b; Schumann and Owen, 1988). Aerial radiometric data can provide an estimate
of radon source strength over a region, but the amount of radon that is able to enter a home
from the soil is dependent on several local factors, including soil structure, grain size
distribution, moisture content, and permeability, as well as type of house construction and its
structural condition. ,
The aerial radiometric data used for these characterizations were collected as part of the
Department of Energy National Uranium Resource Evaluation (NURE) program of the 1970s
and early 1980s. The purpose of the NURE program was to identify and describe areas in the
United States having potential uranium resources (U.S. Department of Energy, 1976). The
NURE aerial radiometric data were collected by aircraft in which a gamma-ray spectrometer
was mounted, flying approximately 122 m (400 ft) above the ground surface. The equivalent
uranium maps presented in the state chapters were generated from reprocessed NURE data in
which smoothing, filtering, recalibrating, and matching of adjacent quadrangle data sets were
performed to compensate for background, altitude, calibration, and other types of errors and
inconsistencies in the original data set (Duval and others, 1989). The data were then gridded
and contoured to produce maps of eU with a pixel size corresponding to approximately 2.5 x
2.5 km (1.6 x 1.6 mi).
II-6 Reprinted from USGS Open-File Report 93-292
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FLIGHT LINE SPACING OF SURE AERIAL SURVEYS
2 KU (I .HI IE)
5 IK (3 HUES)
2 i 5 HI
10 .III; (6 UlLtS)
5 fc 10 KM
NO DATA
Figure 2. Nominal flightline spacings for NURE aerial gamma-ray surveys covering the
contiguous United States (from Duval and others, 1990). Rectangles represent I°x2° quadrangles.
-------
Figure 2 is an index map of NURE 1° x 2° quadrangles showing the flight-line spacing
for each quadrangle. In general, the more closely spaced the flightlines are, the more area
was covered by the aerial gamma survey, and thus, more detail is available in the data set.
For an altitude of 400 ft above the ground surface and with primary flightline spacing
typically between 3 and 6 miles, less than 10 percent of the ground surface of the United
States was actually measured by the airborne gamma-ray detectors (Duval and others, 1989), .
although some areas had better coverage than others due to the differences in flight-line
spacing between areas (fig. 2). This suggests that some localized uranium anomalies may not
have been detected by the aerial surveys, but the good correlations of eU patterns with
geologic outcrop patterns indicate that, at relatively small scales (approximately 1:1,000,000
or smaller) the National eU map (Duval and others, 1989) gives reasonably good estimates of
average surface uranium concentrations and thus can assist in the prediction of radon potential
of rocks and soils, especially when augmented with additional geologic and soil data.
The shallow (20-30 cm) depth of investigation of gamma-ray spectrometers, either
ground-based or airborne (Duval and others, 1971; Durrance, 1986), suggests that gamma-ray
data may sometimes underestimate the radon-source strength in soils in which some of the
radionuclides in the near-surface soil layers have been transported downward through the soil
profile. In such cases the concentration of radioactive minerals in the A horizon would be
lower than in the B horizon, where such minerals are typically concentrated. The
concentration of radionuclides in the C horizon and below may be relatively unaffected by
surface solution processes. Under these conditions the surface gamma-ray signal may indicate
a lower radon source concentration than actually exists in the deeper soil layers, which are
most likely to affect radon levels in structures with basements. The redistribution of
radionuclides in soil profiles is dependent on a combination of climatic, geologic, and
geochemical factors. There is reason to believe that correlations of eU with actual soil
radium and uranium concentrations at a depth relevant to radon entry into structures may be
regionally variable (Duval, 1989; Schumann and Gundersen, 1991). Given sufficient
understanding of the factors cited above, these regional differences may be predictable.-
SOIL SURVEY DATA
Soil surveys prepared by the U.S. Soil Conservation Service (SCS) provide data on soil
characteristics, including soil-cover thickness, grain-size distribution, permeability, shrink-
swell potential, vegetative cover, generalized groundwater characteristics, and land use. The
reports are available in county formats and State summaries. The county reports typically
contain both generalized and detailed maps of soils in the area.
Because of time and map-scale constraints, it was impractical to examine county soil
reports for each county in the United States, so more generalized summaries at appropriate
scales were used where available. For State or regional-scale radon characterizations, soil
maps were compared to geologic maps of the area, and the soil descriptions, shrink-swell
potential, drainage characteristics, depth to seasonal high water table, permeability, and other
relevant characteristics of each soil group noted. Technical soil terms used in soil surveys are
generally complex; however, a good summary of soil engineering terms and the national
distribution of technical soil types is the "Soils" sheet of the National Atlas (U.S. Department
of Agriculture, 1987).
II-8 Reprinted from USGS Open-File Report 93-292
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Soil permeability is commonly expressed in SCS soil surveys in terms of the speed, in
inches per hour (in/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-s'well 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.
- , i
INDOOR RADON DATA
Two major sources of indoor radon data were used. The first and largest source of data is
from the State/EPA Residential Radon Survey (Ronca-Battista and others, 1988; Dziuban and
others, 1990). Forty-two states completed EPA-sponsored indoor radon surveys between 1986
and 1992 (fig. 3). The State/EPA Residential Radon Surveys were designed to be
comprehensive and statistically significant at the state level, and were subjected to high levels.
of quality assurance and control. The surveys collected screening indoor radon measurements,
defined as 1-1 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
s,uch as duplexes, townhouses, or condominiums were included in" some of the surveys if they
met the other criteria and had contact with the ground surface. Participants were selected
randomly from telephone-directory listings. In total, approximately 60,000 homes were tested
in the State/EPA surveys.
The second source of indoor radon data comes from residential surveys that have been
conducted in a specific state or region of the country (e.g. independent state surveys or utility
company surveys). Several states, including Delaware, Florida, Illinois, New Hampshire, New
Jersey, New York, Oregon, and Utah, have conducted their own surveys of indoor radon. The
quality and design of a state or other independent survey are discussed and referenced where
the data are used.
II-9 Reprinted from USGS Open-File Report 93-292
-------
Q
-------
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 spurces 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.
RADON INDEX AND CONFIDENCE INDEX
i
Many of the geologic methods used to evaluate an area for radon potential require
subjective opinions based on the professional judgment 'and experience of the individual
geologist. The evaluations are nevertheless based on established scientific principles that-are
universally applicable to any geographic area.or geologic setting.. This section describes the
methods and conceptual framework used by the U.S. Geological Survey to evaluate areas for
radon potential based on the five factors discussed in the previous sections. The scheme is
divided into two basic parts, a Radon Index (RI), used to rank the general radon potential of
the area, and, the Confidence Index (CI), used to express the level of confidence in the
prediction based on the quantity and quality of the data used to make the determination. This
scheme works best if the areas to be evaluated are delineated by geologically-based
boundaries (geologic provinces) rather than political ones (state/county boundaries) in which
-the geology may vary across the. area. -
Radon Index.- Table 1"presents the Radon Index (RI) matrix. The five factorsindoor
radon data, geology, aerial radioactivity, soil parameters, and house foundation typewere
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 usedj 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) wer,e not considered in scoring the indoor radon factor of the
Radon Index if they were not randomly sampled or could not be statistically combined with
the primary indoor radon data sets. However, these additional radon data sets can provide a
means to further refine correlations between geologic factors and radon potential, so they are
11-11 Reprinted from USGS Open-File Report 93-292
-------
TABLE 1. RADON INDEX MATRIX, "ppm eU" indicates parts per million of equivalent
uranium, as indicated by NURE aerial radiometric data. See text discussion for details.
FACTO&
INDOOR RADON (average)
AERIAL RADIOACTIVITY
GEOLOGY*
SOIL PERMEABILITY
ARCHITECTURE TYPE
INCREASING RADON POTENTIAL ^
POINT VALUE
1
<2pCi/L
<1.5ppmeU- '
negative
low
mostly slab
2
2 - 4 pCi/L
1.5 - 2.5 ppm eU
variable
moderate
mixed
3
>4pCi/L
> 2.5 ppm eU
positive
high
mostly basement
*GEOLOGIC FIELD EVIDENCE (GFE) POINTS: GFE points are assigned in addition to points
for the "Geology" factor for specific, relevant geologic field studies. See text for details.
Geologic evidence supporting:
HIGH radon
MODERATE
LOW
No relevant geologic field studies
+2 points
+1 point
-2 points
0 points
SCORING:
Radon potential category
Probable average screening
Point range indoor radon for area
LOW
MODERATE/VARIABLE
HIGH
3-8 points
9-11 points
12-17 points
<2pCi/L
2-4pCi/L
>4pCi/L
POSSIBLE RANGE OF POINTS = 3 to 17
TABLE 2.
CONFIDENCE INDEX MATRIX
INCREASING CONFIDENCE
FACTOR
INDOOR RADON DATA
AERIAL RADIOACTIVITY
GEOLOGIC DATA
SOIL PERMEABILITY
POINT VALUE
1
sparse/no data
questionable/no data
questionable
questionable/no data
2
fair coverage/quality
glacial cover
variable
variable
3
good coverage/quality
no glacial cover
proven geol. model
reliable, abundant
SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
4-6 points
7-9 points
10 -12 points
POSSIBLE RANGE OF POINTS = 4 to 12
II-12 Reprinted from USGS Open-File Report 93-292
-------
included as supplementary information and are discussed in the individual State chapters.. If
the average screening indoor radon level for an area was less than 2 pCi/L, the indoor radon
factor was assigned 1 point, if it was between 2 and 4 pCi/L, it was scored 2 points, and if
the average screening indoor radon level for an area was greater than 4 pCi/L, the indoor
radon factor was assigned 3 RI points.
Aerial radioactivity data used in this report are from the equivalent uranium map of the
conterminous 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 pprn 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 pprri
(2 points), or greater than 2.5 ppm (3 points). ,
The geology factor is complex and actually incorporates many geologic characteristics. In
the matrix, "positive" and "negative" refer to the presence or absence and distribution of rock
types known to have high uranium contents and to generate elevated radon in soils or indoors.
Examples of "positive" rock types include granites, black shales, phosphatic rocks, and other
rock types,described in the preceding "geologic data" section. Examples of "negative" rock
types include marine quartz sands and some clays. The term "variable" indicates that the.
geology within the region is variable or that the rock types in the area are known or suspected
to generate elevated radon in some areas but not in others due to compositional differences,
climatic effects, localizeddistribution of uranium, or other factors. Geologic information
indicates not only how much uranium is present in the rocks and soils but also gives clues for
predicting general radon emanation and mobility characteristics through additional factors
such as structure (notably the presence of faults or shears) and geochemical characteristics
(for example, a phosphate-rich sandstone.will likely contain more uranium than a sandstone
containing little or no phosphate because the phosphate forms chemical complexes with
uranium). "Negative", "variable", and "positive" geology were assigned 1, 2, and 3 points,
respectively. ;
In cases where additional reinforcing or contradictory geologic evidence is available,
Geologic Field Evidence (GFE) points were added to or subtracted from an area's score
(Table 1). Relevant geologic field studies are important to enhancing our understanding of
how geologic processes affect radon distribution. In some cases, geologic models and
supporting field data reinforced an already strong (high or low) score; in others, they provided
important contradictory data. GFE points were applied for geologically-sound evidence that
supports the prediction (but which may contradict one or more factors) on the basis of known
geologic field studies in the area or in areas with geologic and climatic settings similar
enough that they could be applied with full confidence. For example, areas of the Dakotas,
Minnesota, and Iowa that are covered with Wisconsin-age glacial deposits exhibit a low aerial
radiometric signature and score only one RI point in that category. However, data from
geologic field studies in North Dakota and Minnesota (Schumann and others, 1991) suggest
that eU is a poor predictor of geologic radon potential in this area because radionuclides have
- _ ' 11-13 Reprinted from USGS Open-File Report 93-292
-------
been leached from the upper soil layers but are present and possibly even concentrated in
deeper soil horizons, generating significant soil-gas radon. This positive supporting field
evidence adds two GFE points to the score, which helps to counteract the invalid conclusion
suggested by the radiometric data.. No GFE points are awarded if there are no documented
field studies for the area.
"Soil permeability" refers to several soil characteristics that influence radon concentration
and mobility, including soil type, grain size, structure, soil moisture, drainage, slope, and
permeability. In the matrix, "low" refers to permeabilities less than about 0.6 in/hr; "high"
corresponds to greater than about 6.0 in/hr, in-U.S. Soil Conservation Service (SCS) standard
soil percolation tests. The SCS data are for water permeability, which generally correlates
well with the gas permeability of the soil except when the soil moisture content is very high.
Areas with consistently high water tables were thus considered to have low gas permeability.
"Low, "moderate", and "high" permeability were assigned 1, 2, and 3 points, respectively.
Architecture type refers to whether homes in the area have mostly basements (3 points),
mostly slab-on-grade construction (1 point), or a mixture of the'two. Split-level and crawl
space homes fall into the "mixed" category (2 points). Architecture information is necessary
to properly interpret the indoor radon data and produce geologic radon potential categories
that are consistent with screening indoor radon data.
The overall RI for an area is calculated by adding the individual RI scores for the 5
factors, plus or minus GFE points, if any. The total RI for an area falls in one of three
categorieslow, 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
factorsif 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
11-14 Reprinted from USGS Open-File Report 93-292
-------
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 arid biased
toward population* centers and/or high indoor radon levels). The categories listed in the CI
matrix for indoor radon data ("sparse or no data", "fair coverage or quality", and "good
coverage/quality") indicate the sampling density and statistical robustness of an indoor radon
data set Data from the State/EPA Residential Radon Survey and statistically valid state ,
surveys were typically assigned 3 Confidence Index points unless the data were poorly
distributed or absent in "the area evaluated.
Aerial radioactivity,data are available for all but a few areas of the continental United
States and for part of Alaska. An evaluation of the quality of the radioactivity data was based
on whether there appeared to be a good correlation between the radioactivity and the actua}
amount of uranium or radium available to generate mobile radoh in the rocks and soils of the
area evaluated. In general, the greatest problems with correlations among eU, geology, and
soil-gas or indoor radon levels were associated with glacial deposits (see the discussion in a
previous section) and typically were assigned a 2-point Confidence Index score. Correlations
among eU, geology, and radon were generally sound in unglaciated areas and were usually
assigned 3.CI points. Again, however, radioactivity data in some unglaciated areas may have"
been assigned fewer than 3 points, and in glaciated areas may be assigned only one point, if
the data were considered questionable or if coverage was poor.
To assign Confidence Index scores for the geologic data factor, rock types and geologic
settings for which a physical-chemical, process-based understanding of radon generation and
mobility exists were regarded as having "proven .geologic models" (3 points); a high
confidence could be held for predictions in such areas. Rocks for which the processes are
less .well known or for which data are contradictory were regarded as "variable" (2 points),
and those about which little is known or for which no apparent correlations have been found
were deemed "questionable" (1 point). " , ,
The soil permeability factor was also scored based on quality and amount of data. The
three categories for soil permeability in the Confidence Index-are similar in concept, and
scored similarly,, to those for the geologic data factor. Soil permeability can be roughly
estimated from grain size and drainage class if data from standard, accepted soil percolation
tests are unavailable; however, the reliability of the data would be lower than if percolation
test figures or other measured permeability data are available, because an estimate of this type
does not encompass all the factors that affect soil permeability and thus may be inaccurate in
some instances. Most published soil permeability data are for water; although this is
generally closely related to the air permeability of the soil, there are some instances when it
may provide an incorrect estimate. Examples of areas in which water permeability data may
not accurately reflect air permeability include areas with consistently high levels of soil
moisture, or clay-rich soils, which would have a low water permeability but may have a
.11-15 Reprinted from USGS Open-File Report 93-292
-------
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.
11-16 Reprinted from USGS Open-File Report 93-292
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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 weiather and soil
characteristics on temporal variations in soil-gas radon concentrations, in Gates, A.E., and
Gunderserij L.G.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 Neroy A.V., 1987,
Investigations of soil as a source of indoor radon, in Hopke, P.K., ed., Radon and its
decay products: American Chemical Society Symposium Series 331, p. 10-29.
Sterling, R., Meixel, G., Shen, L., Labs, K., and Bligh, T., 1985, Assessment of the energy
savings potential of building foundations research: Oak Ridge, Term., U.S. Department of
Energy Report ORNL/SUB/84-0024/1. ' - '
Smith, R.C., H, Reilly, M.A., Rose, A.W., Barnes, J.H., and Berkheiser, S.W., Jr., 1987,
Radon: a profound case: Pennsylvania Geology, v. 18, p. 1-7. .
Tanner, A.B., 1964, Radon migration in the ground: a review, in Adams, J.A.S., and Lowder,
W.M., eds., The natural radiation environment: Chicago, HI'., University of Chicago
Press, p. 161-190.
Tanner, A.B., 1980, Radon migration in the ground: a supplementary review, in Gesell, T.F.,
and Lowder, W.M. (eds), Natural radiation environment IH, 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 Adas 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 tof
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
Eonothem
Phanerozoic2
Proierozoic
(EJ
Archean
(A)
Era or
Erathem
«
Cenozoic *
(Cz)
Mesozoic2
(Mi)
Paleozoic
(Pz)
P,0,.£'oie
-------
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
plagioclase.
11-21 Reprinted from USGS Open-FUe 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 ha's more than 40 square miles of surface
exposure and no known bottom.
carbonate A sedimentary rock consisting of the carbonate (COs) compounds of calcium,
magnesium, or iron, e.g. limestone and dolomite.
carbonaceous Said of a rock or sediment that is rich in carbon, is coaly, or contains organic
matter.
charcoal canister A passive radon measurement device consisting of a small container of
granulated activated charcoal that is designed to adsorb radon. Useful for short duration (2-7 days)
measurements only. May be referred to as a "screening" test
chert A hard, extremely dense sedimentary rock consisting dominantly of interlocking crystals of
quartz. Crystals are not visible to the naked eye, giving the rock a milky, dull luster. It may be
white or gray but is commonly colored red, black, yellow, blue, pink, brown, or green.
clastic pertaining to a rock or sediment composed of fragments that are derived from preexisting
rocks or minerals. The most common clastic sedimentary rocks are sandstone and shale.
clay A rock containing clay mineral fragments or material of any composition having a diameter
less than 1/256 mm.
clay mineral One of a complex and loosely defined group of finely crystalline minerals made up
of water, silicate and aluminum (and a wide variety of other elements). They are formed chiefly by
alteration or weathering of primary silicate minerals. Certain clay minerals are noted for their small
size and ability to absorb substantial amounts of water, causing them to swell. The change in size
that occurs as these clays change between dry and wet is referred to as their "shrink-swell"
potential.
concretion A hard, compact mass of mineral matter, normally subspherical but commonly
irregular in shape; formed by precipitation from a water solution about a nucleus or center, such as
a leaf, shell, bone, or fossil, within a sedimentary or fractured rock.
conglomerate A coarse-grained, clastic sedimentary rock composed of rock and mineral
fragments larger than 2 mm, set in a finer-grained matrix of clastic material.
cuesta A hill or ridge with a gentle slope on one side and a steep slope on the other. The
formation of a cuesta is controlled by the different weathering properties and the structural dip of
the rocks forming the hill or ridge.
daughter product A nuclide formed by the disintegration of a radioactive precursor or "parent"
atom.
H-22 Reprinted from USGS Open-FUe 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 rbck. It also contains abundant sodium plagioclase and minor
quartz.
dolomite A carbonate sedimentary rock of which more than 50% consists of the mineral dolomite
(GaMg(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 S aid 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,metamorpMsm.
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
H-23 Reprinted from USGS Open-File Report 93-292
-------
and may be referred to as a "placer deposit." Some heavy minerals are magnetite, garnet, zircon,
monazite, and xenotime.
igneous Said of a rock or mineral that solidified from molten or partly molten rock material. It is
one of the three main classes into which rocks are divided, the others being sedimentary and
metamorphic.
intermontane A term that refers to an area between two mountains or mountain ranges.
intrusion, intrusive The processes of emplacement or injection of molten rock into pre-existing
rock. Also refers to the rock formed by intrusive processes, such as an "intrusive igneous rock".
kame A low mound, knob, hummock, or short irregular ridge formed by a glacial stream at the
margin of a melting glacier; composed of bedded sand and gravel.
karst terrain A type of topography that is formed on limestone, gypsum and other rocks by
dissolution of the rock by water, forming sinkholes and caves.
lignite A brownish-black coal that is intermediate in coalification between peat and
subbituminous coal.
limestone A carbonate sedimentary rock consisting of more than 50% calcium carbonate,
primarily in the form of the mineral calcite
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. f
moraine A mound, ridge, or other distinct accumulation of unsorted, unbedded glacial material,
predominantly till, deposited by the action of glacial ice. i
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.
H-24 , Reprinted from USGS Open-File Report 93-292
-------
physiographic province A region in which all parts are similar in geologic structure and
climate, which has had a uniform geomorphic history, and whose topography or landforms differ
significantly from adjacent regions.
placer deposit See heavy minerals
residual Formed by weathering of a material in place.
residuum Deposit of residual material.
rhydlite An extrusive igneous rock of volcanic origin, compositionally equivalent to granite.
sandstone A clastic sedimentary rock composed of sand-sized rock and mineral material that is
more or less firmly cemented. Sand particles range from 1/16 to 2 mm in size.
schist A strongly foliated crystalline rock, formed by metamorphism, that can be readily split into
thin flakes or slabs. Contains mica; minerals are typically aligned.
screening level Result of an indoor radon test taken with a charcoal canister or similar device,
for a short period of time, usually less than seven days. May indicate the potential for an indoor
radon problem but does not indicate annual exposure to radon.
sediment Deposits of rock and mineral particles or fragments originating from material that is
transported by air, water or ice, or that accumulate by natural chemical precipitation or secretion of
organisms. ,
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 i/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 materiaHnto an underlying
void created by the dissolution of carbonate rock. , . ,
slope An inclined part of the earth's surface.
solution cavity A hole, channel or cave-like cavity formed by dissolution of rock.
stratigraphy The study of rock strata; also refers to the succession of rocks of a particular area.
surficial materials Unconsolidated glacial, wind-, or waterborne deposits occurring on the
earth's surface.
tablelands General term for a broad, elevated region with a nearly level surface of considerable
extent ,
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
environment ,
till Unsorted, generally unconsolidated and unbedded rock and mineral material deposited directly
adjacent to and underneath a glacier, without reworking by meltwater. Size of grains varies greatly
from clay to boulders.
uraniferous Containing uranium, usually more than 2 ppm.
vendor data Used in this report to refer to indoor radon data collected and measured by
commercial vendors of radon measurement devices and/or services.
volcanic Pertaining to the activities, structures, and extrusive rock types of a volcano.
water table The surface forming the boundary between the zone of saturation and the zone of
aeration; the top surface of a body of unconfined groundwater in rock or soil.
weathering The destructive process by which earth and rock materials, on exposure to
atmospheric elements, are changed in color, texture, composition, firmness, or form with little or
no transport of the material.
Bt-26 Reprinted from USGS Open-File Report 93-292
-------
APPENDIX C
EPA REGIONAL OFFICES
EPA Regional Offices
State
EPA Region
EPA Region 1
JFK Federal Building
Boston, MA 02203
(617) 565-4502
EPA Region 2
(2A1R:RAD)
26 Federal Plaza
New York, NY 10278
(212) 264-4110
Region3 (3AH14)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-8326
EPA Region 4
345 Courtland Street, N.E.
Atlanta, GA 30365
(404) 347-3907
EPA Region 5 (5AR26)
77 West Jackson Blvd.
Chicago, IL 60604-3507
(312) 886-6175
EPA Region 6 (6T-AS)
1445 Ross Avenue
Dallas, TX 75202-2733
(214) 655-7224
EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7604
EPA Region 8
(8HWM-RP)
999 18th Street
One Denver Place, Suite 1300
Denver, CO 80202-2413
(303) 293-1713
EPA Region 9 (A-3) ^
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1048
EPA Region 10
1200 Sixth Avenue
Seattle, WA 98101
(202) 442-7660
Alabama..... 4
Alaska............... 10
Arizona... 9
Arkansas... 6
California ...; .-..9
Colorado 8
Connecticut 1
Delaware:........... . . 3
District of Columbia.... 3
Florida.............. k....... .....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 f. 8
Tennessee. 4
Texas...... 6
Utah.....;.... .....:.........8
Vermont 1 -
Virginia .3
Washington..... ... 10
West Virginia...... ...3
Wisconsin 5
Wyoming 8
ff-27 Reprinted from USGS Open-File Report 93-292
-------
STATE RADON CONTACTS
May, 1993
Alabama James McNees
Division of Radiation Control
Alabama Department of Public - ..Jth
State Office Building
' Montgomery, AL 36130
(205)242-5315
1-800-582-1866 in state
Alaska Charles Tedford'
Department of Health and Social
Services
P.O. Box 110613
Juneau,AK 99811-0613
(907)465-3019
1-800-478-4845 in state
Arizona John Stewart
Arizona Radiation Regulatory Agency
4814 South 40th St
Phoenix, AZ 85040
(602)255-4845
Arkansas Lee Gershner
Division of Radiation Control
Department of Health
4815 Markham Street, Slot 30
Little Rock, AR 72205-3867
(501) 661-2301
California J. David Quinton
Department of Health Services
714 P Street, Room 600
Sacramento, CA 94234-7320.
(916) 324-2208
1-800-745-7236 in state
Colorado Linda Martin
Department of Health
4210 East llth Avenue
Denver, CO 80220
(303)692-3057
1-800-846-3986 in state
Connecticut Alan J. Siniscalchi
Radon Program
Connec .icut Department of Health
Services
150 Washington Street
Hartford, CT 06106-4474
(203) 566-3122
Delaware Marai G. Rejai
Office of Radiation Control
Division of Public Health
P.O. Box 637
Dover, DE 19903
(302) 736-3028
1-800-554-4636 In State
District Robert Davis
of Columbia DC Department of Consumer and
Regulatory Affairs ~
614 H Street NW
Room 1014
Washington, DC 20001
(202)727-71068
Florida N. Michael Gilley
Office of Radiation Control
Department of Health and
Rehabilitative Services
1317 Winewood Boulevard
Tallahassee, PL 32399-0700
(904)488-1525
1-800-543-8279 in state
ia Richard Schreiber
Georgia Department of Human
Resources
878 Peachtree St, Room 100
Atlanta, GA 30309
(404)894-6644
1-800-745-0037 in state
Hawaii Russell Takata
Environmental Health Services
Division
591 Ala Moana Boulevard
Honolulu, ffl 96813-2498
(808)5864700
n-28
Reprinted from USGS Open-File Report 93-292
-------
Idaho
Illinois
Indiana
Iowa
Kentucky
PatMcGavarn
Offige of Environmental Health
450 West State Street
Boise, ID 83720
(208)334-6584
1-800-445-8647 in state
Richard Allen
Illinois Department of Nuclear Safety
1301 Outer Park Drive .
Springfield, IL 62704
(217)524-5614
1-800-325-1245 in state
Lorand Magyar
Radiological Health Section
Indiana State Department of Health
1330 West Michigan Street
P.O. Box 1964
Indianapolis, IN 46206
(317)633-8563
1-800-272-9723 In State ,
-- \ ' -
Donald A. Plater
Bureau of Radiological Health
Iowa Department of Public Health
Lucas State Office Building
Des Moines, IA 50319-0075
(515)281-3478
1-800-383-5992 In State
Harold Spiker
Radiation Control Program
Kansas Department of Health and
Environment
109 SW 9th Street '
6th Floor Mills Building
Topeka, KS 66612
(913)296-1561
JeanaPhelps
Radiation Control Branch
Department of Health Services
Cabinet for Human Resources
275 East Main Street
Frankfort, KY 40601
(502)564-3700
Louisiana Matt Schlenker
Louisiana Department of
Environmental Quality
P.O. Box 82135
Baton Rouge, LA 7C;84-2135
(504)925-7042 '
1-800-256-2494 in state
Maine BobStilwell
Division of Health Engineering
Department of Human Services
State House, Station 10
Augusta, ME 04333
(207)289-5676
1-800-232-0842 in state
Maryland Leon J. Rachuba
Radiological Health Program
Maryland Department of the v
Environment
2500 Broening Highway
Baltimore, MD 21224
(410)631-3301
1-800-872-3666 In State
Massachusetts William J. Bell
Radiation Control Program
Department of Public Health
23 Service Center
Northampton, MA 01060
(413)586-7525
1-800-445-1255 in state
Michigan SueHendershott
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 Reprmted 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
1-8QO-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
Montana Adrian C. Howe
Occupational Health Bureau
Montana Department of Health arid
Environmental Sciences
Cogswell Building A113
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, ME 68509
(402)471-2168
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
Protection
CN415
Trenton, NJ 08625-0145
(609) 987-6369
1-800-648-0394 in state
New Mexico William M. Floyd
Radiation Licensing and Registration
Section
New Mexico Environmental
Improvement Division
' 1190 St. Francis Drive
Santa Fe,NM 87503
(505)827-4300
New York William J. Condon
Bureau of Environmental Radiation
Protection
New York State Health Department
Two University Place
Albany, NY 12202
(518) 458-6495
1-800-458-1158 in state
North Carolina Dr. Felix Fong
Radiation Protection Division
Department of Environmental Health
and Natural Resources
70 IBarbour Drive
Raleigh, NC 27603-2008
(919) 571-4141
1-800-662-7301 (recorded info x4196)
North Dakota Arlen Jacobson
North Dakota Department of Health
1200 Missouri Avenue, Room 304
P.O. Box 5520
Bismarck, ND 58502-5520
(701)221-5188
Ohio Marcie Matthews
Radiological Health Program
Department of Health
1224 Kinnear Road - Suite 120
Columbus, OH 43212
(614)644-2727
1-800-523-4439 in state
n-30
Reprinted from USGS Open-File Report 93-292
-------
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
Gene Smith
Radiation Protection Division
Oklahoma State Department of
Health
P.O. Box 53551
Oklahoma City, OK 73152
(405) 271-5221
George Toombs
Department of Human Resources
Health Division
1400 SW 5th Avenue
Portland, OR 97201
(503)731-4014
Michael Pyles
Pennsylvania Department of
Environmental Resources
Bureau of Radiation Protection
P.O. Box 2063
Harrisburg, PA 17120
(717)783-3594
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
EdmundAicand
Division of Occupational Health and
Radiation ,
Department of Health
205 Cannoh Building
Davis Street
Providence, RI02908
(401)277-2438
Bureau of Radiological Health
Department of Health and
Environmental Control
2600 Bull Street
Columbia, SC 29201
(803)734-4631
1-800-768-0362
South Dakota MikePochop
Division of Environment Regulation
Department of Water and Natural
Resources
, Joe Foss Building, Room 217
523 E.Capitol
Pierre, SD 57501-3181
(605) 773-3351
Tennessee Susie Shimek ,
Division of Air Pollution Control
Bureau of the Environment
Department of Environment and
Conservation
Customs House, 701 Broadway
Nashville, TN 37219-5403
(615)532-0733
1-800-232-1139 in state
Texas Gary Smith
Bureau of Radiation Control
Texas Department of Health
1100 West 49th Street
Austin, TX 78756-3189
(512)834-6688
Utah John Hultquist
Bureau of Radiation Control
Utah State Department of Health
288 North, 1460 West
P.O. Box 16690
Salt Lake City, UT 84116-0690
(801)536^250
Vermont Paul demons
Occupational and Radiological Health
Division
Vermont Department of Health
10 Baldwin Street
Montpelier, VT 05602
(802)828-2886
1-800-640-0601 in state
Virgin Islands Contact the U.S. Environmental
Protection Agency, Region II
in New York
(212)264-4110
11-31 Reprinted from USGS Open-File Report 93-292
-------
Virginia Shelly Ottenbrite
Bureau of Radiological Health
Department of Health
109 Governor Street
Richmond, VA 23219
(804)786-5932
1-800-468-0138 in state
»
Washington Kate Coleman
Department of Health
Office of Radiation Protection
Airdustrial Building 5, LE-13
Olympia, WA 98504
(206)753-4518
1-800-323-9727 In State
West Virginia BeattieL.DeBord
Industrial Hygiene Division
West Virginia Department of Health
151 llth Avenue
South Charleston, WV 25303
(304) 558-3526
1-800-922-1255 In State
Wisconsin Conrad Weiffenbach
Radiation Protection Section
Division of Health
Department of Health and Social
Services
P.O. Box 309
Madison, WI53701-0309
(608) 267-4796
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
11-32 Reprinted from USGS Open-File Report 93-292
-------
STATE GEOLOGICAL SURVEYS
May, 1993
Alabama Ernest A. Mancini
Geological Survey of Alabama
P.O. Box 0
420 Hackberry Lane
Tusealoosa, AL 35486-9780
(205)349-2852
Alaska
Thomas E. Smith
Alaska Division of Geological &
Geophysical Surveys
794 University Ave., Suite 200
Fairbanks, AK 99709-3645
(907)479-7147
Larry D. Fellows
Arizona Geological Survey
845 North Park Ave., Suite 100
Tucson, AZ 85719
(602) 882-4795
Arkansas Norman F. Williams
- Arkansas Geological Commission
Vardelle Parham Geology Center
3815 West Roosevelt Rd.
Little Rock, AR 72204
(501)324-9165 .
California James F. Davis
California Division of Mines &
Geology
801 K Street, MS 12-30
Sacramento, CA 95814-3531
(916)445-1923
Colorado Pat Rogers (Acting)
Colorado Geological Survey
1313 Sherman St., Rm 715
Denver, CO 80203
(303) 866-2611
Connecticut Richard C. Hyde
Connecticut Geological & Natural
History Survey
165 Capitol Ave., Rm. 553
Hartford, CT 06106
(203)566-3540
Delaware Robert R. Jordan
Delaware Geological Survey
University of Delaware
101 Penny Hall
Newark, DE 19716-7501 l
(302)831-2833
Florida WalterSchmidt
Florida Geological Survey
903 W. Tennessee St.
Tallahassee, FL 32304-7700
(904)488-4191
Georgia William H. McLemore
Georgia Geologic Survey
Rm.400
19 Martin Luther King Jr. Dr. SW
Atlanta, GA 30334
(404)656-3214
Hawaii Manabu Tagomori
Dept. of Land and Natural Resources
Division of Water & Land Mgt
P.O. Box 373
Honolulu, ffl 96809
(808)548-7539
Idaho Earl H. Bennett \ ,
Idaho Geological Survey
University of Idaho
Morrill Hall, Rm. 332
Moscow, ID 83843
(208) 885-7991
Illinois Morris W. Leighton
Illinois State Geological Survey
Natural Resources Building
. 615 East Peabody Dr.
Champaign, IL 61820
(217)333-4747
Indiana Norman C. Hester
Indiana Geological Survey
611 North Walnut Grove
Bloomington, IN 47405
(812)855-9350
Iowa Donald L. Koch
Iowa Department of Natural Resources
Geological Survey Bureau
109 Trowbridge Hall
Iowa City, IA 52242-1319 ""
(319) 335-1575
Kansas Lee C.Gerhard
Kansas Geological Survey
1930 Constant Ave., West Campus
University of Kansas
Lawrence, KS 66047
(913)864-3965
11-33 Reprinted from USGS Open-File Report 93-292
-------
Kentucky Donald C. Haney
Kentucky Geological Survey
University of Kentucky
228 Mining & Mineral Resources
Building
Lexington, KY 40506-0107
(606)257-5500
»
Louisiana William E. Marsalis
Louisiana Geological Survey
P.O. Box 2827
University Station
Baton Rouge, LA 70821-2827
(504) 388-5320
Maine Walter A. Anderson
Maine Geological Survey
Department of Conservation
State House, Station 22
Augusta, ME 04333
(207) 289-2801
Maryland Emery T. Cleaves
Maryland Geological Survey
2300 St. Paul Street
Baltimore, MD 21218-5210
(410) 554-5500
Massachusetts Joseph A. Sinnott
Massachusetts Office of
Environmental Affairs
100 Cambridge St., Room 2000
Boston, MA 02202
(617) 727-9800
Michigan R. Thomas Segall
Michigan Geological Survey Division
Box 30256
Lansing, MI 48909
(517)334-6923
Minnesota Priscilla C. Grew
Minnesota Geological Survey
2642 University Ave.
St. Paul, MN 55114-1057
(612) 627-4780
Mississippi S. Cragin Knox
Mississippi Office of Geology
P.O. Box 20307
Jackson, MS 39289-1307
(601) 961-5500
Missouri James H. Williams
Missouri Division of Geology &
Land Survey
111 Fairgrounds Road
P.O. Box 250
Rolla, MO 65401
(314) 368-2100
Montana Edward T. Ruppel
Montana Bureau of Mines & Geology
Montana College of Mineral Science
and Technology, Main Hall
Butte, MT 59701
(406)496-4180
Nebraska Perry B. Wigley
Nebraska Conservation & Survey
Division
113 Nebraska Hall
University of Nebraska
Lincoln, NE 68588-0517
(402)472-2410
Nevada Jonathan G. Price
Nevada Bureau of Mines & Geology
Stop 178
University of Nevada-Reno
Reno, NV 89557-0088
(702)784-6691
New Hampshire Eugene L.Boudette
Dept. of Environmental Services
117 James Hall
University of New Hampshire
Durham, NH 03824-3589
(603)862-3160
New Jersey Haig F. Kasabach
New Jersey Geological Survey
P.O. Box 427
Trenton, NJ 08625
(609)292-1185
New Mexico Charles E. Chapin
New Mexico Bureau of Mines &
Mineral Resources
Campus Station
Socorro, MM 87801
(505)835-5420
New York Robert H. Fakundiny ,
New York State Geological Survey
3136 Cultural Education Center
Empire State Plaza
Albany, NY 12230
(518)474-5816
11-34 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
Ohio 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
lOOE.Boyd
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
. (503)731-4600
Pennsylvania Donald M. HosMns
Dept. of Environmental Resources
Bureau of Topographic & Geologic
Survey .
P.O. Box 2357
Harrisburg, PA 17105-2357
(717)787-2169 -
Puerto Rico Ramtin M. Alonso .
Puerto Rico Geological Survey
Division
Box 5887
Puerta de Tierra Station
San Juan, P.R. 00906
(809)722-2526
Rhode Island . J. Allan Cain
Department of Geology
University of Rhode Island
315 Green Hall
Kingston, RI02881
(401)792-2265
South Carolina Alan-Jon W. Zupan (Acting)
South Carolina Geological Survey
5 Geology Road
Columbia, SC 29210-9998 >,
(803)737-9440
South Dakota C.M. Christensen (Acting)
South Dakota Geological Survey
Science Center
University of South Dakota
Vermiliion, SD 57069-2390
(605)677-5227
Tennessee Edward T.Luther
Tennessee Division of Geology
13th Floor, L & C Tower
401 Church Street
Nashville, TN 37243-0445 -
(615)532-1500
Texas William L. Fisher
Texas Bureau of Economic Geology
University of Texas
University Station, Box X
Austin, TX 78713-7508
(512)471-7721
Utah M. Lee Allison
Utah Geological & Mineral Survey
2363 ;S. Foothill Dr.
Salt Lake City, UT 84109-1491
(801)467-7970
Vermont Diane L. Conrad
Vermont Division of Geology and
, Mineral Resources
103 South Main St.
Waterbury.VT 05671
(802)244-5164
Stanley S. Johnson
Virginia Division of Mineral
Resources
P.O. Box 3667
Charlottesville, VA 22903
(804)293^5121
Washington Raymond Lasmanis
Washington Division of Geology &
Earth Resources
Department of Natural Resources
P.O. Box 47007
Olympia, Washington 98504-7007
(206)902-1450
11-35 Reprinted from USGS Open-File Report 93-292
-------
West Virginia Larry D. Woodfork
West Virginia Geological and
Economic Survey
Mont Chateau Research Center
P.O. Box 879
Morgantown, WV 26507-0879
(304)594-2331
*
Wisconsin James Robertson
Wisconsin Geological & Natural
History Survey
3817 Mineral Point Road
Madison, WI 53705-5100
(608) 263-7384
Wyoming Gary B. Glass
Geological Survey of Wyoming
University of Wyoming
Box 3008, University Station
Laramie, WY 82071-3008
(307) 766-2286
11-36 Reprinted firom USGS Open-File Report 93-292
-------
EPA REGION 7 GEOLOGIC RADON POTENTIAL SUMMARY
, . - by ' '-.'..'
R. Randall Schumann, James K.Otton, and Sandra L.Szarzi
U.S. Geological Survey
EPA; Region 7 includes the states of Iowa, Kansas, Missouri, and Nebraska. For each
state, geologic radon potential areas were delineated and ranked on the basis of geologic, soil,
housing construction, and other factors. Areas in which the average screening indoor radon level
of all homes within the area is estimated to be greater than 4 pGi/L were tanked high. Areas in
which the average screening indoor radon level of all homes within the area is estimated to be
between 2 and 4 pCi/L were ranked moderate/variable, and areas in which the average screening
indoor radon level of all homes within the area is estimated to be less than 2 pCi/L were ranked
low. Information on the data used and on the radon potential ranking scheme is given in the
introduction chapter. More detailed information on the geology and radon potential of each state in
Region 7 is given in the individual state chapters. The individual chapters describing the geology
and radon potential of the four states in EPA Region 7, though much more detailed than this
summary, still are generalized assessments and there is no substitute for having a home tested.
Radon levels, both high and low, can be quite localized, and within any radon potential area homes
with indoor radon levels both above and below the predicted average will likely be found.
Figure 1 shows the geologic radon potential areas in EPA Region 7. Figure 2 shows
average screening indoor radon levels in EPA Region 7 by county. The data for each state are
from the State/EPA Residential Radon Survey and reflect screening charcoal canister
measurements. Figure 3 shows the geologic radon potential of areas in Region 7, combined and
summarized, irom c'l.c individual state chapters. Many rocks and soils in EPA Region 7 contain
ample radon source material (uranium and radium) and have soil permeabilities sufficient to
produce moderate or high radon levels in homes. The following sections summarize the geologic
radon potential of each of thfc four states in Region 7. More detailed discussions may be found in
the individual state radon potential chapters for the states in Region 7.
IOWA
Pre-Illinoian-age glacial deposits cover most of Iowa, and are at or near the surface in the
southern, northwestern, and much of the northeastern parts of the state. These deposits generally
consist of calcium-carbonate-rich loam and clay loam till containing pebbles and cobbles of granite,
gabbro, basalt, rhyolite, greenstone, quartzite, chert, diorite, and limestone. Pre-Illinoian tills are
covered by from less than 1 m to more than 20 rn of Wisconsinan loess (windblown silt) in
western, southern, and eastern Iowa. Illinoian glacial deposits occur'a relatively small area along
the Mississippi River in southeastern Iowa. These deposits consist of loamy to locally sandy till
containing clasts of limestone and dolomite, with lesser amounts of igneous and metamorphic s
rocks, sandstone, and coal fragments. Illinoian deposits are covered by 1-5 m of loess.
Wisconsinan drift is represented by the Gary and Tazewell drifts, consisting of calcareous loamy
till containing clasts of shale, limestone, and dolomite, with minor amounts of basalt, diabase,
granite, chert, and sandstone. Gary drift (now called the Dows Formation), which represents
deposits of the Des Moines lobe, is generally not loess-covered; Tazewell drift is covered by as
much as 2 m of loess.
m-1 Reprinted from USGS Open-File Report 93-292-G
-------
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The aeroradioactivity signature of surface deposits in Iowa, especially the Des Moines lobe
deposits and other areas in which the loess cover is dicontinuous or absent, seems lower than
would be expected in light of the elevated indoor radon levels. This may be because much of the
radium in the near-surface soil horizons mav have been leached and transported downward in the
soil profile, giving a low surface radiometric signature wnile generating significant radon at depth
(1-2 m? or greater),to produce elevated indoor radon levels. -For example, a large area of low
radioactivity (<1.5 ppm eU) in the northern part of the State corresponds roughly to the Des
Moines lobe and the lowan erosion surface, an area directly east of the Des Moines lobe in
northeastern Iowa that is underlain by Pre-Illinoian glacial deposits and loess. However, these
areas have high geologic radon potential. Most of the remainder of the State has eU values in the
1.5-2.5 ppm range. In general, soils developed from glacial deposits can be more rapidly leached
of mobile ions than their bedrock counterparts, because crushing and grinding of the rocks by
glacial action gives soil weathering agents (mainly moisture) better access to soil and mineral grain
surfaces. Grinding of the rocks increases the mobility of uranium and radium in the soils by '.,
exposing them at grain surfaces, enhancing radidnucUde mobility and radon emanation. In
addition, poorly-sorted glacial drift may in many cases have higher permeability than the bedrock
from which it is derived. Cracking of clayey glacial soils during dry periods can create sufficient
permeability for convective radon transport to occur. This may be an important factor causing
elevated radon levels in areas underlain by clay-rich glacial deposits.
Loess-covered areas have a higher radiometric signature than loess-free areas, and also
appear to correlate roughly with higher average indoor radon levels than loess-free areas, although
all areas of Iowa have average indoor radon levels exceeding 4 pCi/L. The Loess-Covered Drift
Plains, which cover northwestern Iowa and all of southern Iowa, are underlain by Pre-Illinoian
and Illinoian glacial deposits, and loess. The Loess-Covered Drift Plains have overall high radon
potential. Valley bottoms with wet soils along the Mississippi :and Missouri Rivers may have
locally moderate to low radon potential because the gas permeability of'the soils is extremely low
due to the water filling the pore spaces. ,
The Paleozoic Plateau, in northeastern Iowa, is underlain primarily by Ordovician
carbonate and Cambrian, sandstone bedrock covered by varying amounts of Quaternary glacial
deposits and loess. It was originally thought to have been unglaciated because it is deeply
dissected and lacks glacial landforms. However, small patches of Pre-Dlinoian drift have been
preserved on uplands, indicating that at least part of the area had been glaciated. The Paleozoic
Plateau also has high geologic radon potential. Soils developed from carbonate rocks are derived
from the residue that remains after dissolution of the calcium carbonate that makes up the majority
of the rock, including heavy minerals and metals such as uranium, and thus they may contain
somewhat higher concentrations of uranium or uranium-series radionuclides than the parent rock.
Residuum from weathered carbonate rocks may be a potential radon source if a structure is built on
such a residual soil, or if the residuum constitutes a significant part of a till or other surficial
deposit. In some areas underlain by carbonate bedrock, solution features such as sinkholes and
caves increase the overall permeability of the rocks in these areas and generally increase the radon
potential of these rocks, but few homes are built directly over major solution features.
KANSAS . ' , / ' ' - -
Almost all of the bedrock exposed at the'surface in Kansas consists of sedimentary units
ranging in age from Mississippian to Quaternary. Igneous rocks native to Kansas and exposed at
ffl-5 Reprinted from USGS Open-File Report 93-292-G
-------
the surface are small localized exposures of Cretaceous laniproite in Woodson County and
Cretaceous kimberlite in Riley County. Sedimentary rocks of Mississippian age underlie the
extreme southeastern corner of the State. They consist primarily of limestones but also include
shale, dolomite, chert, sandstone, and siltstone. Pennsvlvanian rocks underlie approximately the
eastern one-quarter of the State. They consist of an alternating sequence of marine and nonmarine
shale, limestone, sandstone, and coal, with lesser amounts of chert and conglomerate. The shales
range from green and gray (low organic content) to black (organic rich). Permian rocks are
exposed in east-central and southern Kansas and consist of limestone, shale, gypsum, anhydrite,
chert, siltstone, and dolomite. Red sandstone and shale of Permian age underlie the Red Hills
along the southern border of Kansas. , ,
The Mississippian, Pennsylvanian, and Permian rocks in eastern Kansas have relatively
low uranium contents, generally low to moderate permeability and have generally low to moderate
geologic radon potential. Homes situated on Pennsylvanian arid Permian carbonate rocks
(limestones and dolomites) may have locally elevated indoor radon levels if the limestones have
developed clayey residual soils and(or) if solution features (karst topography), are present in the
area. Because of the geologic variability of these units, the Mississippian, Pennsylvanian, and
Permian rock outcrop area has been ranked moderate or variable in overall geologic radon
potential. Homes sited on Pennsylvanian black shale units may be subject to locally high indoor
radon levels. This may be the case in the Kansas City area, part of which is underlain by black
shales. -
Some elevated indoor radon levels in the northern part of the Permian outcrop area,
specifically in Marshall, Clay, Riley, Geary, and Dickinson Counties, may be related to faults and
fractures of the Mid-Continent Rift and Nemaha Uplift. Many of the subsurface faults reach and
displace the surface sedimentary rock cover, and the density and spacing of faults and fractures
within the rift zone is relatively high. Fault and shear zones are commonly areas of locally elevated
radon because these zones typically have higher permeability than the surrounding rocks, because
they are preferred zones of uranium mineralization, and because they are potential pathways
through which uranium-, radium-, and(or) radon-bearing fluids and gases can migrate.'. ,
Cretaceous sedimentary rocks underlie much of north-central and central Kansas, and
consist of green, gray, and black shale, sandstone, siltstone, limestone, chalk, and chalky shale.
A discontinuous layer of loess of varying thickness covers the Cretaceous rocks in many areas,
particularly in the western part of the Cretaceous outcrop area. Cretaceous rocks in Kansas contain
sufficient uranium to generate elevated indoor radon levels. Soils developed on Cretaceous rocks
have low to moderate permeability, but the shale-derived soils with low permeability to water likely
have moderate permeability to soil gas when they are dry due to desiccation cracks. Areas
underlain by these rocks have an overall high radon potential. Tertiary rocks cover much of
western Kansas, though they are covered by loess deposits in many areas. Tertiary rocks consist
of nonmarine sandstone, siltstone, and shale; volcanic ash deposits; and unconsolidated gravel,
sand, silt, and clay. Areas underlain by the Tertiary Ogallala Formation have a moderate
radioactivity signature and a moderate to high radon potential.
Loess ranging from 6 to more than 30 meters in thickness covers as much as 65 percent of
the surface of Kansas and is thickest and most extensive in the western and north-central parts of
the State and in proximity to glacial deposits in the northeastern corner of the State. Possible
sources for the loess include: (1) glacial outwash, (2) sand dunes in the Arkansas and Cimarron
River valleys or elsewhere (such as the Sand Hills of Nebraska), and (3) erosion of Tertiary
sedimentary rocks by wind and rivers. Radon potential of loess-mantled areas depends on the
m-6 Reprinted from USGS Open-File Report 93-292-G
-------
thickness and source of the loess. In areas of very thin loess cover, the radon potential of the ,
underlying bedrock is significant, and the loess both generates radon and transmits radon from the
underlying bedrock, whereas if the loess is more than 7-10 m thick, it is probably the sole radon
source for homes in the area. Loess-covered areas underlain by Cretaceous and Tertiary bedrock
appear to have variably moderate to high radon potential across the State, and locally elevated
indoor radon levels may be expected anywhere within areas underlain by these units. Areas
underlain by loess-covered Pennsyrvanian and Permian rocks appear to generate mainly moderate
to locally elevated indoor radon levels.
Areas of windblown sand in the Arkansas and Cimarron River valleys have low uranium
contents and low radon potential, but few homes' are built directly on the sand dunes. The dune
sands are intermixed with loess in parts of the Arkansas and Cimarron valleys, and the radon
potential may be related to the relative proportions of sand, loess, and bedrock within these areas.
Areas underlain by dune sand are expected to have lower radon levels, areas with,considerable
loess content are expected to have moderate to locally elevated radon levels. Where sand or loess
is thin or absent, the radon levels in homes on Tertiary or Cretaceous bedrock are also expected to
generally fall into the moderate to high category. '
The area within the glacial limit in northeastern Kansas is underlain by discontinuous
glacial drift and loess. The glacial deposits consist of a clay, silt, or sand matrix with cobbles and
boulders of igneous and metamorphic rocks derived from as far away as the Lake Superior Region
and southwestern Minnesota. The glacial deposits are discontinuous and till thickness varies
markedly within the area, most likely because post-glacial erosion has removed and redistributed
significant amounts of drift. Because the loess in this area is likely derived from nearby glacial
drift, and because glacial deposits are known to generate elevated indoor radon levels throughout
the northern Great Plains, this area should be considered to have a moderate to locally high radon
potential. .
MISSOURI -
Missouri lies within the stable midcontinent area of the United States. The dominant
geologic feature is the Ozark uplift in the southeastern part of the state which forms the Ozark
Plateau Province. Precambrian crystalline rocks form the core of the uplift and crop out along its
eastern side. Paleozoic sedimentary rocks dip away from this core in all directions. To the north,
northwest, and west of the uplift these sedimentary sequences are folded into broad arches and
sags. The Precambrian core of the Ozark uplift is primarily granite and rhyolite. Much of this rock
is slightly enriched in uranium (2.5-5.0 ppm). The Precambrian core is surrounded by Cambrian
and Ordovician sandstone, dolostone, shale, cherty dolostone, chert, and limestone.
Pennsylvanian sandstone, shale and clay crop out in the north-central part of the uplift. To the
north and west of the uplift, Mississippian and Pennsylvanian shale, limestone, sandstone, clay,
coal, and fire clay occur. Silurian and Devonian sedimentary rocks crop out in central Missouri
along the Missouri River and along the Mississippi River northeast of St Louis and in Cape
Girardeau and Perry Counties south of St. Louis.
Uraniferous granites and rhyolites, and residuum developed on carbonate rocks in the
Ozark Plateau Province are likely to have significant percentages of homes with indoor radon levels
exceeding 4 pCi/Li The most likely areas are those where elevated eU values occur. Where
structures are sited on somewhat excessively drained soils in this area the radon potential is further
increased. Extreme indoor radon levels may be expected where structures are sited on uranium
m-7 Reprinted from USGS Open-File Report 93-292-G
-------
occurrences and where the disturbed zone around a foundation is connected to solution openings in
carbonate rocks or to open zones in soil and bedrock caused by mine subsidence.
The Ozark Plateau Province has a moderate overall radon potential. Several areas of
somewhat excessively drained soils, scattered uranivm occurrences, residual carbonate soils in
which uranium has been concentrated, and areas of karst may generate locally elevated indoor
radon levels in this,area. The St. Francois Mountains have high radon potential owing to elevated
levels of uranium in soils developed on granitic and volcanic rocks throughout these mountains and
substantial areas of somewhat excessively to excessively drained soils.
The permeability of soils and subsoils in karst areas has been enhanced by solution
openings in and near carbonate pinnacles and by zones of solution collapse. Where soils
developed on such carbonate rocks are thin, foundations may encounter open bedrock fractures in
the limestone. Karst underlies parts of the City and County of St. Louis and may locally cause
elevated indoor radon levels. Elevated eU and significant karst development occur in Perry and
Cape Girardeau Counties. Structures sited on locally highly permeable karst soils with elevated eU
in these two counties will likely have elevated indoor radon levels. Broad karst areas have formed
by dissolution of carbonate rocks in the central and western Ozark Plateau, the southern Osage
Plain, and along the Mississippi River from Cape Girardeau County to Rails County. These
carbonate regions have overall moderate radon potential. However, areas of intense karst
development, elevated uranium in residual soils developed on carbonate, and large areas of
somewhat excessively drained to excessively drained soils may cause locally high indoor radon
levels to occur.
Several very thin, highly uraniferous (as much as 180 ppm), black, phosphatic shales
occur in the Devonian and Pennsylvanian sedimentary rock sequences in the unglaciated Osage
Plain of southwestern Missouri. Elevated indoor radon levels may be expected where the
foundations of structures intercept the thin Pennsylvanian uraniferous shales or the Chattanooga
Shale in the southwestern part of the state from Kansas City south to McDonald and Barry
Counties and in north-central Missouri in Boone, Randolph and Macon Counties, or where they
intercept well-drained alluvium derived from these rocks. Because these uraniferous shales are so
thin, such circumstances are likely to be very site- or tract-specific; thus detailed geologic and soil
mapping will be necessary to outline areas of potential problems. Where these shales are jointed or
fractured or soils formed on them are somewhat excessively drained on hillslopes, the radon
potential is further increased. Residuum developed on limestones associated with these
uraniferous shales may also have elevated uranium levels and have significant radon potential. The
unglaciated Osage Plain province has a low overall radon potential; however, areas of thin soils
underlain by the uraniferous shales in this province have high radon potential with locally extreme
values possible.
Along the Missouri and Mississippi River valley floor, alluvial deposits (silt, sand, and
gravel) dominate. Loess deposits occur on the flanks of the river valleys in several areas and are
especially widespread in Platte, Buchanan, Holt, and Atchison Counties along the Missouri River
north of Kansas City. AEuvium and loess along the upper Missouri River Valley upstream from
Kansas City seem to be producing elevated indoor radon levels that may be related to the somewhat
elevated uranium content of these materials and, possibly, to elevated radon emanation and
diffusion associated with well-drained loess deposits. Detailed studies of indoor radon data in this
area would be necessary to determine more closely the origin of elevated indoor radon levels.
Thin, somewhat excessively drained soils developed on limestone that occur as part of one soil
ffl-8 Reprinted from USGS Open-File Report 93-292-G
-------
association in the southern suburbs of Kansas City may also be related to elevated indoor radon
levels in Jackson County.
The northernmost part of the Mississippi Embayment occupies the southeastern corner of
the state and'forms die Coastal Plain Province, or southeastern lowlands. This area is underlain by
Tertiary and Quaternary alluvium. The Coastal Plain Province has a low radon potential overall.
Only one value exceeding 4 pCi/L is reported for a six-county area, and very poorly drained soils
are widespread. However, some aeroradiometric anomalies occur in this area, and some
excessively drained soils occur locally. Elevated indoor radon levels may be associated with these
locales. Although elevated eU occurs over some of the sedimentary rocks in this province, the
high soil moisture, the very poorly drained soils; and the low indoor radon values all point towards
low radon potential. \
The surficial geology north of the Missouri River is dominated by glacial deposits covered
with a thin veneer of loess; however, several areas of residual soils developed on underlying
sedimentary rocks occur in the eastern and western parts of this region. Residual.soils are those
soils formed by weathering of the material beneath the soil. These surficial deposits (both glacial
deposits and residuum) are generally 50-200 feet thick, but they locally exceed 200 feet along the
northern edge of the state. The dissected till plain of northern Missouri has moderate overall radon
potential, although elevated indoor radon levels are common in areas of similar geology in adjacent
states, particularly Iowa, Nebraska (fig. 1), and Illinois. Except for counties along the Missouri
River, the indoor radon data for the counties in the dissected till plain are sparse and appear to be
generally in the low to moderate range.
NEBRASKA
Rocks ranging in age from Penrtsylvanian to Quaternary are exposed in Nebraska.
Pennsylvanian rocks are exposed in southeastern Nebraska and include limestones, shales, and
sandstones. Only some of the Upper Pennsylvanian strata are exposed in Nebraska; these rocks
are a repeated sequence of marine shales and limestones alternating with nonmarine sandstones and
shales, and thin coals. Exposed Permian rocks consist of green, gray, and red shales, limestone,
and gypsum. Exposures of Pennsylvanian and Permian rocks are generally limited to valley sides
along streams because much of the eastern part of the State is mantled with Pleistocene glacial,
deposits and loess. Black shales of Pennsylvanian age may constitute a significant radon source
where the shales are a source component of the glacial tills.
Cretaceous rocks are exposed in much of .eastern Nebraska, in parts of northern and
northwestern Nebraska, and along the Republican River Valley. Lower Cretaceous rocks consist
of sandstones, shales, and thin coals. Upper Cretaceous rocks consist primarily of shale,
limestone, and sandstone. The Upper Cretaceous Pierre Shale consists of gray, brown, and black
shales, with thin layers of bentonite, chalk, limestone, and sandstpne. Although the permeability
of soils developed on the Pierre Shale is listed as low, the shales contain numerous fractures and
partings and are likely to have sufficient permeability for radon transport during dry periods. The
stratigraphicaily lowest unit in the Pierre Shale is the Sharon Springs Member, a black shale of
widespread .occurrence in Nebraska, South Dakota, Kansas, and Colorado. The Sharon Springs
Member is exposed in a relatively broad area along the Niobrara and Missouri Rivers from Keya
Paha to Cedar Counties and along the Republican River in southern Nebraska, The gray-shale
units of the Pierre Shale, while not as uraniferous as the black shale of the Sharon Springs
Member, generally Contain higher-than-average (i.e., >2.5 ppm) amounts of uranium and are
m-9 Reprinted from USGS Open-File Report 93-292-G
-------
correlated with elevated indoor radon levels in several areas. Outcrops of the Pierre Shale in the
northwestern corner of Nebraska have the highest surface radioactivity in the State. Areas
underlain by Cretaceous rocks, particularly the Pierre Shale, have overall high radon potential.
Tertiary rocks have the most widespread exposure in the State. The White River Group
consists of mudstone, siltstone, sandstone, and thin layers of volcanic ash, and is exposed in the
North and South Platte valleys and in northwestern Nebraska. The Arikaree Group overlies the
White River Group and consists of siltstone and sandstone. The Tertiary Ogallala Group covers
about two-thirds of the State. It consists of sandstone, siltstone, gravel, sand, silt, clay, and thin
volcanic ash layers. The Ogallala is covered by the Sand Hills, an area of Quaternary windblown
sand deposits, in the north-central part of Nebraska. Pre-Sand Hills sediments of Pliocene and
Quaternary age also overlie portions of the Ogallala in this area. The Ogallala, Arikaree, and White
River Groups all have high surface radioactivity (for purposes of this report, high radioactivity is
defined as greater than 2.5 ppm eU) and are known to host uranium deposits. Soils developed on
the Tertiary units have moderate permeability and generate moderate to locally high indoor radon.
The White River and Arikaree Groups have significant amounts of uranium-bearing volcanic glass
and may be somewhat more likely to generate elevated indoor radon concentrations. Areas
underlain by Tertiary sedimentary rocks have overall moderate radon potential. Some homes in
this area are likely to have high indoor radon levels, particularly those sited on uranium-bearing
parts of the White River and Arikaree Groups in northwestern Nebraska.
Eastern Nebraska and southern Nebraska south of the Platte River are underlain by
Permian through Tertiary rocks mantled with Pleistocene glacial deposits of Pre-Dlinoian age and
loess. The glacial deposits generally consist of a clay, silt, or sand matrix with pebbles and
cobbles of limestone, igneous rocks, and quartzite. Source material for the glacial deposits
includes locally-derived Permian and Pennsylvanian limestone and shale and Cretaceous sandstone
and shale, as well as lesser amounts of sandstone, limestone, shale, and igneous and metamorphic
rocks from bedrock sources to the north and northeast. Of the source rocks underlying the glacial
deposits and those to the north and northeast, Cretaceous sandstones and shales, Pennsylvanian
black shales, and Precambrian crystalline rocks all contain sufficient amounts of uranium-series
radionuclides (uranium and(or) radium) to generate radon at elevated levels.
Loess covers most of the glacial deposits in eastern Nebraska as well as bedrock in the
south-central part of the State. Loess is a generally 'good radon source because it consists of silt
and clay-sized particles, which are more likely to be associated with radionuclides and have higher
emanation coefficients than larger sized particles, and it typically has moderate permeability,
Average indoor radon levels are consistently greater than 4 pCi/L in areas underlain by loess-
mantled glacial drift The majority of homes in the area underlain by loess-mantled bedrock in the
south-central part of the State also have radon levels exceeding 4 pCi/L, but indoor radon levels
are likely to be more variable from house to house in south-central Nebraska, depending on the
distribution, thickness, or weathering extent of the loess. Areas underlain by glacial drift and most
areas underlain by loess have overall high radon potential. The area mapped as loess between the
Platte River and the Sand Hills in the central part of the State has generally moderate radon
potential. Homes sited on thicker loess along the north side of the Platte River in Dawson and
Buffalo Counties may have locally high indoor radon levels. The Sand Hills have low surface
radioactivity and generally low radon potential.
ffl-10 Reprinted from USGS Open-File Report 93-292-G
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PRELIMINARY GEOLOGIC RADON POTENTIAL ASSESSMENT OF MISSOURI
; :. ' . - . :;,. by ' . -- .
James K. Otton
U.S. Geological Survey
INTRODUCTION
*","'', " - " -
This assessment of the radon potential of Missouri is largely dependent on geologic
information derived from publications of the Missouri Department of Natural Resources, Division
of Geology and Land Survey, and from publications of the U.S. Geological Survey. Also, an
analysis of data gathered during a radon survey in the winter of 1987-1988 by U.S. EPA and the
Missouri Department of Health is included in this report. Much information in the geographic
setting section is derived from The National Atlas of the United States of America (U.S.
Geological Survey, 1974).
This is a generalized assessment of geologic radon potential of rocks, soils, and surficial
deposits of Missouri. The scale of this assessment is such that it is inappropriate for .use in -
identifying the radon potential of small areas such as neighborhoods, individual building sites, or
housing tracts. Any localized assessment of radon potential must be supplemented with additional
data and information from the locality. Within any area of a given radon potential ranking, there
are likely to be areas with higher or lower radon levels than characterized for the area as a whole.
' Indoor radon levels, both high and low, can be quite localized, and there is no substitute for testing
individual homes. Elevated levels of indoor radon have been found in every state, and EPA
recommends that all homes be tested. For more information on radon, the reader is urged to
consult the local or State radon program or EPA regional office. More detailed information on state
or local geology may be obtained from the:State geological survey. Addresses and phone numbers
for these agencies are listed in chapter 1 of this/booklet.
GEOGRAPHIC SETTING
Missouri lies within the continental interior of the United States and extends from the
northern edge of the Gulf Coastal Plain northward to the southern edge of the glaciated plains. The
Mississippi River runs along the eastern edge of the state and the Missouri River crosses north-
central Missouri. The state can be subdivided into three major physiographic provinces (fig. 1>
the Central Lowlands, the Ozark Plateaus and the Coastal Plain or southeastern lowlands.
The Central Lowlatfds Province is divisible into two subprovinces (fig 1): the dissected till
plains north of the Missouri River (IB) and the Osage Plains in the west-central part of the state
south of the Missouri River (IA). The dissected till plains generally have 100-300 feet of relief but
include areas of smooth plains, irregular plains, and open low hills (fig. 2). In the smooth plains
more than 80 percent of the area is characterized by gentle slopes. In the irregular "plains 50-80
percent of the area is characterized by gentle slopes, whereas in the low hills 20-50 percent of the
area is underlain by gentle slopes. Bluffs along the Mississippi River north of St. Louis have
300-500 feet of local relief. In these areas, 20-50 percent of the area is.underlain by gentle slopes.
The Osage Plains are marked by smooth plains and irregular plains with 100-300 feet of local
relief. More than 80 percent of the smooth plains are gently sloping, whereas 50-80 percent of the
irregular plains are gently sloping.
IV-1 Reprinted from USGS Open-File Report 93-292-G
-------
Fig. 1- Physiographic provinces of Missouri. I- Central Lowland Province: IA- Osage
Plains, IB- Dissected till plains. H- Ozark Plateaus Province: HA- Springfield Plateau, IEB-
Salem Plateau, EC- St. Raricois Mountains. HI- Southeastern lowlands or the Coastal
Plains Province. KC- Kansas City; SL- Saint Louis. Modified from Duley, 1983.
-------
100km
Fig. 2- Land surface map of Missouri. Al- Flat plains, >80% of the land surface is gently
sloping, local relief 0-100 feet A2- Smooth plains, >80% of the land surface is gently
sloping, local relief 100-300 feet B2- Irregular plains, 50-80% of the land's surface is
gently sloping, local relief 100-300 feet B3- Tablelands, 50-80% of the land's surface is
gently sloping, local relief 300-500 feet C2- Open low hills, 20-50% of the land's surface
is gently sloping, local relief 100-300 feet C3- Open hills, 20-50% of the land's surface is
gently sloping, local relief 300-500 feet D4-High hills, <20% of the land's surface is
gently sloping, local relief 500-1000 feet Map modified from The National Atlas of the
United States of America.
-------
The Ozark Plateaus Province includes the Springfield Plateau (DA), the Salem Plateau
(EDB), and the St Francois Mountains (EC) (fig. 1). This area includes tablelands and open hills
of moderate relief (300-500 feet) and high hills with 500-1000 feet of relief (fig. 2). In the
tablelands, which lie mostly along the western edge of the area, about 50-80 percent of the surface
consists of gentle slopes that mostly occur in upland areas. The open hills have 20-50 percent of
the surface underlain by gentle slopes as compared to the high hills where less than 20 percent of
the area is gently sloping.
The Coastal Plain Province (El, fig. 1) is mostly underlain by flat plains with relief less
than 100 feet, except for a northeast-trending ridge with relief 100-300 feet that traverses the
province (fig. 2). On the flat plains, more than 80 percent of the area is gently sloping. On the
ridge, 50-80 percent of the area is gently sloping. -
Annual precipitation across the state decreases gradually from about 48 inches in the
southeast corner to about 52 inches in the northwest corner. May and June, the wettest months of
the year, have a mean monthly rainfall of four inches across most of the state. December, January,
and February are the driest months with mean monthly precipitation ranging from about 1 inch in
the northwest to nearly 4 inches in the southeast.
About half of the population of the state lives in the St. Louis and Kansas City metropolitan
areas (fig. 1). The rest of the population is fairly evenly distributed throughout the rest of the state
(fig. 3) in small cities and towns, except in the Ozark Plateau (EA, JIB,- EC, fig. 1) and the
dissected till plains (B3, fig. 1) where the population density is lower.
The Central Lowlands (JA, ffi, fig. 1) are used primarily as cropland; lesser uses include
grazing land, pasture, woodland, and forest. The Ozark Plateau (EA, EB, EC, fig. 1) includes
mostly woodland and forest with lesser areas of cropland and pasture. The Coastal Plain (El, .
fig 1) is dominantiy cropland.
GEOLOGIC SETTING
Missouri lies within the stable midcontinent area of the United States. The dominant
geologic feature is the Ozark uplift in the southeastern part of the state which forms the Ozark
Plateau Province. Precambrian crystalline rocks core the uplift and crop out along its eastern side
(fig. 4). Paleozoic sedimentary rocks dip away from this core in all directions. To the north,
northwest, and west of the uplift these sedimentary sequences are folded into broad arches and
sags. The Forest City basin occupies the northwest corner of the state. Along the northeastern
edge of the state, the sedimentary sequences dip eastward into the Illinois basin. A broad arch,
cored by Ordovician rocks, lies parallel to and just west of the Mississippi River from St. Louis
northward.
The northernmost part of the Mississippi Embayment underlies the southeastern corner of
the State and forms the Coastal Plain Province (IE, fig. 1), or southeastern lowlands. Cretaceous
and younger marine sediments were deposited in this structural sag, but the present-day surface
exposures consist mostly of Tertiary and Quaternary alluvium.
The Precambrian core of the Ozark uplift is primarily granite and rhyolite (fig. 4). Much of
this rock is slightly enriched in uranium (2.5-5.0 ppm). The Precambrian core is surrounded by
Cambrian and Ordovician sandstone, dolostone, shale, cherty dolostone, chert, and limestone.
Pennsylvanian sandstone* shale and clay crop out in the north-central part of the uplift. To the
north and west of the uplift, Mississippian and Pennsylvanian shale, limestone, sandstone, clay,
coal, and fire clay occur. Silurian and Devonian sedimentary rocks crop out in central Missouri
IV-4 Reprinted from USGS Open-File Report 93-292-G
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POPULATION (1990)
E3 0 to 10000
Q 10001 to 20000
E3 2090110100000
H 100001 to 500000
500001 to 993529
Figure 3. Population of counties in Missouri (1990 U.S. Census data).
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along the Missouri River and along the Mississippi River northeast of St Louis and in Cape
Girardeau and Perry Counties south of St. Louis (figs. 4 and 5).
Several very thin, uranium-bearing (as much as 180 ppm; Nuelle, 1987), black, phosphatic
shales occur in the Devonian and Pennsylvanian sedimentary rock sequence. They crop out
principally in west-central Missouri in Jackson, Lafayette, Cass, Johnson, Bates, Henry, Vemon,
and Barton Counties (figs. 4 and 5). North of the Missouri River these black shales are mostly
covered by glacial'deposits, but they are exposed at the surface in some areas, especially in
Randolph, Macon, and Boone Counties.
Land subsidence related to old mine workings occurs in some areas of the Ozark Plateau.
Such subsidence may locally affect soil and subsoil permeability and foundation integrity.
Uranium-bearing granite has been quarried in Iron County for dimension stone (M. Marikos,
written commun., 1986) and used locally for construction of buildings.
The surficial geology north of the Missouri River (fig. 6) is dominated by glacial deposits
covered by a thin veneer of loess (fine-grained wind blown sediment); however, several areas of
residual soils developed on underlying sedimentary rocks occur in the eastern and western parts of
this region. Residual soils are those soils formed by weathering of the material beneath the soil.
These surficial deposits (both glacial deposits and residuum) are generally 50-200 feet thick, but
they locally exceed 200 feet along the northern border of the statev
Residuum developed on sedimentary rocks dominates the area south of the Missouri River.
Here, the surficial materials are generally less than 50 feet thick, except in the eastern part of the
Ozark Plateau where residuum is typically 50-200 feet thick and locally exceeds 200 feet In the
southeastern corner of the state, thick residuum exceeding 50 feet, and locally exceeding 200 feet,
has developed on the sedimentary rocks and the younger alluvium exposed there.
Alluvial deposits (silt, sand, and gravel) are the primary surficial deposits along the
Missouri and Mississippi River valley floor. Loess deposits occur on the flanks on the river
valleys in several areas and are especially widespread in Platte, Buchanan, Holt, and Atchison
Counties along the Missouri River north of Kansas City.
Broad karst areas have formed by dissolution of carbonate rocks in the central and western
Ozark Plateau and the southern Osage Plains areas, and along the Mississippi River from Cape
Girardeau County to Rails County (fig. 7). Karst is a type of topography characterized by closed
depressions or sinkholes, caves, and underground drainage. The permeability of soils and
subsoils in karst areas has been enhanced by solution openings in and near carbonate pinnacles and
by zones of solution collapse. Where soils developed on such carbonate rocks are thin, .
foundations may encounter open bedrock fractures or solution cavities in the limestone. ,
The aeroradiometric survey of the State shows two distinctive areas (fig. 8). One, north of
the Missouri River, is a broad area with gradual changes in equivalent uranium (elJ) that range
from 1.0-2.0 ppm in the north-central part of the area to as much as 3.0 ppm in the southeastern
part of that area. The change in values likely reflects changes in the composition of the parent
material of the glacial deposits. Areas of elevated eU (defined as >2.5 ppm in this report) may
contain a higher proportion of uraniferous black shale fragments in the glacial deposits. Loess and
alluvium along the Missouri River upstream from Kansas City ranges from 2.0 to 3.0 ppm eU.
South of the Missouri River, changes in the aeroradiometric signature appear more abrupt.
Residuum developed on the rhyolites and granites comprising the core of the Ozark uplift contain
as much as 4.0 ppm eU (fig. 8). These rhyolites and granites contain modest amounts of uranium
in fresh samples; for example, six of eight sampled granites averaged greater than 3 ppm U ,
IV-7 Reprinted from USGS Open-File Report 93-292-G
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louilCity
80km
Figure 5. Missouri Counties.
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CO
oo
o\
OQ
O
.8
3
O
on
CO
o
1
f
a
CO
vo
I
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EXPLANATION FOR THE
SURFICIAL MATERIALS MAP OF MISSOURI
Alluvium - silt, sand, and gravel
Loess - silt and clayey silt
Glacial deposits - usually overlain by loess
Residuum from limestone and shale
pTT^I Residuum from shale, limestone, and sandstone
R^ Residuum from cherty limestone
| | Residuum from cherty dolomite
l-Vyvj Residuum from cherty sandstone and dolomite
E$$ 200 feet
-------
80km
Fig. 7- Map showing areas of karst in Missouri. 1- Areas of substantial karst
development 2- Areas of moderate karst development Modified from Duley (1983).
-------
Fig. 8- Aerial radiometric map of Missouri (after Duval and others, 1989). Contour lines at 1.5
and 2.5 ppm equivalent uranium (eU). Pixels shaded from 0 to 6.0 ppm elJ at 0.5 ppm eU
increments; darker pixels have lower eU values; white indicates no data.
-------
(the average for granites worldwide) and they ranged from 3 to 34 ppm U in various data sets
(Nuelle, 1987). Structures sited directly on thin, soils developed over such uraniiim-bearing
bedrock or on deep residuum in which uranium has been retained in the soil profile are likely to
have elevated indoor radon. Deep residuum developed on the Cambrian, Ordovician, and
Mississippian sedimentary rocks of the rest of the Ozark Plateau and the southern part of the Osage
.Plain ranges from 0.5 ppm to 3.5 ppm eU (fig. 8). The parts of this area with elevated eU values
probably represent residuum developed on carbonate rocks in which uranium has been retained in
the soil profile. In Pennsylvania, residuum on carbonate rocks of this age may contain as much as
8 ppm uranium (Greeman and others, 1990). Although the original limestone or dolostone may
have less than 1 ppm uranium, uranium is often retained in the soil profile by clays and iron
oxyhydroxides during dissolution of the carbonate bedrock; thus the soil becomes enriched in
uranium. Houses sited on such residuum often have elevated indoor radon readings. Elevated eU
readings (2.5-3.5 ppm) occur in Ordovician and Mississippian-age rocks in Perry, Cape
Girardeau, Bellinger, Carter, Ripley, Oregon, Howell, Texas, Barry, and Lawrence Counties
(figs. 5 and 8).
The region underlain by residuum developed on Pennsylvanian sedimentary rocks in
western Missouri has a broad northeast-trending band of elevated eU with as much as 4:0 ppm in
Henry County. This corresponds to an outcrop belt of uranium-bearing Pennsylvanian black
shales (fig. 4), notably the Mecca Quarry and Excello Shale Members of the Carbondale
Formation, the Little Osage Shale Member of the Fort Scott Limestone, and the Anna Shale
Member of the Fort Pawnee Formation (Coveney and others, 1987). These black shale beds are
typically very thin (a few tens to several tens of centimeters) but contain significant amounts of
uranium (20-170 ppm; Coveney, and others, 1987; Nuelle, 1987); the phosphatic black shales tend
.to be the most uranifefous. Such shales are also well jointed and thus have relatively high
permeability to gases. The shales are typically separated from one another by thick intervals of
coal, fire clay, gray shale, sandstone, and limestone. Detailed geologic maps are necessary for
determining where such shales occur in outcrop. Other black shales occur throughout
northwesternmost and north-central Missouri but are largely covered by glacial deposits. Where
such shales are overlain by glacial deposits, they may be incorporated in those deposits and cause
an increase in the uranium content of such deposits. Several thin black shale intervals have been
identified in the Kansas City metropolitan area (Coveney and others, 1987). Where the foundation
of a structure cuts through one of these black shale intervals, the Indoor radon levels may be high.
Locations where overlying residuum is thin and black shale bedrock is near the surface, such as on
hillslopes adjacent to stream valleys, are places where radon potential is likely to be high.
The uranium-bearing, Late Devonian and'Early Mississippian-age, Chattanooga Shale
occurs in McDonald, Newton, and Barry Counties in southwestern Missouri and in Marion, Rails,
Pike, and Lincoln Counties in northeastern Missouri (Nuelle, 1987; M. Marikos, written
commun., 1986). Uranium analyses of this unit are sparse in Missouri, however. In McDonald,
Newton, and Barry Counties, the Chattanooga crops out near the base of bluffs or underlies
alluvium in stream valleys. Homes sited in stream valleys in these areas may have elevated radon
levels.
Uranium minerals and radioactive carbonaceous material occur in fire clay pits near -
Owensvflle in southern Gasconade County and near Fulton in Callaway County (Muilenburg,
1957). Uranium minerals occur in a limestone quarry near Ste. Genevieve in Ste. Genevieve
County and in chert and limestone near Creighton in Cass County (Muilenburg, 1957).
Uraniferqus asphaltic or bituminous material occurs in dolomitic rocks near Ava in Douglas
IV-13 Reprinted from USGS Open-File Report 93-292-G
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County, in cherty residuum near West Plains and Willow Springs in Howell County, in siliceous
residuum and sandstone near Bardley in Oregon County, and in vugs in the Bonneterre Dolomite
(Upper Cambrian) near Fredericktown in Madison County (Muilenburg, 1957). Such uranium
occurrences may cause indoor radon problems if the foundations of structures are sited in rocks
and soils where they occur. Predicting the specific location of such uranium occurrences is not
possible with present information and individual site inspections may be necessary due to the
localized nature of such deposits.
SOILS
Most of Missouri lies in the mesic udic soil moisture-temperature regime (Rose and others,
1990); however, the southeastern corner of the state and the westernmost edge of the state south of
Kansas City is thermic udic. Mesic udic soils are very moist (56-96 percent pore saturation in
sandy loams, and 74-99 percent saturation in a silty clay loam) in the winter and are moderately
moist (44-56 percent saturation in sandy loams, and 58-74 percent in a silty clay loam) in the
summer. Thermic udic soils are very moist in the winter (56-96 percent pore saturation in sandy
loams, and 74-99 percent saturation in a silty clay loam) and are slightly moist in the summer
(24-44 percent pore saturation in sandy loams, and 39-58 percent pore saturation in silty clay
loams).
In places where soils are moderately moist to" very moist, soil moisture will tend to inhibit
radon migration by diffusion and flow. However, soils in which the water drains rapidly from the
soil profile because of elevated intrinsic permeability, or steep slopes, or both, may be areas where
radon may migrate more readily and the radon potential of1 that area is increased. Conversely, soils
in which the water drains away slowly because of low intrinsic permeability, low slopes, or both,
may be areas where radon migrates very slowly, and the area's radon potential is lowered.
Excessively drained soils (soils with high internal permeability or steep slope) are
uncommon in Missouri, but they do form parts of some mapped soil associations (fig. 9),
Somewhat excessively drained soils, are more common and form parts of several mapped soil
associations, principally in the Ozark Plateau and along the valley of the Missouri River,
Very slowly permeable and somewhat poorly to very poorly drained soils are also common
in Missouri, and they form varying percentages of various mapped soil associations, largely in the
eastern part of the central lowland (fig. 10), the lower Osage plain, along the lower Missouri and
Mississippi River valley floors, and in the southeastern lowland. Broad areas in which the entire
soil association is composed of very slowly permeable and somewhat poorly to poorly drained
soils occur in the eastern part of the central lowland.
INDOOR RADON DATA
The Missouri Department of Health and the U.S. EPA conducted a population-based
screening survey of indoor radon levels in Missouri (Table 1, fig. 11). Geologic interpretations of
population-based data must be made with caution because the measured houses are typically only
from a relatively few population centers in a given county and thus do not necessarily characterize
the entire county's area. For example, a county may have a relatively high radon potential on well-
drained, uranium-bearing soils on hillslopes that occur over a widespread area, but if housing is
generally located on poorly drained, low-uranium soils on the valley floor, a population-based
survey for that area will have relatively low radon values.
IV-14 Reprinted from USGS Open-File Report 93-292-G
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Areas where the soil essoclstlon
contains 1 excessively or somewhat
excessively drained soil
Areas where the soil association
contains 2 somewhat excessively
drained soils
Areas where the entire soil
association Is excessively drained
80km
Fig. 9- Map showing soil associations in Missouri where one or more mapped soils are
excessively or somewhat excessively drained. Map derived from maps and data in Soil
Conservation Service (1979).
-------
ArMt whara part of tha aell
aaaoclatlon Is vary tlowly parmaabla
ind somewhat to very poorly
drained
Area* where th* entire soil aiaoelatlon
la vary slowly parmaabla and
aomawhat poorly to poorly dralnad
80km
Fig. 10- Map showing soil associations in Missouri where one or more mapped soils are
very slowly permeable and somewhat to very poorly drained. JMap derived from maps and
data in Soil Conservation Service (1979).
-------
Bsmt.;& 1st Floor Rn
%>4pCi/L
OtolO
11 to 20
21 to 40 -
41 to 60
Missing Data
or < 5 measurements
Bsmt & 1st Floor Rn
Average Concentration (pCi/L)
^^^ 0.0 to 1.9
k\X\N 2.0 to 4.0
8 IJ 4.1 to 6.5
35 II Missing Data
or < 5 measurements
100 Miles
Hgurell. Screening indoor radon data from the EPA/State Residential Radon Survey of Missouri,
1987-1988, for counties with 5 or more measurements. Data are from 2-7 day charcoal canister
tests. Histograms in map legends show the number of counties in each category. The number of
samples in each county (See Table 1) may not be sufficient to statistically characterize the radon
levels of the counties, but they do suggest general trends. Unequal category intervals were chosen
to provide reference to decision and action levels. ^
-------
TABLE 1. Screening indoor radon data from the EPA/State Residential Radon Survey of
Missouri conducted during 1987-88. Data represent 2-7 day charcoal canister measurements
from the lowest level of each home tested.
COUNTY
ADAIR
ANDREW
ATCfflSON
AUDRAIN
BARRY
BARTON
BATES
BENTON
BOLLINGER
BOONE
BUCHANAN
BUTLER
CALDWELL
CALLAWAY
CAMDEN
CAPEGIRARDEAU
CARROLL
CARTER
CASS
CEDAR
CHARITON
CHRISTIAN
CLARK
CLAY
CLINTON
COLE
COOPER
CRAWFORD
DADE
DALLAS
DAVDSSS
DEKALB
DENT
DOUGLAS
DUNKLIN
FRANKLIN
GASCONADE
GENTRY
GREENE
GRUNDY
HARRISON
NO. OF
MEAS.
6
6
4
- 6
10
10
11
7
10
13
39
12
3
3
24
10
4
2
57
8
4
7
5
94
4
34
4
7
1
4
7
4
6
8
12
40
7
5
42
4
6
MEAN
2.4
6.5
10.8
0.9
1.9
1.1
2.8
0.9
1.8
3.0
4.5
2.4
2.3
2.1
3.3
3.1
3.2
2.5
2.1
1.3
1.6
1.1
2.0
3.8
2.6
2.4
3.1
2.5
2.7
1.1
2.0
1.6
0.8
2.9
1.5
1.8
0.6
2.2
3.8
1.3
3.3
GEOM.
MEAN
1.9
2.6
8.2
0.5
1.5
0.8
2.0
0.6
1.3
2.0
3.1
1.0
2.1
1.5
1.8
2.4'
2.8
2.4
1.6
0.9
1.3
0.9
1.7
2.5
2.0
1.6
2.2
1.0
2.7
1.0
1.3
0.8
0.5
1.4
1.1
1.4
0.4
1.6
2.2
1.2
2.6
MEDIAN
2.2
1.9
9.5
0,5
1.6
0.7
2.3
0.9
1.4
1.9
3.3
1.0
2.5
2.3
1.7
2.0
3.3
2.5
1.5
0.8
1.7
0.9
2.0
2.4
1.6
1.8
2.3
0.9
2.7
1.1
1.2
1.7
0.6
1.1
1.1
1.5
0.5
1.1
2.1
1.3
2.0
STD.
DEV.
1.7
10.7
8.2
0.8
1.4
1.1
2.2
0.6
1.6
3.1
3.8
3.9
1.3
1.6
4.8
2.9
1.8
0.1
2.0
1.6
1.0
0.6
1.3
4.5
2.4
2.0
2.7
3.4
0.0
0.5
1.7
1.5
0.7
3.8
1.3
1.5
0.4
2.2
7.8
0.4
3.2
MAXIMUM
5.6
28.0
22.0
1.9
4.5
3.4
7.0
1.7
5.1
11.9
19.9
14.4
. 3.5
3.5
22.8
10.2
4.9
2.5
10.2
5.2
2.8
2.0
4.1
25.3
6.2
8.8
6.9
9.7
2.7
1.6
4.6
3.1
1.6
10.7
4.9
6.9
1.2
6.0
51.8
1.7
9.7
%>4 pCi/L
17
33
75
0
20
0
18
0
20
23
38
8
0
0
17
20
50
0
. 14
13
0
0
20
29
25
21
25
14
0
0
29
0
0
25
8
8
0
20
24
0
17
%>20 pCi/L
0
17
25
0
0
0
0
0
0
0
0
0
0
0
4
0
0
0
0
0
0
0
0
3
0
, 0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
0
-------
TABLE 1 (continued). Screening indoor radon data for Missouri.
COUNTY
HENRY
HICKORY .
HOLT
HOWARD
HOWELL
IRON
JACKSON
JASPER
JEFFERSON
JOHNSON
KNOX
LACLEDE
LAFAYETTE
LAWRENCE
LEWIS
LINCOLN '
LINN
LIVINGSTON
MACON
MADISON
MARIES
MARION
MCDONALD
MERCER
MILLER
MISSISSIPPI
MONITEAU
MONROE
MONTGOMERY
MORGAN
NEW MADRID
NEWTON
NODAWAY
OREGON
OSAGE
OZARK
PEMISCOT
PERRY ,
PETTTS
PHELPS
PIKE
PLATTE
POLK
NO. OF
MEAS.
28
2-
2
10
15
7
271
40
49
32
3
12
34
11
1
6
5
. 2
,5
7
2
8
5
2
10
3
, 4
7
2
8
7
11
8
3
6
5
1
4
18
14
, 9
25
15
MEAN
1.6
0.6
1.8
1.8
3.6
0.8
3.9
1.5
2.8
2.3
1.2
2.0
3.5
1.5,
0.4
1.3
2.2
3.5
1.2
3.1
0.4
5.5
1.0
1.1
1.2
0.4
0.8
0.6
2.8
0.9
1.2
3.0
4,1
3.6
1.3
2.0
2.7
6.4
, 2.5
1.0
2.2
5.6
2.2
GEOM.
MEAN
1.3
0.5
1.0
1.4
2.3
0.6
2.7
1.0
1.8
1.6
0.7
0.9
2.8
1.1
0.4
0.8
2.0
3.0
1.0
2.1
0.2
3.0
= 0.4
1.1
0.9
0.3-
0.6
0.5
1.6
0.7
0.8
1.5
2.9
3.4
0.9
1.9
2.7
3.3
116
0.8
1.5
3.6
1.3
MEDIAN
1.3
0.6
1.8
1.6
2.1
ae
2.8
1.1
1.8
1.7
1.6
0.9
"3.1
1.1
0.4
0.9
2.1
3.5
1.2
1.7
0.4
3.7
0.5
, 1.1
1.0
0.2
0:7
0.7
2.8
0.8
0.8
1.4
2.4
3.1'
0.8
2.1
2.7
5.7
1.7
0.8
1.5
4.2
1.3
STD.
DEV.
1.1
0.1
2.1
1.2
3.6
0.5
4.1
1.4
3.2
2.4
0.9
3.4
2.3
1.0
.0.0
1.6
1.3
2.3
0;6
3.0
0.4,
6.4
1.4
,0.3
. 1.0
0.3
0.7
0.3
". :3.3
0.8
1.3
4.1
4.3
1.4
1.3
0.5
0.0
6.4
2.8
1.0
2.2
5.5
2.9
MAXIMUM
4.1
0.6
-, 3.3
3.8
12.5
1.5
29.9
7.8
17.0
11.2
1,8
12.3
8.8
2.9
0.4
4.5
4.2
5.1
2.0
8.0
0.6
19.6
3.4
1.3
3.0
0.8
i:s
1.0
5.1
2.7
3.8
12.0
14.2
5.2
3.8
2.4
2.7
13.4
12.4
4.1
7.2
21.3
11.6
%>4 pCi/L
4
, 0
0
0
33
0
30
5
16
19
0
8
38
0
0
17
20
.50
0
29
0
50
0
0
0
0
, 0
0
50
0
0
18
. 38
33
0
0
0
50
11
7
11
52
13
%>20 pCi/L
0
0
0
0
0
0
1
0
0
. 0
0
0
0
' 0
o_
0
0
0
0
0
0
0
0
0
0
0
0
0
0
', 0
0
0
0
0
0
o
0
0
0
0
0
4
0
-------
TABLE 1 (continued). Screening indoor radon data for Missouri.
COUNTY
PULASKI
PUTNAM
RALLS
RANDOLPH
RAY
REYNOLDS
RIPLEY
SALINE
SCHUYLER
SCOTLAND
SCOTT
SHANNON
SHFJ,BY
ST. CHARLES
ST.CLAIR
ST. FRANCOIS
ST. LOUIS
ST. LOUIS CITY
STE. GENEVIEVE
STODDARD
STONE
SULLIVAN
TANEY
TEXAS
VERNON
WARREN
WASHINGTON
WAYNE
WEBSTER
WORTH
WRIGHT
NO. OF
MEAS.
12
3
1
6
17
1
11
9
1
4
13
6
3
50
3
48
91
207
11
9
9
2
10
8
13
6
4
8
15
2
7
MEAN
0.7
0.7
0.9
1.3
2.7
2.7
3.1
4.7
2.3
1.1
1.3
5.0
3.2
2.5
2.9
2.5
2.3
2.3
1.4
1.3
2.3
1.4
1.8
5.0
1.1
1.3
0.9
2.5
1.8
1.0
1.1
GEOM.
MEAN
0.6
0.6
0.9
1.1
1.8
2.7
1.9
3.4
2.3
0.7
0.9
2.6
2.3
1.7
2.5
1.6
1.7
1.6
0.8
0.9
1.5
1.3
1.5
0.9
0.9
1.1
0.8
1.4
1.0
0.9
0.9'
MEDIAN
0.6
0.7
0.9
1.3
1.6
' 2.7
1.4
3.8
2.3
1.0
1.0
2.2
1.4
1.7
3.3
1.6
1.6
1.6
1.2
0.9
2.4
1.4
1.4
0.6
0.7
1.0
0.7
1.2
0.9
1.0
0.8
STD.
DEV.
0.5
0.3
0.0
0.6
3.1
0.0
3.0
3.8
0.0
0.9
1.0
7.5
3.1
2.8
1.6
2.8
2.6
3.1
1.4
1.0
2.1
0.2
1.1
11.8
0.8
0.8
0.6
2.8
2.3
0.1
0.8
MAXIMUM
2.2
0.9
0.9
2.1
10.8
2.7
8.3
12.5
2.3
2.2
3.4
20.3
6.8
13.9
4.2
15.8
17.8
37.5
5.2
3.1
7.0
1.5
3.7
34.0
2.9
2.6
1.7
8.2
8.0
1.0
2.7
%>4 pCi/L
0
0
0
0
12
0
27
44
0
0
0
17
33
16
33
17
13
13
9
0
11
0
0
- . 13
0
0
0
25
13
0
0
%>20 pCi/L
0
0
0
0
0
0
0
0
0
0
0
17
0
0
0
0
0
0
0
0
0
0
0
13
0
0
0
0
0
0
0
-------
Some persistent patterns are present in the survey data. Elevated (> 4 pCi/L) screening "
indoor radon levels occur along the upper Missouri River drainage in an area extending from
Atchison County to Lafayette. County. This area is underlain by river alluvium, loess, and
residuuiri developed on limestone and shale. The loess deposits along the river north of Kansas
City are somewhat elevated in uranium and some residual soils developed on limestone and shale
in southern Jackson County are somewhat excessively drained.
A broad area of counties with elevated indoor radon levels occurs in the southern, eastern,
and western part of the Ozark Plateau Province. This is an area of locally moderately elevated elJ
values, somewhat excessively drained soils, and karst. /
Elevated eU values are associated with granite and rhyolite exposed in Washington, Iron,
St Francois, and Madison Counties, yet only Madison and St Francois Counties have elevated
averge indoor radon levels (fig. 11). Sampled houses in Washington and Iron Counties simply
may not be located on soils developed on the granite and rhyolite. Elevated eU values are
associated with basal Cretaceous sedimentary rocks of the Mississippi Embaymerit underlying
northern Scott and Stoddard Counties and southeastern Butler County, yet elevated indoor radon
levels are not present in Scott and Stoddard Counties. Again, sampling demographics may play a
role. However, this part of the State is also characterized by high rainfall and elevated soil
moisture, so radon migration may be inhibited.
GEOLOGIC RADON POTENTIAL :'..
Elevated indoor radon levels can be expected in several geologic settings in Missouri.
Uranium-bearing granites and rhyolites and residuum developed on carbonate rocks in the Ozark '
Plateau Province are likely to have significant percentages of homes with indoor radon levels
exceeding 4 pCi/L. The most likely areas are those in which elevated eU values occur (fig. 8).
Where structures are sited on somewhat excessively drained soils in this area (fig. 9) the radon
potential is further increased. Extreme indoor radon levels may occur where structures are sited on
uranium occurrences and where the disturbed zone around a foundation is connected to solution
openings in carbonate rocks or to open zones in soil and bedrock caused by mine subsidence.
Karst underlies parts of the City and County of St. Louis and may locally cause elevated indoor
radon levels. Elevated eU and significant karst development occur in Perry and Cape Girardeau
Counties. Structures sited on locally highly permeable karst soils with elevated eU in these two
counties will likely have elevated indoor radon levels.
Elevated indoor radon levels may occur where the foundations of structures intercept the
thin Pennsylvanian black shales or the Chattanooga Shale in the southwestern part of the State
from Kansas City south to McDonald and Barry Counties and in north-central Missouri in Boone,
Randolph and Macon Counties, or where they intercept well-drained alluvium derived from these
rocks. Because these uranium-bearing shales are so thin, such circumstances are likely to be very
site- or tract-specific, so detailed geologic and soil mapping will be necessary to outline areas of
potential problems. Where these shales are jointed or fractured or soils formed on them are
somewhat excessively drained on hillslopes, the radon potential is further increased. Indoor radon
levels exceeding 100 pCi/L have been reported for homes sited on the Ohio Shale (Upper
Devonian) in the Columbus, Ohio metropolitan area (Michael Hansen, oral commun., 1987).
Residuum developed on limestones associated with these uranium-bearing shales may also have
elevated uranium levels and have significant geologic radon potential.
IV-21 Reprinted from USGS Open-File Report 93-292-G
-------
Alluvium and loess along the upper Missouri River Valley upstream from Kansas City
seem to be producing elevated indoor radon levels that may be related to the somewhat elevated
uranium content of these materials and, possibly, to increased radon emanation and diffusive
transport associated with well-drained loess deposits. Detailed studies of indoor radon data in this
area would be necessary to determine more closely the origin of elevated indoor radon levels.
Thin, somewhat excessively drained soils developed on limestone that occur as part of one soil
association in the southern suburbs of Kansas City may also be related to elevated indoor radon
levels in Jackson County. Information on the equivalent uranium content of these soils is not
available as aeroradiometric data were not gathered over this area.
A multi-county area in northeastern Missouri would seem to have relatively low radon
potential, which is probably related to very poorly drained soils developed on loess and glacial
deposits. However, a single 6.8 pCi/L basement radon measurement in Shelby County remains
unexplained, so some caution should be exercised in evaluating this area.
The geologic radon potential also seems low in the southeastern lowland area. Only one
indoor radon value exceeding 4 pCi/L is reported for a six-county area, and very poorly drained
soils are widespread (fig. 10). However, some aeroradiometric anomalies occur in this area
(fig. 8), and some excessively drained soils occur locally (fig. 9). Elevated indoor radon levels
may be associated with these locales. Some site-specific sampling is needed in these areas.
SUMMARY
There are seven areas in Missouri for which geologic radon potential may be evaluated (fig.
12). A relative index of radon potential (RI) and an index of the level of confidence in the available
data (CI) have been established (see discussion in the introductory section of this volume). These
areas are evaluated in Table 2.
The northwestern part of Missouri has high overall radon potential. This area includes
alluvium with elevated uranium contents along the upper Missouri River Valley, adajacent areas of
thick loess just east of the valley, and areas underlain ,by Pennsylvanian black shales near Kansas
City.
The dissected till plain of northern Missouri has moderate overall radon potential, but this
assessment has moderate confidence. Except for counties along the Missouri River, the indoor
radon data for the counties in the dissected till plain are sparse and appear to be biased on the low
side. The eastern half of this area has soils of low permeability, but moderate uranium contents.
The unglaciated part of the Osage Plain province has a moderate overall radon potential;
however, areas of very slowly permeable soils have lower radon potential, and areas of thin soils
underlain by the uranium-bearing shales in this province have high radon potential, with locally
extreme values possible.
The Ozark Plateau Province has a moderate overall geologic radon potential. Several areas
of somewhat excessively drained soils, scattered uranium occurrences, carbonate soils in which
uranium has been concentrated, and areas of karst all contribute to the moderate radon potential of
this area. The indoor radon data support this conclusion but far more data need to be gathered to
increase the confidence level.
The carbonate region has moderate geologic radon potential. Intense karst development,
elevated uranium in residual soils developed on carbonate, and large areas of somewhat
excessively drained to excessively drained soils contribute to this evaluation.
IV-22 Reprinted from USGS Open-File Report 93-292-G
-------
The St Francois Mountains have high geologic radon potential owing to elevated levels of
uranium in soils developed on granitic and vtilcanic rocks throughout these mountains arid tov
substantial areas of somewhat excessively to excessively drained soils.
The Coastal Plain Province has a low geologic radon potential overall. Although elevated
ell occurs over some of the sedimentary rocks in this province, the high soil moisture, very poorly
drained soils, and the low indoor radon values all point towards low radon potential. Elevated eU
over similar rocks in the coastal plain of Alabama did not produce elevated indoor radon levels
there.
This is a generalized assessment of the State's geologic radon potential and there is no
substitute for having a home tested. The conclusions about radon potential presented in this report
cannot be applied to individual homes or building sites. Indoor radon levels, both high and low,
can be quite localized, and within any radon potential area there will likely be areas with higher or
lower radon potential that assigned to the area as a whole. Any local decisions about radon should
not be made without consulting all available local data. For additional information on radon and
how to test, contact your State radon program or EPA regional office. More detailed information
on state or local geology may be obtained from the State geological survey. Addresses and phone
numbers for these agencies are listed in chapter 1 of this booklet. ,
IV-23 Reprinted from USGS Open-File Report 93-292-G
-------
TABLE 2. Radon Index (RI) and Confidence Index (CI) for geologic radon potential areas of
Missouri. See figure 12 for locations of areas. See the introductory chapter for discussion of RI
andCL
Dissected
till
plain
FACTOR RI CI
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERMEABILITY
ARCHITECTURE
GFE POINTS
TOTAL
2
2
2
2
3
0
11
RANKING Mod
2
2
2
3
9
Mod
Unglaciated
Osage
plain
RI CI
2
'2 -
2
2
3
0
11
Mod
3
3
3
3
12
High
Ozark
Plateau
RI CI
1
1
3
3
3
0
11
Mod
3
3
3
3
12
High
Coastal
Plain
RI CI
1
2
1
2
1
-2
5
Low
2
3
2
3
10
Hi*
FACTOR
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERMEABILITY
ARCHITECTURE
GFE POINTS
TOTAL
RANKING
Carbonate
region
RI CI
2
2
2
2
3
0
11
Mod
3
3
3
3
12
High
St. Francois
Mountains
RI CI
2
3
3
2
3
0
13
High
3
3
3
3
12
High
Northwestern
Missouri
RI CI
3
2
3
2
3
0
13
High
3
3
3 ,
3
12
High
RADON INDEX SCORING:
Radon potential category
Point range
Probable screening indoor
radon average for area
LOW , 3-8 points <2pCi/L
MODERATE/VARIABLE 9-11 points 2-4pCi/L
HIGH > 11 points >4pCi/L
Possible range of points = 3 to 17
CONFIDENCE INDEX SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
4-6 points
7-9 points
10 -12 points
Possible range of points = 4 to 12
IV-24 Reprinted from USGS Open-File Report 93-292-G
-------
-I
L'.
r
''.-^x--^"--^--T^--\\ ;>
idJ^V:-.-^-!.: -.0- --
'' V^'V^T--^-^
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Fig. 12- Radon potential areas in Missouri. DTP- Dissected till plain; NW- Northwest Missouri;
UOP- Unglaciated Osage Plain; OP- Ozark Plateau; CR- Carbonate region; SFM- SL Francois
Mountains; CP- Coastal Plain. Radon potential: Cross-hatched- low; stippled- moderate; blank-
high. .
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REFERENCES CITED IN THIS REPORT
AND GENERAL REFERENCES PERTAINING TO RADON IN MISSOURI
Coveney, R. M., Jr., 1981, Thin black Pennsylvanian-age shales .of the Mid-continent U.S.; a
neglected metallic resource?: Geological Society of America Abstracts with Programs,
v.13, n.7, p. 432. .
* * , . -
Coveney, Raymond M., Jr., Hilpman, Paul L., Allen, Ashley V., and Glascock, Michael D.,
1987, Radionuclides in Pennsylvanian black shales of the midwestern United States, in
Marikos, Mark Alan and Hansman, Robert H., eds., Geologic causes of natural
radionuclide anomalies, Proceedings of the GEORAD conference, St. Louis, MO, April
21-22,1987: Missouri Department of Natural Resources SpecialPublication 4, p. 25-42.
Coveney, Raymond M., Jr., Leventhal, Joel S., and Glascock, Michael D., 1987, Origins of
metals and organic matter in the Mecca Quarry Shale Member and stratigraphicaUy
equivalent beds across the Midwest: Economic Geology, v.82, no. 4, p. 915-933.
Duley, J.W., 1983, Geologic aspects of individual home liquid-waste disposal in Missouri:
Missouri Division of Geology and Land Survey Engineering Geology Report No. 7, 78 p.
Duval, Joseph S. and Jones, William J., 1988, Regional aerial gamma-ray maps for Illinois and
parts of Wisconsin, Iowa, Michigan, Indiana, Missouri, and Kentucky, in Marikos, Mark
Alan and Hansman, Robert H., eds., Geologic causes of natural radionuclide anomalies,
Proceedings of the GEORAD conference, St. Louis, MO, Apr. 21-22,1987: Missouri
Department of Natural Resources Special Publication 4, p. 157-166:
Duval, J. S., Jones, W. J., Riggle, F. R., and Pitkin, J. A., 1989, Equivalent uranium map of the
conterminous United States: U.S. Geological Survey Open-File Report 89-478,10 p.
Erickson, R. L. and Pratt, W. P., 1981, Coastal plain-type uranium deposits, in Pratt, W. P., ed.,
Metallic mineral-resource potential of the Rolla 1° x 2° quadrangle, Missouri, as appraised
in September 1980: U.S. Geological Survey Open-File Report 81-518, 50 p.
Greeman, D.J., Rose, A.W., and Jester, W.A., 1990, Form and behavior of radium, uranium,
and thorium in central Pennsylvania soils derived from dolomite: Geophysical Research
Letters, v. 17, no.6, p. 833-836.
Howe, W.B.,1984, Generalized geologic map of Missouri: Rolla, MO, Geology and Land
Survey, Department of Natural Resources. 1 p. "
Johnson, V. G. and Dubyk, W. S., 1977, Preliminary study of the geology and uranium
favorability of the Forest City Basin in Kansas, Missouri, Iowa, and Nebraska: U.S.
Department of Energy Report No. GJBX-83(77), 18 p.
IV-26 Reprinted from USGS Open-File Report 93-292-G
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Kisvarsanyi, E. B., 1981, Uranium and thorium in Precambrian rocks, in Pratt, W. P., ed.,
Metallic mineral-resource potential of the Rolla 1° x 2° quadrangle, Missouri, as appraised
in September 1980: United States Geological Survey Open-File Report 81-518,50 p.
Kisvarsanyi, E. B., 1987, Radioactive HHP (high heat production) granites in the Precambrian
terrane of southeastern Missouri, in Marikos, Mark Alan and Hansman, Robert H., eds.,
Geologic causes of natural radionuclide anomaUes, Proceedings of the GEORAD
conference^ St. Louis, MO, Apr. 21-22,1987: Missouri Department of Natural Resources
Special Publication 4, p. 5-16.
Marikos, M. A., 1981, Distribution and possible causes of radionuclides in groundwaters of
Missouri, in Hemphill, D. D., ed., Proceedings of University of Missouri's 15th annual
conference on trace substances in environmental health, Columbia, MO, June 1-4,1981:
Trace Substances in Environmental Health, v. 15,86 p.
Missouri Geological Survey, 1983, Surficial materials map of Missouri: Rolla, MO, Missorui
Geological Survey, Missouri Department of Natural Resources, 1 p.
Muilenburg, .G.A., Notes on uranium, revised edition: Missouri Division of Geological Survey
and Water Resources Information Circular No. 5, 22 p. ^
Nuelle, Laurence M., 1987, Distribution of radionuclides in Missouri geologic terranes: a
summary of available data and the need for more data, in Marikos, Mark Alan and
Hansman, Robert EL, eds., Geologic causes of natural radionuclide anomalies,
Proceedings of the GEORAD conference, St. Louis, MO, Apr. 21-22, 1987: Missouri
Department of Natural Resources Special Publication 4, p. 75-90.
Odland, S. K.; Millard, H. T., Jr., 1979, Uranium and thorium content of some sedimentary and
igneous rocks from the Rolla 1° x 2° quadrangle, Missouri: U. S. Geological Survey Open-
File Report 79-1080, 17 p. ; ,
Pratt, W. P., 1981, Uranium in Paleozoic sedimentary rocks, m Pratt, W. P., ed., Metallic
mineral-resource potential of the Rolla 1° x 2° quadrangle, Missouri, as appraised in
September 1980: United States Geological Survey Open-File Report 81-0518, 50 p.
Proctor, P. D. and O'Brien, W. P., 1980, Radiometric signature and petrochemistry of the
Graniteville,Granite, St. Francois Mountains, Southeast Missouri: Geological Society of
America Abstract with Programs, v.l2, n.5, p. 254.
Proctor, P. D., O'Brien, W. and Grant, S. K., 1981, Graniteville Granite, Missouri; a possible
Bokan Mountain, Alaska, analog?: Geological Society of America Abstracts with
Programs, v.13, no.7, p. 533.
IV-27 Reprinted from USGS Open-File Report 93-292-G
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Rose, A.W., Ciolkosz, EJ., and Washington, J.W., 1990, Effects of regional and seasonal
variations in soil moisture and temperature on soil gas radon, in U.S. Environmental
Protection Agency, The 1990 international symposium on radon and radon reduction
technology: Volume in. Preprints, unpaginated.
\
Sauer, Herbert I. and Mirielli, Edward J., Jr., 1987, Associations of natural radiation and radon
with the risk of dying, in Hemphill, D. D., ed., Proceedings of University of Missouri's
15th annual conference on trace substances in environmental health, Columbia, MO, June
1-4,1981: Trace Substances in Environmental Health, v. 15, p. 195-202.
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.
Sims, Paul K., Schulz, Klaus J. and Kisvarsanyi, Eva B., 1990, Proterozoic anorogenic granite-
rhyolite terranes in the Midcontinental United States; possible hosts for Cu-, Au-, Ag-, U-,
and rare-earth element-bearing iron oxide deposits similar to the Olympic Dam orebody, in
Pratt, Walden P. and Goldhaber, Martin B., eds., U.S. Geological Survey-Missouri
Geological Survey symposium; Mineral-resource potential of the Midcontinent; program
and abstracts, St. Louis, Missouri, April 11-12, 1989: U.S. Geological Survey Circular
1043, p. 33-34.
Steele, K. F. and Fay, W. M., 1982, Orientation study of St. Francois Mountain and Decaturville
Precambrian areas, Missouri; hydrogeochemical and stream sediment reconnaissance: U.S.
Dept of Energy Report No. GJBX-200(82), 72 p.
Steele, S. R., Hood, W. C. and Sexton, J. L., 1982, Radon emanation in the New Madrid seismic
zone, in McKeown, F. A. and PaMser, L. C., eds., Investigations of the New Madrid,
Missouri, earthquake region: U. S. Geological Survey Professional Paper 1236,
p. 191-201.
Szabo, B. J., 1979, Extreme fractionation of U/ U isotopes within a Missouri aquifer: U.S.
Geological Survey Professional Paper 1150,188 p.
Szabo, B. J., 1980, Extreme 234U/238U and 230Th/234U activity ratios in Missouri groundwaters
and spring deposits; dating organic sand samples and fossil bones by the uranium-series
method: Geological Society of America Abstracts with Programs, v. 12, no.7, p. 532.
Szabo, B. J., 1982, Extreme fractionation of 234U/238U and 230Th/234U in spring waters,
sediments, and fossils at the Pomme de Terre Valley, southwestern Missouri: Geochimica
et Cosmochimica Acta, v. 46, no. 9, p. 1675-1679.
IV-28 Reprinted from USGS Open-File Report 93-292-G
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Unfer, L., Jr. and Tibbs, N. H., 1980, Radioactivity in the Cretaceous and Tertiary sediments of
Crowleys Ridge, Southeast Missouri: Geological Society of America Abstract with
Programs, v. 12, no. 5, p. 258-259. '
U.S. Geological Survey, 1974, The National Adas of the United States of America.
IV-29 Reprinted from USGS Open-File Report 93-292-G
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EPA's Map of Radon Zones
The USGS'Geologic Radon Province Map is the technical foundation for EPA's Map
of Radon Zones. The Geologic Radon Province Map defines the radon potential for
approximately 360 geologic provinces. EPA has adapted this information to fit a county
boundary map in order to produce the Map of Radon Zones. \
The Map 'of Radon Zones is based on the same range of predicted screening levels of
indoor radon as USGS1 Geologic Radon Province Map. EPA defines the three zones as
follows: Zone One areas have an average predicted indoor radon screening potential greater
than 4 pCi/L. Zone Two areas are predicted tp have an average indoor radon screening
potential between 2 pCi/L and 4 pCi/L. Zone Three areas are predicted to have an average
indoor radon screening potential less than 2 pCi/L. , '
Since the geologic province boundaries cross state and county boundaries, a strict
translation of counties from the Geologic Radon Province Map to the Map of Radon Zones
was not possible For counties that have variable radon potential (i.e., are located in two or
more provinces of,different rankings),, the counties were'assigned to a zone based on the
predicted radon potential of the province in which most of its area lies. (See Part I for more
details.) ''; '
MISSOURI MAP OF RADON ZONES . ,
. The Missouri Map of Radon,Zones and its supporting documentation (Part TV of this .
report) have received extensive review by Missouri geologists and radon program experts.
The map for Missouri generally reflects current State knowledge about radon for its counties.
Some States have been able to conduct radon investigations in areas smaller than geologic
provinces and counties, so it is important'to consult locally available data.
Although the information provided in Part TV of this report --/the State chapter entitled
"Preliminary Geologic Radon Potential Assessment of Missouri" may appear to be quite .
specific, it cannot be applied to determine the radon levels,of a neighborhood, housing tract,
individual house, etc. THE ONLY WAY TO DETERMINE IF A HOUSE HAS
ELEVATED INDOOR RADON IS TO TEST, Contact the Region 7 EPA office or the
.Missouri radon program for information on testing and fixing homes. Telephone numbers and
addresses can be found in Part II of this report. ,
V-l
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